3-hydroxyisobutyric aciduria: phenotypic heterogeneity within a single family

3-hydrolyisobutyric aciduria is a rare biochemical finding associated with a variable clinical phenotype in the literature. We report two siblings exc reting abnormal levels of this matbolite from a consanguineous family who m anifested distinct phenotypic variation. We speculate as to whether this bi ochemical anomaly may simply be an incidental finding and suggest that pre- natal counselling on the basis of metabolite identification may be unwarran ted. Clin Dysmorphol 10: 189-191 (C) 2001 Lippincott Williams & Wilkins.