This gene encodes a homotetrameric mitochondrial flavoprotein and is a member of the acyl-CoA dehydrogenase family. Members of this family catalyze the first step of fatty acid beta-oxidation, forming a C2-C3 trans-double bond in a FAD-dependent reaction. As beta-oxidation cycles through its four steps, each member of the acyl-CoA dehydrogenase family works at an optimum fatty acid chain-length. This enzyme has its optimum length between C6- and C12-acylCoA. In mice, deficiency of this gene can cause neonatal mortality as well as fasting and cold intolerance. This gene has multiple, intronless pseudogenes. [provided by RefSeq, Nov 2012]