MedGen

Congenital hyperinsulinism is a condition that causes individuals to have abnormally high levels of insulin. Insulin is a hormone that helps control levels of blood glucose, also called blood sugar. People with this condition have frequent episodes of low blood glucose (hypoglycemia). In infants and young children, these episodes are characterized by a lack of energy (lethargy), irritability, or difficulty feeding. Repeated episodes of low blood glucose increase the risk for serious complications such as breathing difficulties, seizures, intellectual disability, vision loss, brain damage, and coma.

The severity of congenital hyperinsulinism varies widely among affected individuals, even among members of the same family. About 60 percent of infants with this condition experience a hypoglycemic episode within the first month of life. Other affected children develop hypoglycemia by early childhood. Unlike typical episodes of hypoglycemia, which occur most often after periods without food (fasting) or after exercising, episodes of hypoglycemia in people with congenital hyperinsulinism can also occur after eating. [from MedlinePlus Genetics]

3-hydroxyacyl-CoA dehydrogenase deficiency is an inherited condition that prevents the body from converting certain fats to energy, particularly during prolonged periods without food (fasting).

Initial signs and symptoms of this disorder typically occur during infancy or early childhood and can include poor appetite, vomiting, diarrhea, and lack of energy (lethargy). Affected individuals can also have muscle weakness (hypotonia), liver problems, low blood glucose (hypoglycemia), and abnormally high levels of insulin (hyperinsulinism). Insulin controls the amount of glucose that moves from the blood into cells for conversion to energy. Individuals with 3-hydroxyacyl-CoA dehydrogenase deficiency are also at risk for complications such as seizures, life-threatening heart and breathing problems, coma, and sudden death. This condition may explain some cases of sudden infant death syndrome (SIDS), which is defined as unexplained death in babies younger than 1 year.

Problems related to 3-hydroxyacyl-CoA dehydrogenase deficiency can be triggered by periods of fasting or by illnesses such as viral infections. This disorder is sometimes mistaken for Reye syndrome, a severe disorder that may develop in children while they appear to be recovering from viral infections such as chicken pox or flu. Most cases of Reye syndrome are associated with the use of aspirin during these viral infections. [from MedlinePlus Genetics]