Chana Vinkler

Significant overlap and possible identity of macrocephaly capillary malformation and megalencephaly polymicrogyria-polydactyly hydrocephalus syndromes.

We report on three patients with macrocephaly and polymicrogyria, and additional anomalies seen in megalencephaly polymicrogyria‐polydactyly hydrocephalus (MPPH) and macrocephaly capillary malformation (MCM) syndromes. Based on their characteristic brain malformations they were originally diagnosed with MPPH. In one patient the phenotype evolved during early infancy, and ultimately resulted in a diagnosis of MCM. A second was prenatally diagnosed with MPPH, but postnatally visualized capillary malformations led to a diagnosis of MCM. In a third, the original MPPH diagnosis was reconsidered after a critical review revealed additional subtle findings suggestive of MCM. Characteristic brain malformations are thought to distinguish between MPPH with perisylvian polymicrogyria, and MCM with megalencephaly with Chiari 1 malformation. However, polymicrogyria was reported in a significant number of patients with MCM. Conversely, upon review of imaging studies of patients with MPPH, we noted progressive crowding of the posterior fossa and acquired tonsillar herniation, a process deemed characteristic for MCM. Thus, neither polymicrogyria nor acquired tonsillar herniation are distinguishing features, and occur in both disorders. In addition to brain abnormalities, shared findings include cognitive impairment, coarse facial features and postaxial polydactyly. Facial nevus flammeus and cutis marmorata are most noticeable in infancy, and ligamentous laxity and redundant soft tissue are somewhat subjective findings. While asymmetric overgrowth is considered typical for MCM, it is not universally present. These variable and subtle findings can be identified in patients with MPPH. We propose that MPPH and MCM may not represent distinct entities and that the term MPPH‐CM syndrome be used to describe this spectrum.

A large homozygous deletion in the SAMHD1 gene causes atypical Aicardi―Goutiéres syndrome associated with mtDNA deletions

Aicardi–Goutiéres syndrome (AGS) is a genetic neurodegenerative disorder with clinical symptoms mimicking a congenital viral infection. Five causative genes have been described: three prime repair exonuclease1 (TREX1), ribonucleases H2A, B and C, and most recently SAM domain and HD domain 1 (SAMHD1). We performed a detailed clinical and molecular characterization of a family with autosomal recessive neurodegenerative disorder showing white matter destruction and calcifications, presenting in utero and associated with multiple mtDNA deletions. A muscle biopsy was normal and did not show any evidence of respiratory chain dysfunction. Southern blot analysis of tissue from a living child and affected fetuses demonstrated multiple mtDNA deletions. Molecular analysis of genes involved in mtDNA synthesis and maintenance (POLGα, POLGβ, Twinkle, ANT1, TK2, SUCLA1 and DGOUK) revealed normal sequences. Sequencing of TREX1 and ribonucleases H2A, B and C failed to reveal any mutations. Whole-genome homozygosity mapping revealed a candidate region containing the SAMHD1 gene. Sequencing of the gene in the affected child and two affected fetuses revealed a large deletion (9 kb), spanning the promoter, exon1 and intron 1. The parents were found to be heterozygous for this deletion. The identification of a homozygous large deletion in the SAMHD1 gene causing atypical AGS with multiple mtDNA deletions may add information regarding the involvement of mitochondria in self-activation of innate immunity by cell intrinsic components.

A novel missense mutation in the NDP gene in a child with Norrie disease and severe neurological involvement including infantile spasms

Norrie disease (ND) is a rare X‐linked recessive disorder characterized by congenital blindness and in some cases, mental retardation and deafness. Other neurological complications, particularly epilepsy, are rare. We report on a novel mutation identified in a patient with ND and profound mental retardation. The patient was diagnosed at the age of 6 months due to congenital blindness. At the age of 8 months he developed infantile spasms, which were diagnosed at 11 months as his EEG demonstrated hypsarrhythmia. Mutation analysis of the ND gene (NDP) of the affected child and his mother revealed a novel missense mutation at position c.134T > A resulting in amino acid change at codon V45E. To the best of our knowledge, such severe neurological involvement has not been previously reported in ND patients. The severity of the phenotype may suggest the functional importance of this site of the NDP gene.

Familial partial trisomy 15q11-13 presenting as intractable epilepsy in the child and schizophrenia in the mother.

Various rearrangements involve the proximal long arm of chromosome 15, including deletions, duplications, translocations, inversions and supernumerary marker chromosome of an inverted duplication. The large marker 15, that contains the Prader-Willi syndrome (PWS)/Angelman syndrome (AS) chromosome region, is usually associated with an abnormal phenotype of moderate to severe mental retardation, seizures, poor motor coordination, early-onset central hypotonia, autism and autistic-like behavior, schizophrenia and mild dysmorphic features. We report a ten year-old girl with normal intelligence prior to the onset of seizures, who developed severe intractable epilepsy at the age of seven years. Family history was significant for a mother with recurrent episodes of acute psychosis. The patients and mothers karyotype revealed 47,XX+m. Array comparative genomic hybridization (A-CGH) identified a gain of 13 BAC clones from 15q11.2 through 15q13.1, which was then confirmed by FISH to be part of the marker chromosome. This duplicated region contains the SNRPN/UBE3A locus. This case demonstrates that a duplication of 15q11-13 can present differently in the same family either as intractable epilepsy or as a psychiatric illness and that intelligence can be preserved. We suggest that CGH microarray should be performed in cases with intractable epilepsy or schizophrenia, with or without mental retardation.

Delineation of the interstitial 6q25 microdeletion syndrome: Refinement of the critical causative region†

Interstitial deletions of the long arm of chromosome 6 are rare. Clinically, this is a recognizable microdeletion syndrome associated with intellectual disability (ID), acquired microcephaly, typical dysmorphic features, structural anomalies of the brain, and nonspecific multiple organ anomalies. Most of the reported cases have cytogenetically visible interstitial deletions or subtelomeric microdeletions. We report on a boy with global developmental delay, distinct dysmorphic features, dysgenesis of the corpus callosum, limb anomalies, and genital hypoplasia who has a small interstitial deletion of the long arm of chromosome 6 detected by comparative genomic hybridization (CGH). The deleted region spans around 1 Mb of DNA and contains only two coding genes, ARID1B and ZDHHC14. To the best of our knowledge, this case represents the typical phenotype with the smallest deletion reported so far. We discuss the possible role of these genes in the phenotypic manifestations.

Mosaic marker chromosome 16 resulting in 16q11.2–q12.1 gain in a child with intellectual disability, microcephaly, and cerebellar cortical dysplasia†

Proximal duplications of the long arm of chromosome 16 are rare and only a few patients have been reported. Clinically, the patients do not have a distinctive syndromic appearance; however they all show some degree of intellectual disability and most have severely delayed speech development. We report on a child presenting with mild‐to‐moderate intellectual disability, microcephaly, language dyspraxia, and mild dysmorphisms who was found to have a mosaic gain of chromosome 16q (16q11.2–16q12.1). Magnetic resonance imaging done at the age of 4 years demonstrated cerebellar cortical dysplasia involving the vermis and hemispheres. This is the first report of cerebellar anomalies in a patient with partial trisomy 16q. The genes ZNF423 and CBLN1 found in the duplicated region play a role in the development of the cerebellum and may be responsible for the cerebellar cortical dysplasia.

A novel missense mutation in the Connexin 26 gene associated with autosomal recessive sensorineural deafness

Mutations in the Connexin 26 (Cx26) gene (GJB2) are a common cause of hereditary hearing impairment. We report the identification of a novel point mutation in the Cx26 gene, Leu205Pro(L205P), linked to familial, autosomal recessive sensorineural hearing loss. This missense mutation, causing amino acid leucine at position 205 to be substituted by proline, is located in the highly conserved sequence of the fourth transmembrane domain (TM4) of Cx26. Hearing loss with this mutation occurred in a Georgian Jewish family, was congenital, moderate to profound and nonprogressive. We have shown that the new mutation L205P in Cx26 is strongly associated with congenital NSHL. Multiple-sample screening for this mutation can be easily performed with a mismatch PCR that creates a restriction site.

Congenital Cytomegalovirus Infection Presenting as an Apparent Neurodegenerative Disorder

or developmental delay. With the increased identification of these lesions on magnetic resonance imaging (MRI), the differential diagnosis has broadened in recent years beyond leukodystrophic processes. Diseases that were thought to cause specific types of brain lesions are being found to present in a more varied way. Congenital cytomegalovirus infection is turning out to be a good example of this situation. We describe a case ofa young child in whom progressive microcephaly and marked white matter changes prompted an intensive diagnostic work-up, until cytomegalovirus infection was diagnosed. Patient Report

Severe growth deficiency, microcephaly, intellectual disability, and characteristic facial features are due to a homozygous QARS mutation

Glutaminyl tRNA synthase is highly expressed in the developing fetal human brain. Mutations in the glutaminyl-tRNA synthetase (QARS) gene have been reported in patients with progressive microcephaly, cerebral-cerebellar atrophy, and intractable seizures. We have previously reported a new recessive syndrome of severe linear growth retardation, poor weight gain, microcephaly, characteristic facial features, cutaneous syndactyly of the toes, high myopia, and intellectual disability in two sisters of Ashkenazi-Jewish origin (Eur J Med Genet 2014;57(6):288–92). Homozygosity mapping and whole exome sequencing revealed a homozygous missense (V476I) mutation in the QARS gene, located in the catalytic domain. The patient’s fibroblasts demonstrated markedly reduced QARS amino acylation activity in vitro. Furthermore, the same homozygous mutation was found in an unrelated girl of Ashkenazi origin with the same phenotype. The clinical presentation of our patients differs from the original QARS-associated syndrome in the severe postnatal growth failure, absence of epilepsy, and minor MRI findings, thus further expanding the phenotypic spectrum of the glutaminyl-tRNA synthetase deficiency syndromes.

A newly recognized syndrome of severe growth deficiency, microcephaly, intellectual disability, and characteristic facial features

Genetic syndromes with proportionate severe short stature are rare. We describe two sisters born to nonconsanguineous parents with severe linear growth retardation, poor weight gain, microcephaly, characteristic facial features, cutaneous syndactyly of the toes, high myopia, and severe intellectual disability. During infancy and early childhood, the girls had transient hepatosplenomegaly and low blood cholesterol levels that normalized later. A thorough evaluation including metabolic studies, radiological, and genetic investigations were all normal. Cholesterol metabolism and transport were studied and no definitive abnormality was found. No clinical deterioration was observed and no metabolic crises were reported. After due consideration of other known hereditary causes of post-natal severe linear growth retardation, microcephaly, and intellectual disability, we propose that this condition represents a newly recognized autosomal recessive multiple congenital anomaly-intellectual disability syndrome.