A defect within the CYP21B gene causes a disturbance of the development of the enzyme, which leads to congenital adrenal hyperplasia due to 21-hydroxylase deficiency. A related pseudogene is located near this gene; gene conversion events involving the functional gene and the pseudogene are thought account for many cases of steroid 21-hydroxylase deficiency.
^ Entrez Gene: CYP21A2 cytochrome P450, family 21, subfamily A, polypeptide 2.
White PC, Tusie-Luna MT, New MI, Speiser PW (1994). "Mutations in steroid 21-hydroxylase (CYP21).". Hum. Mutat.3 (4): 373-8. doi:10.1002/humu.1380030408. PMID 8081391.
Helmberg A (1993). "Twin genes and endocrine disease: CYP21 and CYP11B genes.". Acta Endocrinol.129 (2): 97-108. PMID 8372604.
de-Araujo M, Sanches MR, Suzuki LA, et al. (1996). "Molecular analysis of CYP21 and C4 genes in Brazilian families with the classical form of steroid 21-hydroxylase deficiency.". Braz. J. Med. Biol. Res.29 (1): 1-13. PMID 8731325.
Yu CY (1999). "Molecular genetics of the human MHC complement gene cluster.". Exp. Clin. Immunogenet.15 (4): 213-30. PMID 10072631.
Forest MG, Tardy V, Nicolino M, et al. (2005). "21-Hydroxylase deficiency: an exemplary model of the contribution of molecular biology in the understanding and management of the disease.". Ann. Endocrinol. (Paris)66 (3): 225-32. PMID 15988383.