Novel Imaging Finding and Novel Mutation in an Infant with Molybdenum Cofactor Deficiency, a Mimicker of Hypoxic-Ischaemic Encephalopathy

Molybdenum cofactor deficiency is a rare metabolic disorder manifesting with early onset seizures, developmental delay, microcephaly, and spasticity. In this report, we describe a three-month-old infant with neonatal onset, poorly controlled seizures, developmental delay, microcephaly, spastic quadriparesis and visual insufficiency. Magnetic resonance imaging of brain had shown cystic encephalomalacia involving bilateral parieto-occipital lobe and elevated lactate in magnetic resonance spectroscopy. Restricted diffusion noted along the corticospinal tract in our case is a novel imaging finding in patients with molybdenum cofactor deficiency. Low serum uric acid and elevated urine sulfite excretion were observed. A novel homozygous mutation was detected in exon 4 of molybdenum cofactor synthesis 2 (MOCS2) gene. Early infantile or neonatal onset seizures, developmental delay, microcephaly and cystic encephalomalacia in neuroimaging mimicking hypoxic-ischaemic encephalopathy should raise the suspect for molybdenum cofactor deficiency. Screening of all neonates for urinary sulfite metabolites would help in early diagnosis and management. Early diagnosis and treatment with cyclic pyranopterin monophosphate could arrest the progression of molybdenum cofactor deficiency type A. More research is needed to explore further treatment options in this otherwise lethal disorder.