Medical College of Wisconsin
CTSICores SearchResearch InformaticsREDCap

Exon 7 Ncol restriction site within CYP21B (steroid 21-hydroxylase) is a normal polymorphism. Mol Endocrinol 1990 Sep;4(9):1354-62



Pubmed ID




Scopus ID

2-s2.0-0025066445   13 Citations


A point mutation within exon 7 producing an amino acid coding change and a recognition site for the endonuclease Ncol has been reported in the HLA-Bw47-linked CYP21A pseudogene and some mutant CYP21B (steroid 21-hydroxylase) genes of patients with congenital adrenal hyperplasia (CAH). Whether this mutation is deleterious was not demonstrated. We analyzed DNA from various subjects for the presence of the exon 7 Ncol site: group 1, 10 normal subjects; group 2, 11 patients with salt-losing CAH; and group 3, 18 members of an Amish pedigree in which 10 expressed HLA-Bw47 not linked to CAH. Southern blots of Ncol-digested genomic DNA which were hybridized with CYP21 cDNA showed that four subjects of group 1 had a heterozygous Ncol pattern. In group 2, seven patients had the Ncol site; two of them were homozygous for the site and had deletions of both CYP21B genes. The other five were heterozygous for the Ncol site, which was linked to a CYP21B deletion and a HLA-Bw47 haplotype. In group 3, no one exhibited the exon 7 Ncol site. To map the Ncol sites to CYP21A or CYP21B in the normal subjects, DNA from the four Ncol heterozygous subjects was double digested with Ncol and Mbol and hybridized with CYP21 cDNA. Ncol-Mbol fragments unique to CYP21A were identified in all four, but the smaller CYP21B-specific fragments were not detected. Their genomic DNA in the region of exon 7 (bases +1167 to +2058) was then amplified, cloned, and sequenced.(ABSTRACT TRUNCATED AT 250 WORDS)

Author List

Donohoue PA, Sandrini Neto R, Collins MM, Migeon CJ


Patricia A. Donohoue MD Chief, Professor in the Pediatrics department at Medical College of Wisconsin

MESH terms used to index this publication - Major topics in bold

Adrenal Hyperplasia, Congenital
Adrenocorticotropic Hormone
Base Sequence
Chromosome Deletion
Deoxyribonucleases, Type II Site-Specific
HLA-B Antigens
Molecular Sequence Data
Polymerase Chain Reaction
Polymorphism, Restriction Fragment Length
Restriction Mapping
Steroid 21-Hydroxylase