title: DNA polymorphism unique for a complotype with deletion of HLA-linked C4B and 21-hydroxylase B genes causing congenital adrenal hyperplasia.
abstract: Defects in the enzyme steroid 21-hydroxylase (21-OH) result in congenital adrenal hyperplasia (CAH), a frequent disorder of steroid biosynthesis. The gene encoding the enzyme, 21-OHB, has been mapped adjacent to the complement component C4B gene in the human HLA gene complex. DNA-level analyses of patients with CAH have shown that the 21-OHB gene has often been deleted, but the detection of 21-OHB deletions in heterozygotes is often problematic because it is based on relative band intensities. We here report a DNA polymorphism in the C4A91 gene unique to one particular type of 21-OHB deletion occurring solely with a complement phenotype BfF C4A91 B null, shown earlier to be frequent in CAH patients. This marker makes direct detection of the 21-OHB deletion in heterozygotes possible.
mesh_terms: D000312:Adrenal Hyperplasia, Congenital / Q000235:genetics*; D002872:Chromosome Deletion; D003181:Complement C4 / Q000172:deficiency / Q000235:genetics*; D015935:Complement C4b; D008040:Genetic Linkage; D005819:Genetic Markers; D006680:HLA Antigens / Q000235:genetics; D006801:Humans; D008285:Major Histocompatibility Complex; D011110:Polymorphism, Genetic; D012150:Polymorphism, Restriction Fragment Length; D013255:Steroid 21-Hydroxylase / Q000235:genetics*; D013250:Steroid Hydroxylases / Q000235:genetics*
chemical_list: D003181:Complement C4; D005819:Genetic Markers; D006680:HLA Antigens; D015935:Complement C4b; D013250:Steroid Hydroxylases; D013255:Steroid 21-Hydroxylase