In a screen of 13 isobutyryl-CoA dehydrogenase deficiency patients identified through newborn screening, this variant (aka S149C) was found as a compound heterozygote (with M130T) in a male of European descent. The M130T variant was also found in 2 other patients. The cell line from this patient confirmed the biochemical phenotype. Normal controls were not reported, and the authors conclude that the condition is probably benign.
Found in a homozygously in a four-year-old girl in Portugal with feeding difficulties, systolic murmur, hypotonia, developmental delay, a systolic murmur and slight enlargement of the left ventricle. Metabolic investigation showed elevated isobutyryl/butyrylcarnatine, and mutation analysis of the ACAD8 gene showed homozygosity for the variant S171C (512C>G). This symptomatic case was diagnosed before the generalized implementation of newborn screening in Portugal.