A rare inherited genetic condition where the body is unable to convert certain fats to energy i.e. there is not enough of a certain enzyme (3-hydroxyacyl-coenzyme A dehydrogenase) which is needed to metabolize a type of fat called long-chain fatty acids. The build-up of these fatty acids in the body causes damage. See also Long-chain 3-hydroxyacyl-coenzyme A dehydrogenase deficiency