Mutation screening in British 21-hydroxylase deficiency families and development of novel microsatellite based approaches to prenatal diagnosis
- aDepartment of Human Genetics, University of Newcastle upon Tyne, Ridley Building, Claremont Place, Newcastle upon Tyne NE1 7RU, UK, bDepartment of Medical Genetics, St Mary’s Hospital, Hathersage Road, Manchester M13 0JH, UK, cMRC Immunochemistry Unit, Department of Biochemistry, University of Oxford, South Parks Road, Oxford, UK
- Professor Strachan.
- Received 19 March 1998
- Revised 2 July 1998
Abstract
21-hydroxylase deficiency is a recessively inherited disorder of steroidogenesis, resulting from mutations in the CYP21 gene. This 3.5 kb gene and a highly related CYP21P pseudogene reside on tandemly duplicated 30 kb segments of DNA in the class III HLA region, and the great majority of pathogenic mutations result from sequence exchanges involving the duplicated units. We now describe a comprehensive survey of CYP21 mutations in the British population, encompassing a screen for 17 different mutations in a total of 284 disease chromosomes. The most common mutations were as follows: large scale deletions/conversions (45% of the affected chromosomes), the intron 2 splice mutation (30.3%), R357W (9.8%), and I172N (7.0%). Mutations were detected in over 92% of the chromosomes examined, suggesting that accurate DNA based diagnosis is possible in most cases using the described strategy. In order to extend highly accurate prenatal diagnosis to all families where samples are available from a previously affected child, we have developed a linkage analysis approach using novel, highly informative microsatellite markers from the class III HLA region.
