A rare neurometabolic disorder with features of seizures, progressive encephalopathy and lens dislocation. The prevalence is unknown but is very rare. Symptoms usually occur within the first week after birth with feeding difficulties, vomiting and seizures which are difficult to control. The majority of patients exhibit facial dysmorphism. The course is progressive, with spasticity, severe intellectual deficit, and microcephaly seen in survivors. Lens dislocation usually occurs late in infancy but has been observed as early as two months of age. A late onset form with a milder phenotype has also been described. Caused by a mutation in the SUOX gene (12q13.13). The disease follows an autosomal recessive pattern of inheritance.