Report of three patients, including monozygotic twins and review of clinical and mutation profiles

Genetic and allelic heterogeneity in 248 Indians with skeletal dysplasia

Skeletal dysplasias are a clinically and genetically heterogeneous group of rare disorders. Studies from large cohorts are essential to provide insights into the disease epidemiology, phenotypic spectrum, and mutational profiles. Here we enumerate additional 248 Indians from 197 families with a skeletal dysplasia, following a similar study earlier. We achieved a clinical-molecular diagnosis in 145 families by targeted analysis in 37 and next generation sequencing (exomes and genomes) in 108 families that resulted in a diagnostic yield of 73.6% (145 of 197 families). We identified 149 causal variants, of which 85 were novel, across 73 genes. Eighty-one distinct monogenic forms of skeletal dysplasia were observed with a high proportion of autosomal recessive skeletal dysplasias (60%, 84 families). We observed consanguinity in 35% of the families. Lysosomal storage diseases with skeletal involvement, FGFR3-related skeletal dysplasia and disorders of bone mineralisation were most frequent in this cohort. We expand the phenotypic and genotypic spectrum of rarely reported conditions (RAB33B, TRIP11, NEPRO, RPL13, COL27A1, PTHR1, EXOC6B, PRKACA, FUZ and RSPRY1) and noted novel gene-disease relationships for PISD, BNIP1, TONSL, CCN2 and SCUBE3 related skeletal dysplasia. We successfully implemented genomic testing for skeletal dysplasia in clinical and research settings. Our study provides valuable information on the spectrum of skeletal dysplasia and disease-causing variants for Asian Indians.

Identification of novel genes regulating the development of the palate

The International Mouse Phenotyping Consortium (IMPC) has generated thousands of knockout mouse lines, many of which exhibit embryonic or perinatal lethality. Using micro-computed tomography (micro-CT), the IMPC has created and publicly released 3D image datasets of embryos from these lethal and subviable lines. In this study, we leveraged this dataset to screen homozygous null mutants for anomalies in secondary palate development. We analyzed optical sections from 2,987 embryos at embryonic days E15.5 and E18.5, representing 484 homozygous mutant lines. Our analysis identified 45 novel genes implicated in palatogenesis. Gene set enrichment analysis highlighted biological processes and pathways relevant to palate development and uncovered 18 genes jointly regulating the development of the eye and the palate. These findings present a valuable resource for further research, offer novel insights into the molecular mechanisms underlying palatogenesis, and provide important context for understanding the etiology of rare human congenital disorders involving simultaneous malformations of the palate and other organs, including the eyes, ears, kidneys, and lungs.