Resolution of subependymal cysts in neonatal holocarboxylase synthetase deficiency

Abstract

Holocarboxylase synthetase deficiency is typically a biotin responsive disorder that presents with lactic acidosis, tachypnea, temperature instability, and shock in neonates. The primary defect in cases studied to date appears to be the decreased affinity of HCS for its substrate, biotin. Supplemental biotin can provide sufficient substrate to increase HCS enzymatic function and thereby permit biotinglation of the four carboxylase apoenzymes. We report an infant with HCS deficiencs who presented with lactic acidosis, shock, and hypertonia. Subependymal cysts were identified on cranial ultrasound and subsequently confirmed by MRI. Six months following biotin supplementation, she is developmentally normal and MRI of the brain shows complete resolution of the cysts.