Prenatal brain disruption in isolated sulfite oxidase deficiency

Isolated sulfite oxidase deficiency (ISOD) is a very rare autosomal recessive inherited neurometabolic disease. The most striking postnatal neuroimaging finding is multicystic encephalomalacia, which occurs rapidly within days to weeks after birth and mimics severe hypoxic-ischemic encephalopathy. The aim of this study was to describe the prenatal neuroimaging features in a neonate and a fetus diagnosed with ISOD.

We report an 11-day-old female neonate who presented with feeding difficulties, decreased activity, neonatal seizures, and movement disorders within a few days after birth. Brain MRI at 9 days of age showed cystic lesions over the left frontal and temporal areas, diffuse and evident T2 high signal intensity of bilateral cerebral cortex, and increased T2 signal intensity of the globus pallidi. A pronounced low level of plasma cysteine and normal level of plasma uric acid were noted. Mutation analysis of SUOX revealed homozygous c.1200C > G mutations, resulting in an amino acid substitution of tyrosine to a stop codon (Y400X). The diagnosis of ISOD was made. The brain MRI of a prenatally diagnosed ISOD fetus of the second pregnancy of the mother of the index case showed poor gyration and differentiation of cortical layers without formation of cystic lesions at gestational age 21 weeks.

Cystic brain destruction might occur prenatally and neurodevelopment of gyration and differentiation of the cortical layers in the developing brain could be affected by sulfite accumulation early during the second trimester in ISOD patients. This is the first description of the prenatal neurodevelopment of brain disruption in ISOD.