Congenital adrenal hyperplasia (CAH) is a group of autosomal recessive disorders that result in impaired hormone production from the adrenal glands. The most common form of CAH is caused by a deficiency of the enzyme 21-hydroxylase (21-OHD) which accounts for over 90% of people with CAH (White & Speiser 2000 PMID: 10857554).
This condition is extremely variable and depends on the level of impairment of production of cortisol and aldosterone. Classical CAH, due to severe enzyme deficiency, can be divided into two phenotypes: salt wasting (SW) and simple virilising (SV). SW is the most severe form of CAH and can be a life-threatening condition if not recognised and treated. In SV CAH, virilisation occurs because of increased production of male sex hormones by the adrenal glands. The non-classical form of CAH is due to mild enzyme deficiency and patients may present with mild symptoms of androgen excess.
CAH is caused by disease-causing variants in the CYP21A2 gene. There is some correlation between CYP21A2 genotype and phenotype. Our assay will detect at least 90% of all CYP21A2 variants.
For diagnostic referrals please also send samples from parents, where possible, to aid the interpretation of any variants identified.
NHSE test directory code: R180 Congenital adrenal hyperplasia. Testing criteria can be found on this webpage: https://www.england.nhs.uk/publication/national-genomic-test-directories/.
The laboratory participates in the European Molecular Genetics Quality Network (EMQN) CAH scheme.