Microencephaly in macrocephaly: Rare report of two siblings with glutaric aciduria type 1

Glutaric aciduria type 1 is an autosomal recessive disorder caused by mutations in GCDH gene on chromosome 19 leading to the deficiency of glutaryl-CoA dehydrogenase which causes an abnormal metabolism of lysine, hydroxylysine and tryptophan with resultant accumulation of glutaric acid and 3-hydroxy glutaric acid. Usual presentations include macrocephaly with recurrent dystonic episodes, along with developmental regression. The diagnosis is based on characteristic magnetic resonance imaging finding of widening of sylvian fissures and urinary tandem mass spectroscopic analysis of excess glutarylcarnitine and hydroxyglutaric acid. Management includes lysine-free diet and carnitine supplementation.