👤 Katta M Girisha

Agrin, encoded by AGRN , plays a vital role in the acetylcholine receptor clustering pathway, and any defects in this pathway are known to cause congenital myasthenic syndrome (CMS) 8 in early childhood with variable fatigable muscle weakness. The most severe or lethal form of CMS manifests as a fetal akinesia deformation sequence (FADS). To date, only one family has been reported with an association of null variants in AGRN and a lethal FADS. We identified a nonconsanguineous couple with recurrent pregnancy loss. Detailed phenotyping of fetuses was performed via perinatal autopsy. Genetic evaluation was performed along with split-read analysis to identify variants. Perinatal phenotyping revealed FADS in the family, and genomic testing identified novel null variants in AGRN . First, whole-exome sequencing revealed the maternally inherited heterozygous variant c.952+1₉₅₂₊₃del in AGRN in fetuses. Split-read analysis of the exome led to the identification of the paternally inherited second variant, a heterozygous deletion of 41.33 kb, encompassing exons 1 and 2 of AGRN. This study highlights the importance of incorporating split-read analysis in clinical practice and emphasizes the association of null variants in AGRN with the FADS. To the best of our knowledge, this is the second report explaining FADS and null variants in AGRN . Show less

This study was aimed at assessing the diagnostic utility of whole genome sequence analysis in a well-characterised research cohort of individuals referred with a clinical suspicion of Cornelia de Lange syndrome (CdLS) in whom prior genetic testing had not identified a causative variant. Short-read whole genome sequencing was performed on 195 individuals from 105 families, 108 of whom were affected. 100/108 of the affected individuals had prior relevant genetic testing, with no pathogenic variant being identified. The study group comprised 42 trios in which both parental samples were available for testing (42 affected individuals and 126 unaffected parents), 61 singletons (unrelated affected individuals), and two families with more than one affected individual. The results showed that 32 unrelated probands from 105 families (30.5%) had likely causative coding region-disrupting variants. Four loci were identified in > 1 proband: Show less

Dyggve-Melchior-Clausen dysplasia (DMC) and Smith-McCort dysplasia (SMC types 1 and 2) are rare spondyloepimetaphyseal dysplasias with identical radiological findings. The presence of intellectual disability in DMC and normal intellect in SMC differentiates the two. DMC and SMC1 are allelic and caused by homozygous or compound heterozygous variants in Detailed clinical phenotyping and skeletal radiography followed by molecular testing were performed in all affected individuals. Next-generation sequencing and Sanger sequencing were used to confirm 24 affected individuals from seven centres are described. 18 had DMC and 6 had SMC2. Parental consanguinity was present in 15 of 19 (79%). Height <3 SD and gait abnormalities were seen in 20 and 14 individuals, respectively. The characteristic radiological findings of lacy iliac crests and double-humped vertebral bodies were seen in 96% and 88% of the affected. Radiological findings became attenuated with age. 23 individuals harboured biallelic variants in either This large cohort from India contributes to the increasing knowledge of clinical and molecular findings in these rare 'Golgipathies'. Show less

Fetal akinesia deformation sequence (FADS) is a clinically and genetically heterogeneous condition. Pathogenic variants in DOK7 are known to cause myasthenic syndrome, congenital, 10 (MIM#254300) and, rarely (reported in a single family) lethal FADS. Herein, we describe a biallelic variant c.1263dupC in DOK7, known to cause congenital myasthenic syndrome 10, causing lethal FADS in a consanguineous family. The present report illustrates wide phenotypic variability caused by biallelic pathogenic variants in DOK7. We also describe the second family with FADS due to pathogenic variants in DOK7. Show less

Glycogen storage disease IV (GSD IV), caused by a defect in GBE1, is a clinically heterogeneous disorder. A classical hepatic form and a neuromuscular form have been described. The severe neuromuscular form presents as a fetal akinesia deformation sequence or a congenital subtype. We ascertained three unrelated families with fetuses/neonates who presented with fetal akinesia deformation sequence to our clinic for genetic counseling. We performed a detailed clinical evaluation, exome sequencing, and histopathology examination of two fetuses and two neonates from three unrelated families presenting with these perinatally lethal neuromuscular forms of GSD IV. Exome sequencing in the affected fetuses/neonates identified four novel pathogenic variants (c.1459G>T, c.144-1G>A, c.1680C>G, and c.1843G>C) in GBE1 (NM₀₀₀₁₅₈₎. Histopathology examination of tissues from the affected fetuses/neonate was consistent with the diagnosis. Here, we add three more families with the severe perinatally lethal neuromuscular forms of GSD IV to the GBE1 mutation spectrum. Show less

Smith-McCort dysplasia (SMC OMIM 615222) and Dyggve-Melchior-Clausen dysplasia (DMC OMIM 223800) are allelic skeletal dysplasias caused by homozygous or compound heterozygous mutations in DYM (OMIM 607461). Both disorders share the same skeletal phenotypes characterized by spondylo-epi-metaphyseal dysplasia with distinctive lacy ilia. The difference rests on the presence or absence of intellectual disability, that is, intellectual disability in DMC and normal cognition in SMC. However, genetic heterogeneity was suspected in SMC. Recently, RAB33B (OMIM 605950) has been identified as the second gene for SMC. Nevertheless, only two affected families have been reported so far. Here we present three SMC patients with four novel pathogenic variants in RAB33B, including homozygosity for c.211C>T (p.R71*), homozygosity for c.365T>C (p.F122S), and compound heterozygosity for c.48delCGGGGCAG (p.G17Vfs*58) and c.490C>T (p.Q164*). We also summarize the clinical, radiological, and mutation profile of RAB33B after literature mining. This report ascertains the pathogenic relationship between RAB33B and SMC. © 2017 Wiley Periodicals, Inc. Show less

We report on two unrelated fetuses born to nonconsanguineous couples with fetal akinesia deformation sequence (FADS). The fetuses shared facial features, micrognathia, fetal finger pads, bulbous digital tips, pterygia, clubfeet, ventriculomegaly, and cerebellar anomalies. Both had loss/absence of Purkinje cells in cerebellum. The first family had a similarly affected previous pregnancy suggesting an autosomal recessive inheritance. The second fetus, in addition to the findings in the first, had cleft palate and defective lobulation of lungs. These fetuses appear to have the Pena-Shokeir phenotype (PSP) or FADS. These two cases seem to define a newly recognizable subtype of FADS with bulbous digital tips, prominent digit pads and cerebellar anomalies, and highlight the phenotypic diversity of syndromes with multiple congenital contractures manifesting in utero. Show less