Chapter 16 - Acute Encephalopathy in Infants With Sulfite Oxidase Deficiency and Molybdenum Cofactor Deficiency

Abstract

Isolated sulfite oxidase deficiency (ISOD) and molybdenum cofactor deficiency (MoCoD) are ultraorphan recessive neurometabolic diseases. The diagnoses of ISOD and MoCoD rely on clinical manifestations and neuroimaging findings, together with biochemical tests and genetic analysis. Clinical manifestations may be nonspecific and include irritability, feeding problems, abnormal tone, and intractable seizures during the neonatal stage. These are followed by prominent dysmorphic features, movement disorders, spastic tetraplegia, persistent intractable seizures, ocular lens dislocation, and profound psychomotor impairment in infantile and early childhood stages. Brain neuroimaging findings show multicystic encephalomalacia and/or signal changes over the bilateral globus pallidi and/or thalami, which mimics severe hypoxic-ischemic encephalopathy. Plasma uric acid and metabolic survey, including plasma amino acids for the detection of decreased homocysteine, should be performed in any cases with intractable neonatal seizures to diagnose ISOD and MoCoD promptly. An accurate diagnosis is important for genetic counseling and, furthermore, potentially effective treatment for MoCoD type A to improve neurologic outcome.