2-Methylbutyrylglycinuria, also known as Short/branched chain acyl-CoA dehydrogenase (SBCAD) deficiency) is an autosomal recessive disorder caused by pathogenic variants in the gene ACADSB. Most individuals with this condition are clinically asymptomatic and show normal development. A small percentage of individuals present with symptoms shortly after birth or in early childhood. Symptoms include delayed development, neonatal crisis, muscular hypotonia, muscular atrophy, intellectual disability, seizures, and autism. This disorder has been commonly reported among the Hmong populations in Southeast Asia and individuals of Hmong descent. However, these individuals may be asymptomatic. No clear genotype-phenotype correlation has been established. Life expectancy of the affected individuals is normal.
For information about carrier frequency and residual risk, please see the residual risk table.