Neurodegeneration due to 3-hydroxyisobutyryl-CoA hydrolase deficiency is characterized by delayed motor development, hypotonia and progressive neurodegeneration. To date, it has been described in four boys. The syndrome is caused by mutations affecting the two alleles of the HIBCH gene, encoding 3-hydroxyisobutyryl-CoA hydrolase. The mode of transmission has not yet been established. The disease is Monarch Disease Ontology term MONDO_0009603 (3-hydroxyisobutyryl-CoA hydrolase deficiency). Also known as: 3-hydroxyisobutryl-CoA hydrolase deficiency, HIBCH deficiency, methacrylic aciduria, neurodegeneration due to 3-hydroxyisobutyryl-CoA hydrolase deficiency.