HADH

At least three mutations in the HADH gene have been found to cause 3-hydroxyacyl-CoA dehydrogenase deficiency. These mutations change single protein building blocks (amino acids) used to make the 3-hydroxyacyl-CoA dehydrogenase enzyme. These changes probably alter the 3-dimensional shape of the enzyme, which impairs its normal function.

With a shortage (deficiency) of functional 3-hydroxyacyl-CoA dehydrogenase, medium-chain and short-chain fatty acids are not metabolized properly. As a result, these fatty acids are not converted to energy, which can lead to signs and symptoms of 3-hydroxyacyl-CoA dehydrogenase deficiency such as lack of energy (lethargy) and low blood glucose (hypoglycemia). Medium-chain and short-chain fatty acids that are not broken down can build up in tissues and damage the liver, heart, and muscles, causing serious complications.

MedlinePlus Genetics provides information about Congenital hyperinsulinism

Mutations in the HADH gene have been reported in a small number of people with familial hyperinsulinism. This disorder is characterized by abnormally high levels of insulin (hyperinsulinism) and unusually low blood glucose (hypoglycemia).

Researchers have identified at least five HADH gene mutations that cause familial hyperinsulinism. These mutations severely reduce 3-hydroxyacyl-CoA dehydrogenase activity, either by impairing the enzyme's function or by decreasing the amount of this enzyme in cells. Researchers believe that inadequate 3-hydroxyacyl-CoA dehydrogenase activity in the pancreas leads to excessive insulin secretion and hypoglycemia in people with familial hyperinsulinism. It is unclear why the HADH gene mutations that cause familial hyperinsulinism seem to affect only the pancreas.