Molybdenum Cofactor Deficiency Masquerading as Hypoxic-Ischemic Encephalopathy Sequelae

A bstract Molybdenum cofactor deficiency (MoCD) is an inborn error of metabolism characterized by refractory seizures, global developmental delay with psychomotor retardation, and lens dislocation. It may mimic hypoxic-ischemic encephalopathy (HIE) in the neonatal period with seizures and encephalopathy. Later, spastic quadriparesis, microcephaly, and recurrent seizures with imaging features of multi-cystic encephalomalacia masquerading as HIE sequelae. Knowledge about this condition is essential to confirm the diagnosis in the index case and for genetic counseling. A 5-month-old baby presented with recurrent flexor spasms and developmental delay. Examination revealed spastic quadriparesis, microcephaly, and visual difficulty. The child had seizures since the second postnatal day and was on three antiseizure medications. A previous sibling had a similar illness and died at 10 months of age. Magnetic resonance imaging of the brain showed multi-cystic encephalomalacia. Serum calcium, magnesium, lactate, and ammonia were normal. Tandem mass spectrometry was negative. Serum uric acid was low, and urine sulfites were elevated suggestive of MoCD. Genetic testing confirmed the diagnosis. The child was treated with oral steroids for epileptic spasms, antiseizure medications in addition to physiotherapy, occupational therapy and speech therapy. A high index of suspicion is necessary to identify MoCD which may mimic HIE.