Article

Mutational spectrum of steroid 21-hydroxylase and the genotype-phenotype association in Middle European patients with congenital adrenal hyperplasia.

Institute of Biochemistry, Faculty of Medicine, University of Ljubljana, Ljubljana, Slovenia.
European Journal of Endocrinology (impact factor: 3.42). 08/2005; 153(1):99-106. DOI:10.1530/eje.1.01944 pp.99-106
Source: PubMed

ABSTRACT To analyze the mutational spectrum of steroid 21-hydroxylase (CYP21) and the genotype- phenotype correlation in patients with congenital adrenal hyperplasia (CAH) registered in the Middle European Society for Pediatric Endocrinology CAH database, and to design a reliable and rational approach for CYP21 mutation detection in Middle European populations.
Molecular analysis of the CYP21 gene was performed in 432 CAH patients and 298 family members. Low-resolution genotyping was performed to detect the eight most common point mutations. High-resolution genotyping, including Southern blotting and sequencing was performed to detect CYP21 gene deletions, conversions, point mutations or other sequence changes.
CYP21 gene deletion and In2 and Ile172Asn mutation accounted for 72.7% of the affected alleles in the whole study group. A good genotype-phenotype correlation was observed, with the exception of Ile172Asn and Pro30Leu mutations. In 37% of patients low resolution genotyping could not identify the causative mutation or distinguish homozygosity from hemizygosity. Using high-resolution genotyping, the causative mutations could be identified in 341 out of 348 analyzed patients. A novel mutation Gln315Stop was found in one simple virilising CAH (SV-CAH) patient from Austria. In the remaining seven patients polymorphisms were identified as the leading sequence alteration. The presence of elevated basal and ACTH-stimulated 17-hydroxyprogesterone, premature pubarche, advanced bone age and clitoral hypertrophy directly implicated Asn493Ser polymorphism in the manifestation of nonclassical- (NC) and even SV-CAH.
By genotyping for the most common point mutations, CYP21 gene deletion/conversion and the 8 bp deletion in exon 3, it should be possible to identify the mutation in 94-99% of the diseased alleles in any investigated Middle European population. In patients with a mild form of the disease and no detectable mutation CYP21 gene polymorphisms should be considered as a plausible disease-causing mutation.

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Keywords

348 analyzed patients
 
432 CAH patients
 
8 bp deletion
 
causative mutation
 
causative mutations
 
common point mutations
 
congenital adrenal hyperplasia
 
CYP21 gene deletion
 
CYP21 gene deletion/conversion
 
detectable mutation CYP21 gene polymorphisms
 
exon 3
 
Ile172Asn mutation
 
Molecular analysis
 
plausible disease-causing mutation
 
point mutations
 
premature pubarche
 
Pro30Leu mutations
 
remaining seven patients polymorphisms
 
simple virilising CAH
 
whole study group