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The variants of\u00a0the <jats:italic>CBS<\/jats:italic>\u00a0gene remain unidentified in Indian children with this disorder. Based on the hallmark clinical features, family history, and\/or biochemical clues for classical homocystinuria, 16 children below the age of 18\u00a0years were evaluated by Sanger sequencing of the coding exons of\u00a0<jats:italic>CBS<\/jats:italic>\u00a0gene with flanking intronic regions. The common C677T variant of the <jats:italic>MTHFR<\/jats:italic>\u00a0gene was also screened by restriction fragment length polymorphism. Fifteen children were clinically suspected of having classical homocystinuria\u00a0and one asymptomatic child\u00a0with positive family history. Only seven children had biochemical features of classical homocystinuria. Sanger sequencing of the\u00a0<jats:italic>CBS<\/jats:italic>\u00a0gene confirmed 15 different pathogenic or likely pathogenic variants in 14\u00a0cases. Of these, seven variants were novel (three frameshift deletions, two nonsense, one missense, one splice site variant) and were predicted to be deleterious by Mutation Taster software. Seven cases were homozygous, another six were compound heterozygous, and one case was single heterozygous in the study. None of the three most frequent mutations reported worldwide viz., I278T, G307S, and IVS 11-2A&gt;C were found in our cohort. No variants were detected in the exons 2, 8, 12, and 14 as compared to reported literature. Eleven out of 15 variants were associated with the conserved catalytic domain of the CBS polypeptide. The\u00a0<jats:italic>MTHFR<\/jats:italic>\u00a0polymorphism C677T was observed in heterozygous state in six cases.\u00a0Our study reports the detailed genotype and seven novel variants in\u00a0the <jats:italic>CBS<\/jats:italic>\u00a0gene, causing classical homocystinuria in Indian children. The genetic analysis will help to offer accurate genetic counseling, prenatal diagnosis, and development of mutation-based novel therapeutic strategies.<\/jats:p>","DOI":"10.1038\/s41598-020-73475-5","type":"journal-article","created":{"date-parts":[[2020,10,14]],"date-time":"2020-10-14T10:04:52Z","timestamp":1602669892000},"update-policy":"https:\/\/doi.org\/10.1007\/springer_crossmark_policy","source":"Crossref","is-referenced-by-count":15,"title":["Seven novel genetic variants in a North Indian cohort with classical homocystinuria"],"prefix":"10.1038","volume":"10","author":[{"given":"Rajdeep","family":"Kaur","sequence":"first","affiliation":[],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Savita V.","family":"Attri","sequence":"additional","affiliation":[],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Arushi G.","family":"Saini","sequence":"additional","affiliation":[],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Naveen","family":"Sankhyan","sequence":"additional","affiliation":[],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Satwinder","family":"Singh","sequence":"additional","affiliation":[],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Mohammed","family":"Faruq","sequence":"additional","affiliation":[],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"V. 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