May be due to chromosomal rearrangements, mutation in individual genes, to environmental insult, or to combinations of factors. Some forms are attributable to environmental insult such as thalidomide ingested during pregnancy. This causes ambiguous external genitalia in females. A more severe form of the disease causes salt loss and can lead to death in newborn infants. The defect, caused by mutation of a recessive gene on chromosome 6p, can be treated in utero.
Some forms are attributable to environmental insults such as rubella and to maternal diabetes.
Multiple causes that may include genetic predisposition. The gene, on chromosome 7, causes production of excessive amounts of mucous, obstructing passageways causing chronic cough, recurrent pneumonia, emphysema, salt depletion and other symptoms. Affected infants often do not survive beyond childhood. Complications include blindness, kidney disease and degenerative changes in the blood vessels. Affected children have a risk of leukemia 15 times higher than the risk in unaffected children.