Brain & Development xxx (2014) xxx–xxx www.elsevier.com/locate/braindev
Original article
Giant axonal disease: Report of eight cases Faruk Incecik a,⇑, Ozlem M. Herguner a, Serdar Ceylaner b, Suzan Zorludemir c, Sakir Altunbasak a a
Division of Pediatric Neurology, Department of Pediatrics, Cukurova University Faculty of Medicine, Adana, Turkey b Intergen Genetics Centre, Ankara, Turkey c Department of Pathology, Cukurova University Faculty of Medicine, Adana, Turkey Received 7 May 2014; received in revised form 2 December 2014; accepted 3 December 2014
Abstract Background: Giant axonal neuropathy (GAN) is an autosomal recessive inherited progressive motor and sensory neuropathy with typical onset in early childhood. The disease is caused by GAN gene mutations on chromosome 16q24.1. To determine clinical and genetic results in Turkish patients with GAN. Methods: Eight children with GAN were retrospectively analyzed. Five (62.5%) were girls and 3 (37.5%) were boys with the mean age on admission 10.13 ± 3.8 years (range: 5–15 years). Results: Parental consanguinity was found in all the families. The patients had the classical clinical phenotype characterized by a severe axonal neuropathy with kinky hair. Two patients had contractures of extremities, and not walking. One patient was walking with aid. The other patients were walking without aid. Mutation analysis was performed in two patients and IVS9 (+1G > T) (homozygous) mutation was detected. Conclusion: The classical clinical findings allowed considering the GAN diagnosis, but, in atypical cases and milder phenotypes, the presence of giant axons in nerve biopsy was helpful to specify molecular analysis. Ó 2014 Published by Elsevier B.V. on behalf of The Japanese Society of Child Neurology.
Keywords: Giant axonal neuropathy; GAN mutations; Children
1. Introduction Giant axonal neuropathy (GAN) is a severe autosomal recessive childhood disorder affecting both the peripheral nervous system (PNS) and the central nervous system (CNS). The majority of cases of GAN have age of onset of approximately 3 years with developmental delay, patients have similar appearance, usually kinky hair, an axonal neuropathy and CNS abnormalities [1]. Life expectation is between age of 10 and 30 years [2]. ⇑ Corresponding author at: Toros mah., Barısß Manc¸o Bul. 78178 Sok., Yesßilpark evleri, A blok, kat:7/13, C ¸ ukurova, Adana, Turkey. E-mail address: fi[email protected] (F. Incecik).
The hallmark of the disease on peripheral nerve biopsy is a giant axonal swelling due to massive accumulation of neurofilaments. Thus a generalized disorganization of intermediate filaments is indicated [3]. A major chromosomal locus for GAN maps to chromosome 16q24.1 and several disease causing mutations were identified in the gigaxonin (GAN) gene which is a member of the BTB/kelch protein superfamily [4]. These mutations result in loss of function of gigaxonin, an ubiquitously expressed protein. Gigaxonin stabilizes the microtubule network thus playing an important role in the cytoskeleton. Here we report the clinical manifestations and results of genetic study in eight Turkish patients with GAN.
http://dx.doi.org/10.1016/j.braindev.2014.12.002 0387-7604/Ó 2014 Published by Elsevier B.V. on behalf of The Japanese Society of Child Neurology.
Please cite this article in press as: Incecik F et al. Giant axonal disease: Report of eight cases. Brain Dev (2014), http://dx.doi.org/10.1016/ j.braindev.2014.12.002
2
F. Incecik et al. / Brain & Development xxx (2014) xxx–xxx
2. Material and methods We detected eight children diagnosed with GAN. GAN diagnosis was made both clinical and pathological findings. The data were retrospectively collected from the clinic files and included age, sex, consanguinity, family history of GAN, initial and clinical symptoms, investigation results on electroencephalogram (EEG), cerebral magnetic resonance imaging (MRI), nerve conduction studies, the nerve biopsy, and mutation analysis. Cerebral MRI were performed in all of patients. Nerve conduction studies were performed with surface stimulation and recording electrodes. Motor nerve conduction velocity studies (MNCVs) in the median and the peroneal nerves were recorded. Antidromic sensory action potential was recorded from the median nerve. Electromyography of the tibialis anterior and the first dorsalis interosseous muscle was performed with a concentric needle electrode. Electroencephalograms were performed in four patients. The nerve biopsy was performed in all of them. The nerve biopsy specimen was divided into two portions. One was fixed in 10% formalin and paraffin-embedded for standard examination. The other one was immediately fixed in Karnovsky’s fixative (containing 2.5% glutaraldehyde and 2% paraformaldehyde) and postfixed in 1% osmium tetroxide. Eponembedded one-micron thick sections stained with toluidin blue were prepared for light microscope examination. Mutation analysis could studied in two patients. The other parents did not accept genetic studies. 3. Results Among the 8 patients, 5 (62.5%) were girls and 3 (37.5%) were boys and the mean age on admission was 10. 13 ± 3.8 years (range: 5–15 years). Parental consanguinity was found in all the families. Patient 5 and 6 were siblings. The most severely affected sibling (patient 5) had generalized hypotonia, contractures of extremities, scoliosis, ptosis, nystagmus, feeding problems and excessive salivations. He could not walking. Second sibling had nystagmus, ataxic gait, dysmetria and dysdiadochokinesia. Two patients had contractures of extremities, and not walking (patient 1, 5). One patient was walking with aid (patient 8). The other patients were walking without aid. The all patients had kinky hair since early childhood (Fig. 1). Current patients had similar clinical presentation, compatible with a degenerative disease. Their clinical features showed in Table 1. All of them were born after an uneventful pregnancy and delivery. Onset of disease varied from 2 to 5 years of age. The initial complaint in all them were clumsy gait, falls, and weakness. Cerebellar abnormalities became apparent within a few years. Five patients had prominent cerebellar symptoms such as ataxia, nystagmus, and dysmetria.
Fig. 1. Typical kinky hair of patient 3.
MRI of the brain showed generalized both cerebral and cerebellar atrophy in two patients (patient 1, 5) and only cerebellar atrophy in two patients (patient 2, 8). White matter lesions were not found in all them. Electroencephalograms were performed in four patients, and they were normal. Nerve conduction studies showed predominantly axonal sensory-motor neuropathy in all patients. In the nerve biopsies, moderate myelinated nerve fibers loss, several regenerative clusters and multiple giant axons about 10–30 per funicle were shown in all of them. Giant axons were measured 25–40 micron in diameter. Focal demyelination, hypertrophic “onion bulb” changes and endoneurial fibrosis were also seen in the microscopic examination. Immunohistochemically neurofilament protein accumulation was detectable in giant axons (Fig. 2A and B). Mutation analysis was performed in two patients and IVS9 (+1G > T) (homozygous) mutation was detected. The findings of patients are summarized in Table 1. 4. Discussion Among the peripheral neuropathies in childhood, GAN shows some unique clinical and morphological features. Age at onset may be from soon after birth to up to 10 years of age, or older. The peripheral neuropathy presents with evidence of both motor and sensory involvement, with progressive weakness and hyporeflexia in the first seven years of life. Most patients become wheelchair dependent in the second decade of life and die in the third decade. They eventually become bedridden with severe polyneuropathy, ataxia, and dementia. Deaths results from secondary complications, such as respiratory failure. Early observations depicted clinical features of peripheral neuropathy in children with ‘remarkably kinky hair’. Affected children may develop symptoms that progress from clumsy gait to a pronounced difficulty to ambulate. Symptoms vary
Please cite this article in press as: Incecik F et al. Giant axonal disease: Report of eight cases. Brain Dev (2014), http://dx.doi.org/10.1016/ j.braindev.2014.12.002
F. Incecik et al. / Brain & Development xxx (2014) xxx–xxx
3
Table 1 Clinical and molecular data of the patients. Data
Patient 1
Patient 2
Patient 3
Patient 4
Patient 5
Patient 6
Patient 7
Patient 8
Age/sex Age at onset Initial symptoms
14/F 3 Weakness
15/M 4 Weakness
Yes No No
Yes Yes Yes (10 years)
11/F 5 Clumsy gait Yes No No
13/F 3.5 Clumsy gait Yes No No
8/F 2 Falls
Yes Yes Yes (9 years)
8/F 4 Clumsy gait Yes No No
5/M 3 Falls
Kinky hair Facial weakness Mental deterioration Scoliosis Ptosis Areflexia Cerebellar signs Babinski’s sign Peripheral neuropathy EEG abnormality Extremity deformities Motor capacity
12/M 5 Clumsy gait Yes No No
Yes No Yes (6 years)
Yes Yes Yes Yes Yes Yes
Yes No Yes Yes No Yes
No No Yes No No Yes
No No Yes No No Yes
Yes Yes Yes Yes Yes Yes
No No Yes Yes No Yes
No No Yes No No Yes
Yes Yes Yes Yes No Yes
No Yes
NP No
No No
NP No
No Yes
NP No
NP No
No No
WCB (12 years) Yes NP
Walking
Walking
Walking
Walking
Walking
Yes NP
Yes Yes
Yes Yes
WCB (12 years) Yes NP
Yes NP
Yes NP
Walking with aid Yes NP
Nerve biopsy GAN mutations
NP: not performed. WCB: wheelchair bound. Yes: performed.
Fig. 2. (A and B) Giant axons with aberrant neurofilament immunostaining on sural nerve biopsy of patient 5.
considerably. The typical clinical manifestations of GAN present with evidence of both motor and sensory involvement, including progressive and predominant distal clumsiness and muscle weakness, impaired sensation, absent tendon reflexes, and pronounced gait disturbance [1,5]. The diagnosis of GAN is suggested in individuals with following: (1) Severe early-onset peripheral motor and sensory neuropathy, (2) Tightly curled lackluster hair that differs markedly from that of the parents, (3) CNS involvement including intellectual disability, cerebellar signs, and pyramidal tract signs [5]. The cranial nerves can also be affected, especially the third and the seventh. Lesions in the brain, cerebellum
and spinal cord can cause mental retardation, dysmetria, seizures, nystagmus, and dysarthria, as well as signs of spasticity. Scoliosis, kyphosis, optic atrophy, ophthalmoplegia, and epilepsy are reported less commonly [1,6,7]. Involvement of the cerebral cortex, cerebellum, brainstem, anterior horn cells, and pyramidal tracts was also shown in postmortem studies of patients with GAN [4,8]. In the majority of reported GAN cases, CNS involvement is described early in the course of the disease. But, we detected diffuse cerebral and cerebellar atrophy in MRI only in four patients. There were no lesions of white matter disease. Unlikely sometimes, the symptoms and signs of CNS involvement can predominate. It is reported that even if there is no clinical
Please cite this article in press as: Incecik F et al. Giant axonal disease: Report of eight cases. Brain Dev (2014), http://dx.doi.org/10.1016/ j.braindev.2014.12.002
4
F. Incecik et al. / Brain & Development xxx (2014) xxx–xxx
sign of CNS involvement, there may be EEG and MRI abnormalities [6]. Some rare diseases may have to be considered in the differential diagnosis, such as severe early-onset hereditary neuropathies (CMT4A, CMT4B, CMT4C, CMT4E) and infantile neuroaxonal dystrophy, which has more evidence of cerebral involvement and more scattered lesions in the peripheral nerves differing, especially on ultramicroscopic examination, in their pathological appearance. In some CMT cases, typical giant axons may occur. Yet giant axonal neuropathy is a disorder affecting other intermediate filaments. In addition to axons, Schwann cells, cardiac muscle fibers, and hairs are characteristically involved. Other types of neuropathy have to be excluded, such as toxic neuropathies due to glue sniffing for example, vitamin B12 deficiency, diabetes mellitus and amyloid polyneuropathies [5,9]. When the CNS is affected, other types of spinocerebellar degeneration may cause difficulties, as well as Alexander disease, Fazio–Londe disease with cranial nerve involvement, and Menkes’ syndrome [2]. Menkes disease is a rare X-linked recessive disorder with prominent CNS involvement and hair changes resembling those of GAN. Patients with classic Menkes disease appear healthy until age two to three months, when loss of developmental milestones, hypotonia, seizures, and failure to thrive occur. The diagnosis is usually suspected when infants exhibit typical neurological changes and concomitant changes of hair [10]. The color of the hair is most often reported as white, silver or gray, a result of marked reduction of melanin and an associated abundance of tyrosinase. Clinically the hair appears short, sparse, coarse, lusterless and twisted. Hair shaft abnormalities include pilitorti and monilethrix, sometimes trichorrhexis and trichoptilosis. These structural changes are due to a defect in the copper-enzyme dependent cross-linkage of disulfide bands in the hair’s keratin. Kinky or curly hairs are characteristic clinical abnormality in patients with GAN. It usually appears in early years. But in the literature, they showed that presence of kinky or curly hairs was not a constant finding as patients with normal hair were described [11]. In typically GAN, children have curly hair and characteristic pilor alterations with pseudopili torti aspect occurring early in life before neuropathy is clinically present. All of our patients had the typical GAN phenotype with kinky hair. CNS involvement can cause epileptic seizures and mental deterioration. Mental deterioration was noted to start before the age of 10 years [2,12]. Our patients had normal mental status except for three. In EEG, disorganized background activity with focal spikes, spike-slow wave discharges, and paroxysmal slow wave activity were reported in literature [12,13]. None of our patients had seizures, we found not any EEG abnormalities in them. In GAN, histological findings in peripheral nerve biopsies, including those of autonomic nerves, include
enlarged axons with an accumulation of neurofilaments [2]. In fact, three types of filament are defective in this condition: neurofilaments, glial filaments, and intermediate filaments. The last are found in skin fibroblasts, Schwann cells, axons, and muscle fibers. The findings suggest that the disease may be caused by a generalized disorders of cytoplasmic microfilaments. Many onion bulb formations of Schwann cells are present [14]. In the CNS, as well as astrocytic degeneration, there is a loss of Purkinje cells and anterior horn cells. Brain demyelination has been reported, and Rosenthal fibers, so that Alexander’s disease may be suspected. Parts of the cerebrum most affected include the corticospinal tracts, the middle cerebellar peduncles, the posterior columns, and the olivocerebellar connections [15]. The gene for GAN was mapped to chromosome 16q24 [16]. Recently, the gene has been identified and found to encode for a novel, ubiquitously expressed protein named gigaxonin [17]. It has been suggested that the differences in the clinical presentation might be due to various mutations in the gene. Apart from these, in some families the disease has been reported not to be linked 16q24. In these patients, the disease has a slower progression with no signs of CNS involvement [18]. The previously reported Turkish patients, the 1502 + 1G > T and the R293X mutation were identified [4,11]. But, in our patients, IVS9 (+1G > T) (homozygous) mutation was found. We identified a novel homozygous mutation in the Turkish patients. Both of the patients had similar clinical findings, they had not pyramidal, cerebellar, and cranial nerve involvement yet. In conclusion, all GAN patients showed homogeneous clinical picture, mainly characterized by the involvement of neuroectodermal systems, including peripheral neuropathy, CNS features, and kinky hair. But, phenotypic heterogeneity of GAN is possible. In atypical cases and milder phenotypes, the presence of giant axons in nerve biopsy was helpful to specify molecular explorations. References [1] Igisu H, Ohta M, Tabira T, Hosokawa S, Goto I. Giant axonal neuropathy. A clinical entity affecting the central as well as the peripheral nervous system. Neurology 1975;25:717–21. [2] Ouvrier RA. Giant axonal neuropathy. A review. Brain Dev 1989;11:207–14. [3] Carpenter S, Karpati G, Andermann F, Gold R. Giant axonal neuropathy. A clinically and morphologically distinct neurological disease. Ann Neurol 1974;31:312–6. [4] Bomont P, Cavalier L, Blondeau F, Ben Hamida C, Belal S, Tazir M, et al. The gene encoding gigaxonin, a new member of the cytoskeletal BTB/kelch repeat family, is mutated in giant axonal neuropathy. Nat Genet 2000;26:370–4. [5] Tazir M, Nouioua S, Magy L, Huehne K, Assami S, Urtizberea A, et al. Phenotypic variability in giant axonal neuropathy. Neuromuscul Disord 2009;19:270–4. [6] Guazzi GC, Malandrini A, Gerli R, Federico A. Giant axonal neuropathy in 2 siblings: a generalized disorder of intermediate filaments. Eur Neurol 1991;31:50–6.
Please cite this article in press as: Incecik F et al. Giant axonal disease: Report of eight cases. Brain Dev (2014), http://dx.doi.org/10.1016/ j.braindev.2014.12.002
F. Incecik et al. / Brain & Development xxx (2014) xxx–xxx [7] Zhang LP, Zou LP. Clinical and genetic studies in a Chinese family with giant axonal neuropathy. J Child Neurol 2009;24:1552–6. [8] Kretzscmar HA, Berg BO, Davis RL. Giant axonal neuropathy: a neuropathological study. Acta Neuropathol 1987;73:138–44. [9] Zemmouri R, Azzedine H, Assami S, Kitouni N, Vallat JM, Maisonobe T, et al. Charcot–Marie–Tooth 2-like presentation of an Algerian family with giant axonal neuropathy. Neuromuscul Disord 2000;10:592–8. [10] Kodama H, Fujisawa C, Bhadhprasit W. Pathology, clinical features and treatments of congenital copper metabolic disordersfocus on neurologic aspects. Brain Dev 2011;33:243–51. [11] Sabatelli M, Bertini E, Servidei S, Fernandez E, Magi S, Tonali P. Giant axonal neuropathy: report on a case with focal fiber loss. Acta Neuropathol 1992;83:543–6. [12] Demir E, Bomont P, Erdem S, Cavalier L, Demirci M, Kose G, et al. Giant axonal neuropathy: clinical and genetic study in six cases. J Neurol Neurosurg Psychiatry 2005;76:825–32. [13] Lampl Y, Eshel Y, Ben-David E, Gilad R, Sarova-Pinhas I, Sandbank U. Giant axonal neuropathy with predominant central
[14] [15]
[16]
[17]
[18]
5
nervous system manifestations. Dev Med Child Neurol 1992;34:164–9. Gordon N. Giant axonal neuropathy. Dev Med Child Neurol 2004;46:717–9. Thomas C, Love S, Powell HC, Schultz P, Lampert PW. Giant axonal neuropathy: correlation of clinical findings with postmortem neuropathology. Ann Neurol 1987;22:79–84. Ben Hamida C, Cavalier L, Belal S, Sanhaji H, Nadal N, Barhoumi C, et al. Homozygosity mapping of giant axonal neuropathy gene to chromosome 16q24.1. Neurogenetics 1997;1:129–33. Kuhlenbaumer G, Young P, Oberwittler C, Hu¨nermund G, Schirmacher A, Domschke K, et al. Giant axonal neuropathy (GAN): case report and two novel mutations in the gigaxonin gene. Neurology 2002;58:1273–6. Tazir M, Vallat JM, Bomont P, Zemmouri R, Sindou P, Assami S, et al. Genetic heterogeneity in giant axonal neuropathy: an Algerian family not linked to chromosome 16q24.1. Neuromuscul Disord 2002;12:849–52.
Please cite this article in press as: Incecik F et al. Giant axonal disease: Report of eight cases. Brain Dev (2014), http://dx.doi.org/10.1016/ j.braindev.2014.12.002
Original article
Giant axonal disease: Report of eight cases Faruk Incecik a,⇑, Ozlem M. Herguner a, Serdar Ceylaner b, Suzan Zorludemir c, Sakir Altunbasak a a
Division of Pediatric Neurology, Department of Pediatrics, Cukurova University Faculty of Medicine, Adana, Turkey b Intergen Genetics Centre, Ankara, Turkey c Department of Pathology, Cukurova University Faculty of Medicine, Adana, Turkey Received 7 May 2014; received in revised form 2 December 2014; accepted 3 December 2014
Abstract Background: Giant axonal neuropathy (GAN) is an autosomal recessive inherited progressive motor and sensory neuropathy with typical onset in early childhood. The disease is caused by GAN gene mutations on chromosome 16q24.1. To determine clinical and genetic results in Turkish patients with GAN. Methods: Eight children with GAN were retrospectively analyzed. Five (62.5%) were girls and 3 (37.5%) were boys with the mean age on admission 10.13 ± 3.8 years (range: 5–15 years). Results: Parental consanguinity was found in all the families. The patients had the classical clinical phenotype characterized by a severe axonal neuropathy with kinky hair. Two patients had contractures of extremities, and not walking. One patient was walking with aid. The other patients were walking without aid. Mutation analysis was performed in two patients and IVS9 (+1G > T) (homozygous) mutation was detected. Conclusion: The classical clinical findings allowed considering the GAN diagnosis, but, in atypical cases and milder phenotypes, the presence of giant axons in nerve biopsy was helpful to specify molecular analysis. Ó 2014 Published by Elsevier B.V. on behalf of The Japanese Society of Child Neurology.
Keywords: Giant axonal neuropathy; GAN mutations; Children
1. Introduction Giant axonal neuropathy (GAN) is a severe autosomal recessive childhood disorder affecting both the peripheral nervous system (PNS) and the central nervous system (CNS). The majority of cases of GAN have age of onset of approximately 3 years with developmental delay, patients have similar appearance, usually kinky hair, an axonal neuropathy and CNS abnormalities [1]. Life expectation is between age of 10 and 30 years [2]. ⇑ Corresponding author at: Toros mah., Barısß Manc¸o Bul. 78178 Sok., Yesßilpark evleri, A blok, kat:7/13, C ¸ ukurova, Adana, Turkey. E-mail address: fi[email protected] (F. Incecik).
The hallmark of the disease on peripheral nerve biopsy is a giant axonal swelling due to massive accumulation of neurofilaments. Thus a generalized disorganization of intermediate filaments is indicated [3]. A major chromosomal locus for GAN maps to chromosome 16q24.1 and several disease causing mutations were identified in the gigaxonin (GAN) gene which is a member of the BTB/kelch protein superfamily [4]. These mutations result in loss of function of gigaxonin, an ubiquitously expressed protein. Gigaxonin stabilizes the microtubule network thus playing an important role in the cytoskeleton. Here we report the clinical manifestations and results of genetic study in eight Turkish patients with GAN.
http://dx.doi.org/10.1016/j.braindev.2014.12.002 0387-7604/Ó 2014 Published by Elsevier B.V. on behalf of The Japanese Society of Child Neurology.
Please cite this article in press as: Incecik F et al. Giant axonal disease: Report of eight cases. Brain Dev (2014), http://dx.doi.org/10.1016/ j.braindev.2014.12.002
2
F. Incecik et al. / Brain & Development xxx (2014) xxx–xxx
2. Material and methods We detected eight children diagnosed with GAN. GAN diagnosis was made both clinical and pathological findings. The data were retrospectively collected from the clinic files and included age, sex, consanguinity, family history of GAN, initial and clinical symptoms, investigation results on electroencephalogram (EEG), cerebral magnetic resonance imaging (MRI), nerve conduction studies, the nerve biopsy, and mutation analysis. Cerebral MRI were performed in all of patients. Nerve conduction studies were performed with surface stimulation and recording electrodes. Motor nerve conduction velocity studies (MNCVs) in the median and the peroneal nerves were recorded. Antidromic sensory action potential was recorded from the median nerve. Electromyography of the tibialis anterior and the first dorsalis interosseous muscle was performed with a concentric needle electrode. Electroencephalograms were performed in four patients. The nerve biopsy was performed in all of them. The nerve biopsy specimen was divided into two portions. One was fixed in 10% formalin and paraffin-embedded for standard examination. The other one was immediately fixed in Karnovsky’s fixative (containing 2.5% glutaraldehyde and 2% paraformaldehyde) and postfixed in 1% osmium tetroxide. Eponembedded one-micron thick sections stained with toluidin blue were prepared for light microscope examination. Mutation analysis could studied in two patients. The other parents did not accept genetic studies. 3. Results Among the 8 patients, 5 (62.5%) were girls and 3 (37.5%) were boys and the mean age on admission was 10. 13 ± 3.8 years (range: 5–15 years). Parental consanguinity was found in all the families. Patient 5 and 6 were siblings. The most severely affected sibling (patient 5) had generalized hypotonia, contractures of extremities, scoliosis, ptosis, nystagmus, feeding problems and excessive salivations. He could not walking. Second sibling had nystagmus, ataxic gait, dysmetria and dysdiadochokinesia. Two patients had contractures of extremities, and not walking (patient 1, 5). One patient was walking with aid (patient 8). The other patients were walking without aid. The all patients had kinky hair since early childhood (Fig. 1). Current patients had similar clinical presentation, compatible with a degenerative disease. Their clinical features showed in Table 1. All of them were born after an uneventful pregnancy and delivery. Onset of disease varied from 2 to 5 years of age. The initial complaint in all them were clumsy gait, falls, and weakness. Cerebellar abnormalities became apparent within a few years. Five patients had prominent cerebellar symptoms such as ataxia, nystagmus, and dysmetria.
Fig. 1. Typical kinky hair of patient 3.
MRI of the brain showed generalized both cerebral and cerebellar atrophy in two patients (patient 1, 5) and only cerebellar atrophy in two patients (patient 2, 8). White matter lesions were not found in all them. Electroencephalograms were performed in four patients, and they were normal. Nerve conduction studies showed predominantly axonal sensory-motor neuropathy in all patients. In the nerve biopsies, moderate myelinated nerve fibers loss, several regenerative clusters and multiple giant axons about 10–30 per funicle were shown in all of them. Giant axons were measured 25–40 micron in diameter. Focal demyelination, hypertrophic “onion bulb” changes and endoneurial fibrosis were also seen in the microscopic examination. Immunohistochemically neurofilament protein accumulation was detectable in giant axons (Fig. 2A and B). Mutation analysis was performed in two patients and IVS9 (+1G > T) (homozygous) mutation was detected. The findings of patients are summarized in Table 1. 4. Discussion Among the peripheral neuropathies in childhood, GAN shows some unique clinical and morphological features. Age at onset may be from soon after birth to up to 10 years of age, or older. The peripheral neuropathy presents with evidence of both motor and sensory involvement, with progressive weakness and hyporeflexia in the first seven years of life. Most patients become wheelchair dependent in the second decade of life and die in the third decade. They eventually become bedridden with severe polyneuropathy, ataxia, and dementia. Deaths results from secondary complications, such as respiratory failure. Early observations depicted clinical features of peripheral neuropathy in children with ‘remarkably kinky hair’. Affected children may develop symptoms that progress from clumsy gait to a pronounced difficulty to ambulate. Symptoms vary
Please cite this article in press as: Incecik F et al. Giant axonal disease: Report of eight cases. Brain Dev (2014), http://dx.doi.org/10.1016/ j.braindev.2014.12.002
F. Incecik et al. / Brain & Development xxx (2014) xxx–xxx
3
Table 1 Clinical and molecular data of the patients. Data
Patient 1
Patient 2
Patient 3
Patient 4
Patient 5
Patient 6
Patient 7
Patient 8
Age/sex Age at onset Initial symptoms
14/F 3 Weakness
15/M 4 Weakness
Yes No No
Yes Yes Yes (10 years)
11/F 5 Clumsy gait Yes No No
13/F 3.5 Clumsy gait Yes No No
8/F 2 Falls
Yes Yes Yes (9 years)
8/F 4 Clumsy gait Yes No No
5/M 3 Falls
Kinky hair Facial weakness Mental deterioration Scoliosis Ptosis Areflexia Cerebellar signs Babinski’s sign Peripheral neuropathy EEG abnormality Extremity deformities Motor capacity
12/M 5 Clumsy gait Yes No No
Yes No Yes (6 years)
Yes Yes Yes Yes Yes Yes
Yes No Yes Yes No Yes
No No Yes No No Yes
No No Yes No No Yes
Yes Yes Yes Yes Yes Yes
No No Yes Yes No Yes
No No Yes No No Yes
Yes Yes Yes Yes No Yes
No Yes
NP No
No No
NP No
No Yes
NP No
NP No
No No
WCB (12 years) Yes NP
Walking
Walking
Walking
Walking
Walking
Yes NP
Yes Yes
Yes Yes
WCB (12 years) Yes NP
Yes NP
Yes NP
Walking with aid Yes NP
Nerve biopsy GAN mutations
NP: not performed. WCB: wheelchair bound. Yes: performed.
Fig. 2. (A and B) Giant axons with aberrant neurofilament immunostaining on sural nerve biopsy of patient 5.
considerably. The typical clinical manifestations of GAN present with evidence of both motor and sensory involvement, including progressive and predominant distal clumsiness and muscle weakness, impaired sensation, absent tendon reflexes, and pronounced gait disturbance [1,5]. The diagnosis of GAN is suggested in individuals with following: (1) Severe early-onset peripheral motor and sensory neuropathy, (2) Tightly curled lackluster hair that differs markedly from that of the parents, (3) CNS involvement including intellectual disability, cerebellar signs, and pyramidal tract signs [5]. The cranial nerves can also be affected, especially the third and the seventh. Lesions in the brain, cerebellum
and spinal cord can cause mental retardation, dysmetria, seizures, nystagmus, and dysarthria, as well as signs of spasticity. Scoliosis, kyphosis, optic atrophy, ophthalmoplegia, and epilepsy are reported less commonly [1,6,7]. Involvement of the cerebral cortex, cerebellum, brainstem, anterior horn cells, and pyramidal tracts was also shown in postmortem studies of patients with GAN [4,8]. In the majority of reported GAN cases, CNS involvement is described early in the course of the disease. But, we detected diffuse cerebral and cerebellar atrophy in MRI only in four patients. There were no lesions of white matter disease. Unlikely sometimes, the symptoms and signs of CNS involvement can predominate. It is reported that even if there is no clinical
Please cite this article in press as: Incecik F et al. Giant axonal disease: Report of eight cases. Brain Dev (2014), http://dx.doi.org/10.1016/ j.braindev.2014.12.002
4
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sign of CNS involvement, there may be EEG and MRI abnormalities [6]. Some rare diseases may have to be considered in the differential diagnosis, such as severe early-onset hereditary neuropathies (CMT4A, CMT4B, CMT4C, CMT4E) and infantile neuroaxonal dystrophy, which has more evidence of cerebral involvement and more scattered lesions in the peripheral nerves differing, especially on ultramicroscopic examination, in their pathological appearance. In some CMT cases, typical giant axons may occur. Yet giant axonal neuropathy is a disorder affecting other intermediate filaments. In addition to axons, Schwann cells, cardiac muscle fibers, and hairs are characteristically involved. Other types of neuropathy have to be excluded, such as toxic neuropathies due to glue sniffing for example, vitamin B12 deficiency, diabetes mellitus and amyloid polyneuropathies [5,9]. When the CNS is affected, other types of spinocerebellar degeneration may cause difficulties, as well as Alexander disease, Fazio–Londe disease with cranial nerve involvement, and Menkes’ syndrome [2]. Menkes disease is a rare X-linked recessive disorder with prominent CNS involvement and hair changes resembling those of GAN. Patients with classic Menkes disease appear healthy until age two to three months, when loss of developmental milestones, hypotonia, seizures, and failure to thrive occur. The diagnosis is usually suspected when infants exhibit typical neurological changes and concomitant changes of hair [10]. The color of the hair is most often reported as white, silver or gray, a result of marked reduction of melanin and an associated abundance of tyrosinase. Clinically the hair appears short, sparse, coarse, lusterless and twisted. Hair shaft abnormalities include pilitorti and monilethrix, sometimes trichorrhexis and trichoptilosis. These structural changes are due to a defect in the copper-enzyme dependent cross-linkage of disulfide bands in the hair’s keratin. Kinky or curly hairs are characteristic clinical abnormality in patients with GAN. It usually appears in early years. But in the literature, they showed that presence of kinky or curly hairs was not a constant finding as patients with normal hair were described [11]. In typically GAN, children have curly hair and characteristic pilor alterations with pseudopili torti aspect occurring early in life before neuropathy is clinically present. All of our patients had the typical GAN phenotype with kinky hair. CNS involvement can cause epileptic seizures and mental deterioration. Mental deterioration was noted to start before the age of 10 years [2,12]. Our patients had normal mental status except for three. In EEG, disorganized background activity with focal spikes, spike-slow wave discharges, and paroxysmal slow wave activity were reported in literature [12,13]. None of our patients had seizures, we found not any EEG abnormalities in them. In GAN, histological findings in peripheral nerve biopsies, including those of autonomic nerves, include
enlarged axons with an accumulation of neurofilaments [2]. In fact, three types of filament are defective in this condition: neurofilaments, glial filaments, and intermediate filaments. The last are found in skin fibroblasts, Schwann cells, axons, and muscle fibers. The findings suggest that the disease may be caused by a generalized disorders of cytoplasmic microfilaments. Many onion bulb formations of Schwann cells are present [14]. In the CNS, as well as astrocytic degeneration, there is a loss of Purkinje cells and anterior horn cells. Brain demyelination has been reported, and Rosenthal fibers, so that Alexander’s disease may be suspected. Parts of the cerebrum most affected include the corticospinal tracts, the middle cerebellar peduncles, the posterior columns, and the olivocerebellar connections [15]. The gene for GAN was mapped to chromosome 16q24 [16]. Recently, the gene has been identified and found to encode for a novel, ubiquitously expressed protein named gigaxonin [17]. It has been suggested that the differences in the clinical presentation might be due to various mutations in the gene. Apart from these, in some families the disease has been reported not to be linked 16q24. In these patients, the disease has a slower progression with no signs of CNS involvement [18]. The previously reported Turkish patients, the 1502 + 1G > T and the R293X mutation were identified [4,11]. But, in our patients, IVS9 (+1G > T) (homozygous) mutation was found. We identified a novel homozygous mutation in the Turkish patients. Both of the patients had similar clinical findings, they had not pyramidal, cerebellar, and cranial nerve involvement yet. In conclusion, all GAN patients showed homogeneous clinical picture, mainly characterized by the involvement of neuroectodermal systems, including peripheral neuropathy, CNS features, and kinky hair. But, phenotypic heterogeneity of GAN is possible. In atypical cases and milder phenotypes, the presence of giant axons in nerve biopsy was helpful to specify molecular explorations. References [1] Igisu H, Ohta M, Tabira T, Hosokawa S, Goto I. Giant axonal neuropathy. A clinical entity affecting the central as well as the peripheral nervous system. Neurology 1975;25:717–21. [2] Ouvrier RA. Giant axonal neuropathy. A review. Brain Dev 1989;11:207–14. [3] Carpenter S, Karpati G, Andermann F, Gold R. Giant axonal neuropathy. A clinically and morphologically distinct neurological disease. Ann Neurol 1974;31:312–6. [4] Bomont P, Cavalier L, Blondeau F, Ben Hamida C, Belal S, Tazir M, et al. The gene encoding gigaxonin, a new member of the cytoskeletal BTB/kelch repeat family, is mutated in giant axonal neuropathy. Nat Genet 2000;26:370–4. [5] Tazir M, Nouioua S, Magy L, Huehne K, Assami S, Urtizberea A, et al. Phenotypic variability in giant axonal neuropathy. Neuromuscul Disord 2009;19:270–4. [6] Guazzi GC, Malandrini A, Gerli R, Federico A. Giant axonal neuropathy in 2 siblings: a generalized disorder of intermediate filaments. Eur Neurol 1991;31:50–6.
Please cite this article in press as: Incecik F et al. Giant axonal disease: Report of eight cases. Brain Dev (2014), http://dx.doi.org/10.1016/ j.braindev.2014.12.002
F. Incecik et al. / Brain & Development xxx (2014) xxx–xxx [7] Zhang LP, Zou LP. Clinical and genetic studies in a Chinese family with giant axonal neuropathy. J Child Neurol 2009;24:1552–6. [8] Kretzscmar HA, Berg BO, Davis RL. Giant axonal neuropathy: a neuropathological study. Acta Neuropathol 1987;73:138–44. [9] Zemmouri R, Azzedine H, Assami S, Kitouni N, Vallat JM, Maisonobe T, et al. Charcot–Marie–Tooth 2-like presentation of an Algerian family with giant axonal neuropathy. Neuromuscul Disord 2000;10:592–8. [10] Kodama H, Fujisawa C, Bhadhprasit W. Pathology, clinical features and treatments of congenital copper metabolic disordersfocus on neurologic aspects. Brain Dev 2011;33:243–51. [11] Sabatelli M, Bertini E, Servidei S, Fernandez E, Magi S, Tonali P. Giant axonal neuropathy: report on a case with focal fiber loss. Acta Neuropathol 1992;83:543–6. [12] Demir E, Bomont P, Erdem S, Cavalier L, Demirci M, Kose G, et al. Giant axonal neuropathy: clinical and genetic study in six cases. J Neurol Neurosurg Psychiatry 2005;76:825–32. [13] Lampl Y, Eshel Y, Ben-David E, Gilad R, Sarova-Pinhas I, Sandbank U. Giant axonal neuropathy with predominant central
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Please cite this article in press as: Incecik F et al. Giant axonal disease: Report of eight cases. Brain Dev (2014), http://dx.doi.org/10.1016/ j.braindev.2014.12.002
