Background: AICA (5-aminoimidazole-4-carboxamide) ribosiduria is an inborn error in purine biosynthesis caused due to biallelic pathogenic variants in the 5-aminoimidazole-4-carboxamide ribonucleotide-formyltransferase/imp cyclohydrolase (ATIC) gene located on chromosome 2q35. ATIC codes for a bifunctional enzyme, AICAR transformylase and inosine monophosphate (IMP) cyclohydrolase, which catalyse the last two steps of de novo purine synthesis. This disorder has been previously reported in only 4 cases worldwide, and herein, we report the first from India.
Case report: The proband presented with global developmental delay, developmental hip dysplasia (DDH), acyanotic heart disease and nystagmoid eye movements. Whole exome sequencing (WES) identified compound heterozygous pathogenic variants in the ATIC. A novel splice site variant; c.1321-2A > G and a previously reported missense variant; c.1277A > G (p.Lys426Arg) were identified. Segregation analysis of parents showed the father to be a heterozygous carrier for the splice site variant and the mother, a heterozygous carrier for the missense variant.
Conclusion: This case of a rare genetic disorder of purine biosynthesis of ATIC deficiency is the first case reported from India. Early diagnosis lead to early interventional therapy and genetic counselling.
Keywords: 5-Aminoimidazole-4-carboxamide (AICA)-ribosiduria; 5-Aminoimidazole-4-carboxamide ribonucleotide-formyltransferase/imp cyclohydrolase (ATIC); Bratton-Marshall test; De novo purine synthesis; Indian; Inosine monophosphate (IMP) cyclohydrolase.
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