Pediatric Neurology 50 (2014) 636e639
Contents lists available at ScienceDirect
Pediatric Neurology journal homepage: www.elsevier.com/locate/pnu
Clinical Observations
Acquired Microcephaly in Blepharophimosis-Ptosis-Epicanthus Inversus Syndrome Because of an Interstitial 3q22.3q23 Deletion Sarah J. Dean MD a, *, Kenton R. Holden MD b, c, Alka Dwivedi PhD c, Barbara R. Dupont PhD c, Michael J. Lyons MD c a
College of Medicine, Medical University of South Carolina, Charleston, South Carolina Neurosciences (Neurology) and Pediatrics, Medical University of South Carolina, Charleston, South Carolina c Greenwood Genetic Center, Greenwood, South Carolina b
abstract BACKGROUND: Blepharophimosis-ptosis-epicanthus inversus syndrome is an autosomal dominant condition because of mutations or deletions of the FOXL2 gene. Microcephaly is not associated with FOXL2 mutations but has been reported in individuals with chromosome 3q deletions, which include the FOXL2 gene and other contiguous genes. The ATR gene has been reported as a candidate gene for microcephaly in individuals with contiguous deletion of chromosome 3q involving the FOXL2 gene. PATIENT: We describe a girl with blepharophimosis-ptosisepicanthus inversus syndrome along with acquired microcephaly and intellectual disability. RESULTS: Our patient had a deletion of chromosome 3q22.2q23, which does not include the ATR gene but does include the PIK3CB gene as a candidate gene for microcephaly. CONCLUSION: We propose that the PIK3CB gene included in our patient’s chromosome 3q deletion may be the gene responsible for microcephaly and other patients with blepharophimosis-ptosis-epicanthus inversus syndrome because of a chromosome 3q deletion. Keywords: blepharophimosis-ptosis-epicanthus inversus, microcephaly, PIK3CB, deletion
Pediatr Neurol 2014; 50: 636-639 Ó 2014 Elsevier Inc. All rights reserved.
Introduction
Blepharophimosis-ptosis-epicanthus inversus syndrome (BPES) is a rare autosomal dominant disorder attributed to mutation or deletion of the FOXL2 gene located at chromosome 3q23. Individuals affected with this syndrome present clinically with complex eyelid malformations, including small palpebral fissures, increased inner canthal measurement, small skinfolds running upward and inward from the lower eyelids, and drooping eyelids (ptosis).1 Two types of BPES have been described. Type 1 BPES is defined as patients with the four major eyelid malformations and premature ovarian failure. Type 2 BPES refers to individuals with only the four major eyelid malformations.2 The Article History: Received July 29, 2013; Accepted in final form January 18, 2014 * Communications should be addressed to: Dr. Sarah J. Dean; 2301; Vanderbilt University Hospital; Nashville, TN 37232. E-mail address: [email protected] 0887-8994/$ - see front matter Ó 2014 Elsevier Inc. All rights reserved. http://dx.doi.org/10.1016/j.pediatrneurol.2014.01.055
diagnosis of BPES can be confirmed by identifying a mutation or deletion of either the FOXL2 gene or a FOXL2 regulatory region.3,4 Deletions of FOXL2 gene are associated with approximately 12% of BPES cases.4 Beyond the distinct facial appearance in BPES, there is a large degree of phenotypic variability in individuals with FOXL2 deletions. Additional clinical findings, including microcephaly, appear to be more common in patients with larger deletions of chromosome 3q beyond the FOXL2 region.5 The ATR gene has been proposed as a candidate gene for microcephaly in patients with BPES because of deletions of chromosome 3q.6 This was supported by the prior identification of a homozygous ATR mutation in two consanguineous Pakistani families with Seckel syndrome, a genetic condition associated with primary microcephaly.7 Furthermore, impaired ATR signaling was detected from a cell line of an individual with BPES and microcephaly because of a deletion including the FOXL2 and ATR genes.8 However, as Seckel syndrome is an autosomal recessive disorder, it was felt that combined haploinsufficiency of the
S.J. Dean et al. / Pediatric Neurology 50 (2014) 636e639
ATR gene and an additional gene may be necessary to cause microcephaly.8 We present a patient with BPES and acquired microcephaly because of a chromosome 3q deletion, which does not include the ATR gene. We propose instead that the deletion of the PIK3CB gene may be responsible for acquired microcephaly in our patient. Clinical report
Our patient is a 7-year-old girl who was evaluated because of mild intellectual disability and facial dysmorphism. She was the only child born to healthy, nonconsanguineous parents. Her family history was significant for three paternal uncles with autism spectrum disorder. There are no family members with microcephaly, seizures, or facial features of BPES. She was born at 36 weeks’ gestational age via cesarean section secondary to nonreassuring fetal status following a maternal hypertensive episode. Her birth weight was 2.24 kg (15th percentile). Her birth length was 47.5 cm (40th percentile). Her birth head circumference was 31.6 cm (20th percentile). Her head circumference at age 3 years was 45 cm (less than third percentile and 50th percentile for 12 months old). Her past medical history was significant for complex partial seizures at age 3 years. Electroencephalography revealed left occipital epileptiform discharges. She had a normal brain magnetic resonance imaging at age 7 years. Her seizures are currently well controlled with lamotrigine 125 mg per day. At age 5 years, she underwent three eyelid surgeries to correct a significant visual field loss caused by ptosis. Her early major neurodevelopmental milestones were normal, although she had difficulty with social interactions. Psychoeducational testing at age 7 years revealed a full-scale IQ of 68 on the Wechsler Intelligence Scale for Childrendfourth edition. She was in the first grade with half of her time in regular classes and half of her time in resource classes. She was also receiving speech therapy.
637
During her initial genetic evaluation at age 7 years, she was anxious but cooperative with mild neurodevelopmental delay. Her hearing was intact. She did not display a significant amount of spontaneous speech but could answer simple questions. Her height was 117.5 cm (10th percentile), weight was 19.5 kg (fifth percentile), and head circumference was 47.2 cm (less than third percentile and 50th percentile for 20 months old). Her physical examination revealed microcephaly, underdeveloped supraorbital ridges, small posteriorly rotated ears with overfolded helices, fullness of the lateral eyebrows, and short palpebral fissures with blepharophimosis and ptosis statusepostsurgical correction (Fig 1AC). She had an inner canthal measurement of 2.9 cm (50th percentile), interpupillary distance of 4.9 cm (10th-25th percentile), outer canthal distance of 7 cm (less than third percentile), and palpebral fissure length of 1.9 cm bilaterally (less than third percentile). The remainder of her physical examination was normal. Her neurological examination including cranial nerves, muscle mass, motor functions, coordination, and reflexes was normal with no evidence of focal neurological deficits. Because of physical examination findings suggestive of BPES along with acquired microcephaly, there was concern for the deletion of chromosome 3q. Chromosome analysis and array comparative genomic hybridization analysis revealed a 3.76 Mb deletion on chromosome 3q22.3q23 (136,739,558-140,496,967), which included the FOXL2 gene (Fig 2). Fluorescence in situ hybridization studies using the RP11-220J13 bacterial artificial chromosome probe confirmed the deletion (Fig 3). The parental test results were normal, indicating that this is a de novo chromosome 3q22.3q23 deletion in our patient. Discussion
Our patient presented with BPES, mild intellectual disability, acquired microcephaly, and well-controlled complex partial epilepsy. Genetic studies demonstrated a de novo chromosome 3q22.3q23 deletion, which is thought
FIGURE 1. (A and B) The patient at an age of 7 years with underdeveloped supraorbital ridges, fullness of the lateral eyebrows, short palpebral fissures with blepharophimosis, and ptosis statusepostsurgical correction. (C) Small posteriorly rotated ear with overfolded helix. (Color version of figure is available in the online edition.)
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S.J. Dean et al. / Pediatric Neurology 50 (2014) 636e639
FIGURE 2. Results of Oxford Gene Technology’s syndrome plus microarray: Genomic dosage for the patient (green) and a reference DNA (red) were measured by the log2 ratio of normalized probe intensities. A 3.76-Mb copy number loss of chromosome 3q22.3q23 between positions 136,739,558 and 140,496,967 (NCBI36/hg18) was identified in our patient. A screenshot from the University of California Santa Cruz genome browser depicts the genes within the breakpoints of the deleted region of chromosome 3q, which includes the FOXL2 and PIK3CB genes, but not the ATR gene. (Color version of figure is available in the online edition.)
to be responsible for the clinical features in our patient. Patients with a deletion or mutation restricted to the FOXL2 gene present with eyelid malformations. Individuals with larger deletions of chromosome 3q often have additional clinical features, including microcephaly. This has led to an interest in determining which gene in the deleted region is responsible for microcephaly. The deletion of the ATR gene has previously been reported to cause microcephaly in individuals with a chromosome 3q deletion presenting with BPES and additional
FIGURE 3. Fluorescence in situ hybridization analysis: Representative fluorescence in situ hybridization image indicating the loss (absence of green signal) of RP11-220J13 bacterial artificial chromosome probe (chromosome 3: 136,799,822-136,965,535; hg 18) specific for chromosome 3q22.2. The centromere of chromosome 3 is indicated in red. (Color version of figure is available in the online edition.)
clinical features.6 The ATR gene is a member of the PI3 kinaseelike kinase family, which, in response to DNA damage, leads to cell cycle arrest and has been associated with activation of the Akt pathway.9 The ATR gene was not found to be included in our patient’s deleted region of chromosome 3q. Deletions of regulatory elements can impact the expression of a gene not included in the deletion.4 However, the ATR gene is located >3 Mb away from our patient’s deletion, making it unlikely the ATR gene is affected by the deletion. As a result, we hypothesize that a different gene included in our patient’s chromosome 3q deletion may be responsible for her acquired microcephaly. Our patient’s chromosome 3q deletion involves >20 other genes, including the NCK1, SOX14, and PIK3CB genes. The NCK1 gene has been demonstrated to be involved in spinal cord development, but a mouse model lacking both copies of the NCK1 gene did not display any brain anomalies.10 SOX14 expression occurs in the neural tube and apical ectodermal ridge.11 The SOX14 gene has been proposed as a candidate for limb anomalies associated with BPES.11 The PIK3CB gene is located
Contents lists available at ScienceDirect
Pediatric Neurology journal homepage: www.elsevier.com/locate/pnu
Clinical Observations
Acquired Microcephaly in Blepharophimosis-Ptosis-Epicanthus Inversus Syndrome Because of an Interstitial 3q22.3q23 Deletion Sarah J. Dean MD a, *, Kenton R. Holden MD b, c, Alka Dwivedi PhD c, Barbara R. Dupont PhD c, Michael J. Lyons MD c a
College of Medicine, Medical University of South Carolina, Charleston, South Carolina Neurosciences (Neurology) and Pediatrics, Medical University of South Carolina, Charleston, South Carolina c Greenwood Genetic Center, Greenwood, South Carolina b
abstract BACKGROUND: Blepharophimosis-ptosis-epicanthus inversus syndrome is an autosomal dominant condition because of mutations or deletions of the FOXL2 gene. Microcephaly is not associated with FOXL2 mutations but has been reported in individuals with chromosome 3q deletions, which include the FOXL2 gene and other contiguous genes. The ATR gene has been reported as a candidate gene for microcephaly in individuals with contiguous deletion of chromosome 3q involving the FOXL2 gene. PATIENT: We describe a girl with blepharophimosis-ptosisepicanthus inversus syndrome along with acquired microcephaly and intellectual disability. RESULTS: Our patient had a deletion of chromosome 3q22.2q23, which does not include the ATR gene but does include the PIK3CB gene as a candidate gene for microcephaly. CONCLUSION: We propose that the PIK3CB gene included in our patient’s chromosome 3q deletion may be the gene responsible for microcephaly and other patients with blepharophimosis-ptosis-epicanthus inversus syndrome because of a chromosome 3q deletion. Keywords: blepharophimosis-ptosis-epicanthus inversus, microcephaly, PIK3CB, deletion
Pediatr Neurol 2014; 50: 636-639 Ó 2014 Elsevier Inc. All rights reserved.
Introduction
Blepharophimosis-ptosis-epicanthus inversus syndrome (BPES) is a rare autosomal dominant disorder attributed to mutation or deletion of the FOXL2 gene located at chromosome 3q23. Individuals affected with this syndrome present clinically with complex eyelid malformations, including small palpebral fissures, increased inner canthal measurement, small skinfolds running upward and inward from the lower eyelids, and drooping eyelids (ptosis).1 Two types of BPES have been described. Type 1 BPES is defined as patients with the four major eyelid malformations and premature ovarian failure. Type 2 BPES refers to individuals with only the four major eyelid malformations.2 The Article History: Received July 29, 2013; Accepted in final form January 18, 2014 * Communications should be addressed to: Dr. Sarah J. Dean; 2301; Vanderbilt University Hospital; Nashville, TN 37232. E-mail address: [email protected] 0887-8994/$ - see front matter Ó 2014 Elsevier Inc. All rights reserved. http://dx.doi.org/10.1016/j.pediatrneurol.2014.01.055
diagnosis of BPES can be confirmed by identifying a mutation or deletion of either the FOXL2 gene or a FOXL2 regulatory region.3,4 Deletions of FOXL2 gene are associated with approximately 12% of BPES cases.4 Beyond the distinct facial appearance in BPES, there is a large degree of phenotypic variability in individuals with FOXL2 deletions. Additional clinical findings, including microcephaly, appear to be more common in patients with larger deletions of chromosome 3q beyond the FOXL2 region.5 The ATR gene has been proposed as a candidate gene for microcephaly in patients with BPES because of deletions of chromosome 3q.6 This was supported by the prior identification of a homozygous ATR mutation in two consanguineous Pakistani families with Seckel syndrome, a genetic condition associated with primary microcephaly.7 Furthermore, impaired ATR signaling was detected from a cell line of an individual with BPES and microcephaly because of a deletion including the FOXL2 and ATR genes.8 However, as Seckel syndrome is an autosomal recessive disorder, it was felt that combined haploinsufficiency of the
S.J. Dean et al. / Pediatric Neurology 50 (2014) 636e639
ATR gene and an additional gene may be necessary to cause microcephaly.8 We present a patient with BPES and acquired microcephaly because of a chromosome 3q deletion, which does not include the ATR gene. We propose instead that the deletion of the PIK3CB gene may be responsible for acquired microcephaly in our patient. Clinical report
Our patient is a 7-year-old girl who was evaluated because of mild intellectual disability and facial dysmorphism. She was the only child born to healthy, nonconsanguineous parents. Her family history was significant for three paternal uncles with autism spectrum disorder. There are no family members with microcephaly, seizures, or facial features of BPES. She was born at 36 weeks’ gestational age via cesarean section secondary to nonreassuring fetal status following a maternal hypertensive episode. Her birth weight was 2.24 kg (15th percentile). Her birth length was 47.5 cm (40th percentile). Her birth head circumference was 31.6 cm (20th percentile). Her head circumference at age 3 years was 45 cm (less than third percentile and 50th percentile for 12 months old). Her past medical history was significant for complex partial seizures at age 3 years. Electroencephalography revealed left occipital epileptiform discharges. She had a normal brain magnetic resonance imaging at age 7 years. Her seizures are currently well controlled with lamotrigine 125 mg per day. At age 5 years, she underwent three eyelid surgeries to correct a significant visual field loss caused by ptosis. Her early major neurodevelopmental milestones were normal, although she had difficulty with social interactions. Psychoeducational testing at age 7 years revealed a full-scale IQ of 68 on the Wechsler Intelligence Scale for Childrendfourth edition. She was in the first grade with half of her time in regular classes and half of her time in resource classes. She was also receiving speech therapy.
637
During her initial genetic evaluation at age 7 years, she was anxious but cooperative with mild neurodevelopmental delay. Her hearing was intact. She did not display a significant amount of spontaneous speech but could answer simple questions. Her height was 117.5 cm (10th percentile), weight was 19.5 kg (fifth percentile), and head circumference was 47.2 cm (less than third percentile and 50th percentile for 20 months old). Her physical examination revealed microcephaly, underdeveloped supraorbital ridges, small posteriorly rotated ears with overfolded helices, fullness of the lateral eyebrows, and short palpebral fissures with blepharophimosis and ptosis statusepostsurgical correction (Fig 1AC). She had an inner canthal measurement of 2.9 cm (50th percentile), interpupillary distance of 4.9 cm (10th-25th percentile), outer canthal distance of 7 cm (less than third percentile), and palpebral fissure length of 1.9 cm bilaterally (less than third percentile). The remainder of her physical examination was normal. Her neurological examination including cranial nerves, muscle mass, motor functions, coordination, and reflexes was normal with no evidence of focal neurological deficits. Because of physical examination findings suggestive of BPES along with acquired microcephaly, there was concern for the deletion of chromosome 3q. Chromosome analysis and array comparative genomic hybridization analysis revealed a 3.76 Mb deletion on chromosome 3q22.3q23 (136,739,558-140,496,967), which included the FOXL2 gene (Fig 2). Fluorescence in situ hybridization studies using the RP11-220J13 bacterial artificial chromosome probe confirmed the deletion (Fig 3). The parental test results were normal, indicating that this is a de novo chromosome 3q22.3q23 deletion in our patient. Discussion
Our patient presented with BPES, mild intellectual disability, acquired microcephaly, and well-controlled complex partial epilepsy. Genetic studies demonstrated a de novo chromosome 3q22.3q23 deletion, which is thought
FIGURE 1. (A and B) The patient at an age of 7 years with underdeveloped supraorbital ridges, fullness of the lateral eyebrows, short palpebral fissures with blepharophimosis, and ptosis statusepostsurgical correction. (C) Small posteriorly rotated ear with overfolded helix. (Color version of figure is available in the online edition.)
638
S.J. Dean et al. / Pediatric Neurology 50 (2014) 636e639
FIGURE 2. Results of Oxford Gene Technology’s syndrome plus microarray: Genomic dosage for the patient (green) and a reference DNA (red) were measured by the log2 ratio of normalized probe intensities. A 3.76-Mb copy number loss of chromosome 3q22.3q23 between positions 136,739,558 and 140,496,967 (NCBI36/hg18) was identified in our patient. A screenshot from the University of California Santa Cruz genome browser depicts the genes within the breakpoints of the deleted region of chromosome 3q, which includes the FOXL2 and PIK3CB genes, but not the ATR gene. (Color version of figure is available in the online edition.)
to be responsible for the clinical features in our patient. Patients with a deletion or mutation restricted to the FOXL2 gene present with eyelid malformations. Individuals with larger deletions of chromosome 3q often have additional clinical features, including microcephaly. This has led to an interest in determining which gene in the deleted region is responsible for microcephaly. The deletion of the ATR gene has previously been reported to cause microcephaly in individuals with a chromosome 3q deletion presenting with BPES and additional
FIGURE 3. Fluorescence in situ hybridization analysis: Representative fluorescence in situ hybridization image indicating the loss (absence of green signal) of RP11-220J13 bacterial artificial chromosome probe (chromosome 3: 136,799,822-136,965,535; hg 18) specific for chromosome 3q22.2. The centromere of chromosome 3 is indicated in red. (Color version of figure is available in the online edition.)
clinical features.6 The ATR gene is a member of the PI3 kinaseelike kinase family, which, in response to DNA damage, leads to cell cycle arrest and has been associated with activation of the Akt pathway.9 The ATR gene was not found to be included in our patient’s deleted region of chromosome 3q. Deletions of regulatory elements can impact the expression of a gene not included in the deletion.4 However, the ATR gene is located >3 Mb away from our patient’s deletion, making it unlikely the ATR gene is affected by the deletion. As a result, we hypothesize that a different gene included in our patient’s chromosome 3q deletion may be responsible for her acquired microcephaly. Our patient’s chromosome 3q deletion involves >20 other genes, including the NCK1, SOX14, and PIK3CB genes. The NCK1 gene has been demonstrated to be involved in spinal cord development, but a mouse model lacking both copies of the NCK1 gene did not display any brain anomalies.10 SOX14 expression occurs in the neural tube and apical ectodermal ridge.11 The SOX14 gene has been proposed as a candidate for limb anomalies associated with BPES.11 The PIK3CB gene is located
