title: CYP21 gene mutation analysis in 198 patients with 21-hydroxylase deficiency in The Netherlands: six novel mutations and a specific cluster of four mutations.
abstract: Congenital adrenal hyperplasia (CAH) due to 21-hydroxylase deficiency is one of the most common autosomal recessive disorders. The aim of this study was to assess the frequencies of CYP21 mutations and to study genotype-phenotype correlation in a large population of Dutch 21-hydroxylase deficient patients. From 198 patients with 21-hydroxylase deficiency, 370 unrelated alleles were studied. Gene deletion/conversion was present in 118 of the 370 alleles (31.9%). The most frequent point mutations were I2G (28.1%) and I172N (12.4%). Clustering of pseudogene-derived mutations in exons 7 and 8 (V281L-F306 + 1nt-Q318X-R356W) on a single allele was found in seven unrelated alleles (1.9%). This cluster had been reported before in two other Dutch patients and in two patients in a study from New York, but not in other series worldwide. Six novel mutations were found: 995-996insA, 1123delC, G291R, S301Y, Y376X, and R483Q. Genotype-phenotype correlation (in 87 well documented patients) showed that 28 of 29 (97%) patients with two null mutations and 23 of 24 (96%) patients with mutation I2G (homozygous or heterozygous with a null mutation) had classic salt wasting. Patients with mutation I172N (homozygous or heterozygous with a null or I2G mutation) had salt wasting (2 of 17, 12%), simple virilizing (10 of 17, 59%), or nonclassic CAH (5 of 17, 29%). All six patients with mutation P30L, V281L, or P453S (homozygous or compound heterozygous) had nonclassic CAH. The frequency of CYP21 mutations and the genotype-phenotype correlation in 21-hydroxylase deficient patients in The Netherlands show in general high concordance with previous reports from other Western European countries. However, a cluster of four pseudogene-derived point mutations on exons 7 and 8 on a single allele, observed in almost 2% of the unrelated alleles, seems to be particular for the Dutch population and six novel CYP21 gene mutations were found.
authors.affiliation: Department of Pediatric Endocrinology, University Medical Center Nijmegen, 6500 HB Nijmegen, The Netherlands.
authors.forename: Nike M M L
authors.initials: NM
authors.lastname: Stikkelbroeck
authors.forename: Lies H
authors.initials: LH
authors.lastname: Hoefsloot
authors.forename: Ilse J
authors.initials: IJ
authors.lastname: de Wijs
authors.forename: Barto J
authors.initials: BJ
authors.lastname: Otten
authors.forename: Ad R M M
authors.initials: AR
authors.lastname: Hermus
authors.forename: Erik A
authors.initials: EA
authors.lastname: Sistermans
mesh_terms: D000312:Adrenal Hyperplasia, Congenital / Q000201:enzymology / Q000235:genetics*; D000483:Alleles; D004252:DNA Mutational Analysis; D018076:DNA, Complementary / Q000096:biosynthesis / Q000235:genetics; D016368:Frameshift Mutation / Q000235:genetics; D005838:Genotype; D006801:Humans; D005810:Multigene Family / Q000235:genetics*; D009154:Mutation / Q000235:genetics*; D009426:Netherlands; D010375:Pedigree; D010641:Phenotype; D013255:Steroid 21-Hydroxylase / Q000096:biosynthesis / Q000235:genetics*
chemical_list: D018076:DNA, Complementary; D013255:Steroid 21-Hydroxylase