3-HYDROXYISOBUTYRIC ACIDURIA WITH A MILD CLINICAL COURSE

At least 7 patients have been identified with increased excretion of 3 -hydroxyisobutyric acid (3HiB), an intermediate of the catabolic pathw ays of valine and of the pyrimidines. Clinical heterogeneity seems to be common among the few patients reported, ranging from uneventful cli nical course in one to congenital malformations (dysmorphic features, brain dysgenesis, microcephaly, clinodactyly) associated with failure to thrive, hypotonia or infantile spasms (Gibson et al 1993). Two of t hese patients with suspected combined malonic, methylmalonic and ethyl malonic semialdehyde dehydrogenase deficiencies have been described: o ne with an uneventful clinical course (Pollitt et al 1985), the other with failure to thrive, recurrent vomiting and dysmorphic features (Gi bson et al 1993). We present a new patient with 3HiBuria with up to no w a mild clinical course.