Congenital Adrenal Hyperplasia - The Molecular Genetics Of 11¦Â-hydroxylase Deficiency

Background and purpose: Congenital adrenal hyperplasia (CAH) is a group of autosomal recessive disorder. It is one of the commonest genetic endocrinological diseases. 11 β -hydroxylase deficiency accounts for 5-8% of CAH, which is encoded by a gene named CYP11B1. CYP11B1 locates inBand 22 on the long arm of chromosome 8, and consists of 9 exons. This study aimed to reveal the mutations and their origins of a patient who was diagnosed 11β -hydroxylase deficiency and her parents, and to define the molecular genetic basis of 11 β -hydroxylase deficiency. Subjects and method: 4 pairs of primers for PCR were design according to the sequence of CYP11B1 in gene database to amplify the 9 exons of the patients and her parents. And the PCR products were sequenced. The sequencing results were compared to CYP11B1 in normal subjects . Results: a homozygotic mis-sense mutation was found in CYP11B1 gene of the patient: the 339th codon of CYP11B1 was changed from GCC to GTC, and the corresponding points of her parents were both heterozygotic mutations as C and T. This resulted in a change the 339th amino acid of 11 β -hydroxylase changed from Ala to Val. And thus the primary structure of the protein was changed. Conclusion: the mutation A339V of CYP11B1 hasn't been reported so far. It suggests the 339th amino acid in the primary structure of 11 β -hydroxylase is essential to maintain the activity of this enzyme.