Mutational spectrum of congenital adrenal hyperplasia in Slovenian patients: a novel Ala15Thr mutation and Pro30Leu within a larger gene conversion associated with a severe form of the disease

Eur J Endocrinol. 2003 Aug;149(2):137-44. doi: 10.1530/eje.0.1490137.

Abstract

Objective: To analyse the mutational spectrum, the associated haplotypes and the genotype-phenotype correlation, and to design a reliable and rational approach for CYP21 mutation detection in Slovenian congenital adrenal hyperplasia (CAH) patients.

Design: Molecular analysis of the CYP21 gene was performed in 36 CAH patients and 79 family members.

Methods: Southern blotting, sequence-specific PCR amplification (PCR-SSP), sequence-specific oligonucleotide hybridisation (PCR-SSO) and sequencing were used to detect CYP21 gene deletions, conversions and point mutations.

Results: CYP21 gene deletion was the most frequent mutation (36.4%). Large gene conversions detectable only by Southern blotting represented 12.1%, and gene conversions involving the promoter region represented 7.6% of the mutated alleles. The most frequent point mutations were: intron 2 splice mutation 16.7%, Ile172Asn mutation 7.6%, Gln318Stop 7.5% and Pro30Leu 12.2% of alleles. A correlation between the genotype and the clinical phenotype similar to those described for large populations was observed. The finding of Pro30Leu mutation linked to a gene conversion could explain the simple virilising (SV) phenotype in compound heterozygotes for the Pro30Leu and a severe mutation. In two siblings with a salt wasting form of CAH (SW-CAH), a novel mutation Ala15Thr was found on the allele characterised by Pro30Leu mutation and gene conversion involving the promoter region.

Conclusions: Our genotyping approach allowed reliable diagnosis of CAH in the Slovenian population. The high frequency of CYP21 gene aberrations on Pro30Leu positive alleles justified systematic searching for a gene conversion in the promoter region using the PCR-SSP reaction.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Adrenal Hyperplasia, Congenital / genetics*
  • Adrenal Hyperplasia, Congenital / physiopathology
  • Alleles
  • Amino Acid Substitution
  • Blotting, Southern
  • Child
  • Child, Preschool
  • DNA Mutational Analysis
  • Female
  • Gene Conversion / genetics
  • Gene Deletion
  • Genotype
  • Haplotypes
  • Humans
  • Infant
  • Infant, Newborn
  • Male
  • Oligonucleotides / genetics
  • Phenotype
  • Point Mutation
  • Reverse Transcriptase Polymerase Chain Reaction
  • Slovenia
  • Steroid 21-Hydroxylase / genetics

Substances

  • Oligonucleotides
  • Steroid 21-Hydroxylase