RESEARCH LETTER

4q21 Microdeletion in a Patient With Epilepsy and Brain Malformations Sho Yano,1,2* Meredithe McNamara,2 Sara Halbach,3 and Darrel Waggoner2,3 1

Section of Pediatric Neurology, Department of Pediatrics, University of Chicago Comer Children’s Hospital, Chicago, Illinios

2

Department of Pediatrics, University of Chicago Comer Children’s Hospital, Chicago, Illinios

3

Department of Human Genetics, University of Chicago, Chicago, Illinios

Manuscript Received: 4 September 2014; Manuscript Accepted: 18 November 2014

TO THE EDITOR: Microdeletion 4q21 syndrome involves a core phenotype of growth delay with preserved head circumference, neonatal hypotonia, severe developmental delay, small hands and feet, and distinctive facial features consisting of frontal bossing, hypertelorism, and short philtrum [Bonnet et al., 2010; Dukes-Rimsky et al., 2011]. A 1.37 Mb critical region, containing five genes, was defined in a group of nine patients [Bonnet et al., 2010]. Additional phenotypic features in some patients include brain malformations [Fagan & Gill, 1989; Dobyns et al., 2008; Bonnet et al., 2010; Kulharya et al., 1995; Nowaczyk et al., 1997], liver tumors [Terada et al., 2001], and renal cysts associated with PKD2 loss [Velinov et al., 2005]. Recently, a patient was described having a microdeletion involving 3 of the 5 genes in the critical region, resulting in a modified phenotype with no growth delay, no hypotonia, and only moderate developmental delay [Bhoj et al., 2013]. We report on an additional patient with a partial deletion of the critical region who nevertheless has growth delay, hypotonia, and developmental delay, as well as epilepsy, brain malformations, and feeding difficulties contributing to growth delay. He was the product of a naturally conceived singleton pregnancy, born spontaneously at 37 weeks. Pregnancy was complicated by maternal hypertension, anemia of unknown etiology requiring transfusion, and hyperemesis gravidarum. There were no known delivery complications. Apgar scores were 9 and 9 at 1 and 5 min. He was at the 50th centile for weight (2920 g) and 65th centile for length (48 cm). Family history was remarkable for childhood seizures in a paternal uncle and autism in distant cousins. Feeding difficulty was noted in infancy. He had frequent upper respiratory infections, reactive airway disease, and chronic cough. At age 25 months, he was diagnosed with central hypothyroidism and started on levothyroxine, although his TSH levels subsequently increased (0.21 mcU/ml at 28 mo, 3.91 mcU/ml at 29 mo.) ACTH and growth hormone stimulation tests were normal. He was followed by the Ophthalmology department for right optic nerve hypoplasia with poor visual fixation and right esotropia, which persisted despite patching. He had a simple febrile seizure at age 27 months, followed at age 28 months by generalized tonic-clonic status epilepticus requiring brief intubation. MRI of the brain and spine showed widespread moderate cortical atrophy and prominent ventricles. He had two subsequent hospitalizations for seizures

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How to Cite this Article: Yano S, McNamara M, Halbach S, Waggoner D. 2015. 4q21 Microdeletion in a patient with epilepsy and brain malformations. Am J Med Genet Part A 9999A:1–5.

and for right middle lobe pneumonia. Workups for inborn errors of metabolism and immunodeficiency were negative. Developmental delay was noted and he was able to lift his head at age 8 months, sat at age 1 year, crawled at 2 years, and said ’mama’ and ’dada’ at 20 months of age. At age 30 months, he was still unable to stand independently or to walk, had a good palmar but not pincer grasp, said three words, smiled socially, and offered toys. Feeding difficulties persisted despite speech therapy, and at age 30 months, his weight was 10.0 kg (
2.6 SD), length 83.6 cm (
2.7 SD), and OFC 47 cm (
1.5 SD). Speech evaluation with video swallow study confirmed oropharyngeal dysphagia with regurgitation, trace aspiration of thin liquids, and tracheal penetration with all consistencies of food. There was also significant upper airway obstruction from tonsillar hypertrophy interfering with adequate oral intake, and a tonsillectomy was performed. On evaluation at age 28 and 30 months, he had a broad forehead, hypertelorism, downslanting palpebral fissures, and left esotropia (Fig. 1). His hands and feet did not appear malformed or small. Neurological examination was remarkable for generalized hypotonia except for hypertonic ankles, with 3þ lower extremity reflexes, 7–8 beats ankle clonus bilaterally, and downgoing plantar reflexes. His karyotype was normal. Array CGH using the Affymetrix CytoScan HD microarray revealed a 1.6 Mb microdeletion



Correspondence to: Darrel Waggoner, 5841 S Maryland Ave; M/C0077, Chicago, IL 60637. E-mail: [email protected] Article first published online in Wiley Online Library (wileyonlinelibrary.com): 00 Month 2015 DOI 10.1002/ajmg.a.36910

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AMERICAN JOURNAL OF MEDICAL GENETICS PART A

FIG. 1. The patient at age 32 months, demonstrating his broad forehead with preserved OFC, hypertelorism, and downslanting palpebral fissures.

at chromosome 4q21, arr[hg19]4q21.22-q21.23 (82,681,767– 84,189,366) x1, which was confirmed by FISH. Our patient has typical features of microdeletion 4q21 syndrome associated with a partial deletion of the previously established critical region [Bonnet et al., 2010]. Three of the five genes from the critical region (HNRNPD, HNRPDL, ENOPH1) are included, along with 800 kb of distal sequence containing seven known protein-coding genes (TMEM150C, SCD5, SEC31A, LIN54, COPS4, PLAC8, COQ2). On the other hand, PRKG2 and RASGEF1B from the critical region are not deleted. These two genes have so far been the most promising candidates to account for the growth restriction and developmental delay, respectively. As previously noted, PRKG2-null mice have a dwarf phenotype, PRKG2 has been associated with idiopathic short stature in humans, and RASGEF1B is expressed in the central nervous system [Bonnet et al., 2010; Bhoj et al., 2013]. Furthermore, Patient 1 of Bhoj et al., who also has a partial 4q21 deletion sparing PRKG2 and RASGEF1B, has no growth restriction, no neonatal hypotonia, and relatively mild developmental delay with 8-month-old development at age 17 months [Bhoj et al., 2013; Patient 1]. The presence in our patient of severe growth restriction, hypotonia, and developmental delay, despite preserved copy number of both PRKG2 and RASGEF1B, suggests that these genes may not be solely responsible for the growth restriction and neurological features in microdeletion 4q21

syndrome. Our patient’s findings should be interpreted cautiously in light of his normal limb development, his feeding problems discussed below, the possibility that the deletion alters regulation of either gene, and the limitations of accurately predicting the breakpoints by microarray. Our patient’s neurological abnormalities appear to have contributed significantly to his poor growth by way of feeding difficulty. Laboratory evaluation revealed malnutrition, and clinically his oral intake was inadequate due to oropharyngeal dysmotility exacerbated by tonsillar hypertrophy with upper airway obstruction. Certainly, growth potential is limited in patients with microdeletion 4q21 syndrome: their reported heights and weights are uniformly low with widely varying OFCs (Supplementary Table I), delayed bone age was reported in the patient of Harada et al. [2002] and both of the patients who were described in adulthood reached final heights >5 SD below average [Dukes-Rimsky et al., 2011; Tsang et al., 2012]. On the other hand, feeding problems have been reported in several of these patients [McDermott et al., 1980; Nowaczyk et al., 1997; Dukes-Rimsky et al., 2011; Bhoj et al., 2013], and generalized hypotonia is near-universally present. Our patient’s course illustrates that poor weight gain in children with microdeletion 4q21 syndrome may still reflect treatable problems such as dysphagia and malnutrition, not necessarily primary growth restriction alone. The phenotype in our patient included extensive brain malformation with early seizures. Bonnet et al. [2010] noted that variable brain malformations might be a feature of the syndrome. We further suggest that epilepsy and neurological abnormalities attributable to the congenital brain malformation are common features of microdeletion 4q21 syndrome. We reviewed neuroimaging for our previously reported Patient 2 from Bhoj et al. [2013] and he has mild frontal atrophy, cerebellar tonsil ectopia, and slightly delayed myelination. MRIs for Patient 1 from that study (courtesy E. Bhoj) indicate prominent supratentorial extra-axial CSF spaces persisting through age 7.5 years with suspected atrophy, prominent lateral and 3rd ventricles, question of delayed myelination, a few tiny foci of T2 prolongation in the frontal subcortical white matter, slight dural thickening and enhancement over the frontal lobes, and cavum septum pellucidum. Review of the literature on patients with 4q21 microdeletions reveals not only that many patients have congenital brain malformations (such as cerebral/cerebellar atrophy, midline defects, and polymicrogyria), but also that clinical seizures or abnormal EEGs are quite common, being described in 10 patients (Table I). Hypotonia is a universal feature, and several patients are hypertonic in the lower extremities. We note that besides RASGEF1B, one further gene in the 4q21 region (ARHGAP24) could possibly contribute to the central nervous system phenotype in some patients. In a study of autism, Wis´niowiecka-Kowalnik et al., [2013] identified a patient with a 1-Mb 4q21 deletion containing only ARHGAP24; she had an abnormal EEG, autism with absent speech, and global cognitive deficits, with no reported dysmorphisms. ARHGAP24 does appear to be included in the deletion segment for several previously reported patients with microdeletion 4q21 syndrome, but it is well outside our patient’s deletion. We suggest that the microdeletion 4q21 syndrome includes a significant neurological component consisting of seizures, abnormal brain development, and hypotonia sometimes with lower extremity

arr[hg18]4q21.22-q21.23 (83,061,747–85,090,749) x1

arr[hg18]4q21.21-q21.23 (82,048,194–85,469,787) x1

Various sizes: 3.2–15.1 Mb

arr[hg18]4q21.3(81,055,150– 86,169,140) x1 and translocation1 arr[hg18]4q21.2-q23 (81,658,220–87,569,120) x1 and translocation1 4q21.1-q21.3 4q21.21–22.1

Bhoj et al. (2013) Patient 1

Bhoj et al. (2013) Patient 2

Bonnet et al. (2010) Case series (9 pts)

Dukes-Rimsky et al. (2011) Patient 1

4q21.22-q23 est.3 hg18:80– 84M – 99–102M

Suwa et al. (1998)/ Terada et al. (2001) Mitchell et al. (1981) Patient 7

4q21.1-q25

4q21.1-q22.1 4q21.1-q22.2 4q21.3-q23

arr[hg18]4q21.21-q22.1 (82,429,949–91,434,337) x1

Fagan & Gill (1989) Harada et al. (2002) Nowaczyk et al. (1997) Patient 1

Velinov et al. (2005) Dobyns et al. (2008) Patient LR04–022a2 Dobyns et al. (2008) Patient LR07–256 Tsang et al. (2012)

4q21.21–22.1

arr[hg19]4q21.22-q21.23 (82,681,767–84,189,366) x1

Our patient

Dukes-Rimsky et al. (2011) Patient 2

Extent of deletion

Description

NR

Autopsy: Absence of the corpus callosum NR MRI2 (6.5 mo): Partial agenesis of the CC, moderate CVH, small areas of polymicrogyria CT, MRI (3 mo?): Normal

NR MRI: Perisylvian polymicrogyria, suprasellar cyst, hydrocephalus, mega cisterna magna MRI: Perisylvian polymicrogyria, cerebellar vermis hypoplasia, dilated lateral ventricle CT (4 mo, 7 yrs): normal

NR

MRI (2.4 yrs): Extensive moderate atrophy Moderately prominent ventricles MRIs: Prominent extra-axial CSF spaces, lateral, and 3rd ventricles; suspected atrophy, cavum septum pellucidum, frontal subcortical white matter foci, slight dural enhancement MRI (2.1 yrs): Mild frontal atrophy, cerebellar tonsil ectopia, slightly delayed myelination 6/9 cerebral hypoplasia; 4/9 large ventricles; 3/9 cerebellar hypoplasia; 1/9 corpus callosum hypoplasia; 1/9 periventricular gliosis; 1 normal CT: normal

Neuroimaging

Frequent multifocal spikes Clonic seizures and apneas at 3 mo Apneas at 1 mo; GTC seizures at 3 mo Diffuse irritability, bilateral temporal irregular high-

Mild EEG abnormalities at 6 mo No seizures or epileptiform activities N/A NR NR

NR

NR Seizures at 3 months

Normal EEG

Seizures in 3/9 patients (neonatal in patients 3 and 7; at age 14 in patient 9) Normal EEG No seizures

None

GTC seizures at 2.2 yrs High-amplitude beta activity, slowing Normal EEG No confirmed seizures (twitches, resolved)

Seizures/EEG

TABLE I. Neurological Features of Patients With Deletions Involving 4q21

(Continued)

Hypotonia, decreased DTRs Aspiration from reflux at 1 mo; died at 5 mo Alternating exotropia

Generalized hypotonia Died at 5 mo (pneumonia)

Truncal hypotonia, mild extremity hypertonia Amblyopia, mildmoderate deficit on ABR Died at 13 hrs Hypotonia, ear canal stenosis, ? SNHL Hypotonia, 3þ DTRs, mildly abnormal VEP, oropharyngeal incoordination

Hypotonia Pale optic nerves, conductive hearing loss

Generalized hypotonia Minimal spasticity, normal DTRs Poor vision improved after cyst surgery

Weak cry Wheelchair-bound

Generalized hypotonia, 3þ DTRs all limbs Feeding problems (poor suck)

Poor suck, oral aversion, reflux

Right optic nerve hypoplasia with esotropia Central hypothyroid; no septo-optic dysplasia Intermittent esotropia; amblyopia

Clinical abnormalities

YANO ET AL. 3

hypertonia, and that multiple genes in the 4q21 region might be responsible.

ACKNOWLEDGMENT We thank Elizabeth Bhoj for neuroimaging information regarding her patient.

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2

1Patient 1 additionally had a translocation 46,XX,t(4;16)(q21.3;q24); patient 2 had 46,XX,t(6;10)(q22.1;q23.2) and a 0.89 Mb copy number loss on 7q31.33 (124,960,000–125,768,400). 2MRI findings as additionally reviewed by Dobyns et al. (2008). 3Estimated based on the reported FISH mapping: loss of 1 copy for BAC probes representing STS D4S2932 – D4S2986; 2 copies retained for D4S2964 proximally and D4S2966 distally.

REFERENCES

1

NR CT (0m), U/S (3m): High occipital encephalocele, right cerebellar hypoplasia, bilateral subependymal cysts 4q13.2–23

NR 4q13-q22

Mitchell et al. (1981) Patient 6 McDermott et al. (1980) Nowaczyk et al. (1997) patient 2

4q21.3-q26

Extensor spasms at 11 mo

Profound hypotonia Bilateral retinal hemorrhages, sluggish pupils Hypotonia, esotropia, auditory canal stenosis ’Very floppy’, poor feeding, L eye nystagmus Apneas Died at 7 mo (respiratory arrest) Intense EEG seizure activity at 7 wks No clinical seizures NR U/S (7 wks): Mild dilation of 3rd and LVs MRI (7 wks): Normal NR 4q21-q25

Kulharya et al. (1995) Patient 1 Rose et al. (1991)

4q21.1-q25

MRI (8 mo): Severe hydrocephalus

voltage spike bursts activated by sleep Neonatal seizures

Seizures/EEG TABLE I. (Continued )

Neuroimaging Extent of deletion Description

Died at 8 mo (cardiorespiratory arrest)

AMERICAN JOURNAL OF MEDICAL GENETICS PART A

Clinical abnormalities

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