This is an abbreviated version, for detailed information about 3-hydroxy-2-methylbutyryl-CoA dehydrogenase, go to the full flat file.
17beta-HSD10, 2-methyl-3-hydroxy-butyryl CoA dehydrogenase, 2-methyl-3-hydroxybutyryl coenzyme A dehydrogenase, 2-methyl-3-hydroxybutyryl-CoA dehydrogenase, 3-hydroxyacyl-CoA dehydrogenase type II, dehydrogenase, 2-methyl-3-hydroxybutyryl coenzyme A, HSD10, MHBD, short-chain L-3-hydroxy-2-methylacyl-CoA dehydrogenase
MHBD deficiency is a X-linked inborn error in the metabolism of isoleucine. Impairment of energy metabolism seems to play a role in the pathogenesis of MHBD deficiency. Males are more severely affected than females by MHBD deficiency. Male patients with MHBD deficiency before 10 months of age show neurodegeneration, while female carriers show a variety of symptoms (borderline learning difficulties to psychomotor and speech delay)
mutation p.D86G c.257A>G in exon 3 was diagnosed in one child with a very severe neonatal presentation, absent neurological development and death from progressive hypertrophic cardiomyopathy at the age of 7 months. MHBD activity in fibroblasts was only partially reduced to approximately 30% of normal. Mutation p.Q165H c.495A>C in exon 5 was diagnosed in a boy who presented with pre- and postnatal failure to thrive but normal cognitive and motor development. Neurological examination in this boy and two affected relatives has been entirely normal up to the present age of 8 years. There is no measurable MHBD activity in fibroblasts, molecular studies identified hemizygosity for the mutation. There is no correlation between enzyme activity and clinical presentation. HSD10 is essential for structural and functional integrity of mitochondria independently of its enzymatic activity. Impairment of this function in neural cells causes apoptotic cell death whilst the enzymatic activity of HSD10 is not required for cell survival
mutant loses most or all catalytic functions, and the males with this mutation have a severe clinical phenotype. The mutation eliminates several hydrogen bonds and reduces the van der Waals interaction between HSD10 subunits. The resulting disruption of protein structure impairs some if not all of the catalytic and non-enzymatic functions of HSD10. Eight patients with the R130C mutation show an average 2-methyl-3-hydroxybutyryl-CoA dehydrogenase activity of only 6% of the normal control level