Glutaric Acidemia Type 1-Clinico-Molecular Profile and Novel Mutations in GCDH Gene in Indian Patients

Abstract

Glutaric acidemia I (GA I, #231670) is one of the treatable, autosomal recessively inherited metabolic disorders. Macrocephaly, acute encephalitis-like crises, dystonia and characteristic frontotemporal atrophy are the hallmarks of this disease. In this communication, we present the clinical, biochemical and molecular profile of seventeen GA I patients from 15 unrelated families from India and report seven novel mutations in GCDH gene (c.281G>A (p.Arg94Gln), c.401A>G (p.Asp134Gly), c.662T>C (p.Leu221Pro), c.881G>C (p.Arg294Pro), c.1173dupG (p.Asn392Glufs*5), c.1238A>G (p.Tyr413Cys) and c.1241A>C (p.Glu414Ala)). Out of these, c.662T>C (p.Leu221Pro) in exon 8 and c.281G>A (p.Arg94Gln) allele in exon 4 were low excretor alleles, whereas c.1241A>C (p.Glu414Ala), c.1173dupG and c.1207C>T (p.His403Tyr) in exon 11 were high excretor alleles. We conclude that c.1204C>T (p.Arg402Trp) is probably the most common mutant allele. Exons 11 and 8 are the hot spot regions of GCDH gene in Indian patients with GA I. An early diagnosis and timely intervention can improve the underlying prognosis. Molecular confirmation is helpful in providing genetic counselling and prenatal diagnosis in subsequent pregnancy.

Fig. 1

Mutation distribution across GCDH gene

Fig. 2

Cartoon representation of (a) crystal structure of wild-type human mitochondrial GCDH and model structure of mutants (b) Glu414Ala, (c) Tyr413Cys and (d) Arg294Pro. Side chain of important residues are shown (ball and stick in green for wild type and cyan for mutants), glutaryl-Co-A (ball and stick in magenta) and cofactor FAD (ball and stick in orange) and hydrogen-bonded interactions in black dotted lines. Glutaryl-CoA and FAD are shown partially