Linda Manwaring

Fabry disease in infancy and early childhood: a systematic literature review

Purpose:Fabry disease is a pan-ethnic, progressive, X-linked genetic disorder that commonly presents in childhood and is caused by deficient activity of the lysosomal enzyme alpha-galactosidaseA (α-gal A). Symptoms of Fabry disease in the pediatric population are well described for patients over five years of age; however, data are limited for infancy and early childhood. The purpose of this article is to delineate the age of detection for specific Fabry symptoms in early childhood.Methods:A systematic retrospective analysis of PubMed indexed, peer-reviewed publications and case reports in the pediatric Fabry population was performed to review symptoms in patients reported before 5 years of age.Results:The most frequently reported symptom in all age groups under 5 years was acroparesthesias/neuropathic pain, reported in 9 children, ranging in age from 2.0-4.0 years. Also notable is the frequency of gastrointestinal issues reported in 6 children aged 1.0-4.1 years of age.Conclusion:This article finds clear evidence that symptoms can occur in early childhood, before age 5 years. Given early presenting symptoms and the ability to monitor these disease hallmarks, a timely referral to a medical geneticist or other specialty clinician experienced in managing children with Fabry disease is strongly indicated.Genet Med 17 5, 323–330.

Int22h-1/int22h-2-mediated Xq28 rearrangements: intellectual disability associated with duplications and in utero male lethality with deletions

Background X linked intellectual disability (XLID) is common, with an estimated prevalence of 1/1000. The expanded use of array comparative genomic hybridisation (CGH) has led to the identification of several XLID-associated copy-number variants. Methods Array CGH analysis was performed using chromosomal microarray with ∼105 000 oligonucleotides covering the entire genome. Confirmatory fluorescence in situ hybridisation analyses were subsequently performed. Chromosome X-inactivation (XCI) was assessed using methylation-sensitive restriction enzyme digestion followed by PCR amplification. Results A novel ∼0.5 Mb duplication in Xq28 was identified in four cognitively impaired males who share behavioural abnormalities (hyperactivity and aggressiveness) and characteristic facial features (high forehead, upper eyelid fullness, broad nasal bridge and thick lower lip). These duplications were inherited from mothers with skewed XCI and are mediated by nonallelic homologous recombination between the low-copy repeat regions int22h-1 and int22h-2, which, in addition to int22h-3, are also responsible for inversions disrupting the factor VIII gene in haemophilia A. In addition, we have identified a reciprocal deletion in a girl and her mother, both of whom exhibit normal cognition and completely skewed XCI. The mother also had two spontaneous abortions. Conclusions The phenotypic similarities among subjects with int22h-1/int22h-2-mediated Xq28 duplications suggest that such duplications are responsible for a novel XLID syndrome. The reciprocal deletion may not be associated with a clinical phenotype in carrier females due to skewed XCI, but may be lethal for males in utero. Advancements in array CGH technology have enabled the identification of such small, clinically relevant copy-number variants.

Haploinsufficiency of ZNF238 is associated with corpus callosum abnormalities in 1q44 deletions.

A variety of candidate genes have been proposed to cause corpus callosum abnormalities (CCAs) in patients with terminal chromosome 1q deletions. Recent data excluded AKT3 and implicated ZNF238 and/or CEP170 as genes causative of corpus callosum anomalies in patients with 1q43–1q44 deletions. We report on a girl with dysmorphic features, seizures beginning in infancy, hypotonia, marked developmental delay, and dysgenesis of the corpus callosum. Chromosomal microarray analysis detected a de novo 1.47 Mb deletion at 1q44. The deleted interval encompasses the ZNF238 gene but not the CEP170 or AKT3 genes, thus providing additional evidence for the former and against the latter as being causative of corpus callosum anomalies in patients with such deletions.

NR2F1 haploinsufficiency is associated with optic atrophy, dysmorphism and global developmental delay.

NR2F1 Haploinsufficiency is Associated With Optic Atrophy, Dysmorphism and Global Developmental Delay Hussam Al-Kateb, Joshua S Shimony, Marisa Vineyard, Linda Manwaring, Shashikant Kulkarni, and Marwan Shinawi* Department of Pathology and Immunology, Washington University School of Medicine, St. Louis, Missouri Mallinckrodt Institute of Radiology, Washington University School of Medicine, St. Louis, Missouri Department of Pediatrics, Division of Genetics and Genomic Medicine, Washington University School of Medicine, St. Louis, Missouri

The Exome Clinic and the role of medical genetics expertise in the interpretation of exome sequencing results

Purpose:Evaluation of the clinician’s role in the optimal interpretation of clinical exome sequencing (ES) results.Methods:Retrospective chart review of the first 155 patients who underwent clinical ES in our Exome Clinic and direct interaction with the ordering geneticist to evaluate the process of interpretation of results.Results:The most common primary indication was neurodevelopmental problems (~66%), followed by multiple congenital anomalies (~10%). Based on sequencing data, the overall diagnostic yield was 36%. After assessment by the medical geneticist, incorporation of detailed phenotypic and molecular data, and utilization of additional diagnostic modalities, the final diagnostic yield increased to 43%. Seven patients in our cohort were included in initial case series that described novel genetic syndromes, and 23% of patients were involved in subsequent research studies directly related to their results or involved in efforts to move beyond clinical ES for diagnosis. Clinical management was directly altered due to the ES findings in 12% of definitively diagnosed cases.Conclusions:Our results emphasize the usefulness of ES, demonstrate the significant role of the medical geneticist in the diagnostic process of patients undergoing ES, and illustrate the benefits of postanalytical diagnostic work-up in solving the “diagnostic odyssey.” Genet Med advance online publication 02 March 2017

WAC loss-of-function mutations cause a recognisable syndrome characterised by dysmorphic features, developmental delay and hypotonia and recapitulate 10p11.23 microdeletion syndrome

Background Rare de novo mutations have been implicated as a significant cause of idiopathic intellectual disability. Large deletions encompassing 10p11.23 have been implicated in developmental delay, behavioural abnormalities and dysmorphic features, but the genotype–phenotype correlation was not delineated. Mutations in WAC have been recently reported in large screening cohorts of patients with intellectual disability or autism, but no full phenotypic characterisation was described. Methods Clinical and molecular characterisation of six patients with loss-of-function WAC mutations identified by whole exome sequencing was performed. Clinical data were obtained by retrospective chart review, parental interviews, direct patient interaction and formal neuropsychological evaluation. Results Five heterozygous de novo WAC mutations were identified in six patients. Three of the mutations were nonsense, and two were frameshift; all are predicted to cause loss of function either through nonsense-mediated mRNA decay or protein truncation. Clinical findings included developmental delay (6/6), hypotonia (6/6), behavioural problems (5/6), eye abnormalities (5/6), constipation (5/6), feeding difficulties (4/6), seizures (2/6) and sleep problems (2/6). All patients exhibited common dysmorphic features, including broad/prominent forehead, synophrys and/or bushy eyebrows, depressed nasal bridge and bulbous nasal tip. Posteriorly rotated ears, hirsutism, deep-set eyes, thin upper lip, inverted nipples, hearing loss and branchial cleft anomalies were also noted. Conclusions Our case series show that loss-of-function mutations in WAC cause a recognisable genetic syndrome characterised by a neurocognitive phenotype and facial dysmorphism. Our data highly suggest that WAC haploinsufficiency is responsible for most of the phenotypic features associated with deletions encompassing 10p11.23.

Multigenerational autosomal dominant inheritance of 5p chromosomal deletions.

Deletion of the short arm of chromosome 5 (5p‐) is associated with phenotypic features including a cat‐like cry in infancy, dysmorphic facial features, microcephaly, and intellectual disability, and when encompassing a minimal critical region, may be defined as Cri‐du‐Chat syndrome (CdCS). Most 5p deletions are de novo in origin, and familial cases are often associated with translocation and inversion. Herein, we report three multigenerational families carrying 5p terminal deletions of different size transmitted in an autosomal dominant manner causing variable clinical findings. Terminal 5p deletions and the mode of inheritance were clinically characterized and molecularly analyzed by a combination of microarray and fluorescence in situ hybridization analyses. Shared phenotypic features documented in this cohort included neuropsychiatric findings, poor growth, and dysmorphic facial features. This study supports newly recognized effects of aberrant SEMA5A and CTNND2 dosage on severity of autistic and cognitive phenotypes. Comparative analysis of the breakpoints narrows the critical region for the cat‐like cry down to an interval less than 1 Mb encompassing a candidate gene ICE1, which regulates small nuclear RNA transcription. This study also indicates that familial terminal 5p deletion is a rare presentation displaying intra‐ and inter‐familial phenotypic variability, the latter of which may be attributed to size and gene content of the deletion. The observed intra‐familial phenotypic heterogeneity suggests that additional modifying elements including genetic and environmental factors may have an impact on the clinical manifestations observed in 5p deletion carriers, and in time, further high resolution studies of 5p deletion breakpoints will continue to aid in defining genotype–phenotype correlations.