Frequency of CYP21 gene mutations in Czech patients with steroid 21-hydroxylase deficiency and statistical comparison with other populations.

OBJECTIVE To undertake mutational analysis in patients with different forms of steroid 21-hydroxylase deficiency. SUBJECTS AND METHODS CYP21 gene molecular analysis was performed in 76 Czech patients diagnosed with steroid 21-hydroxylase deficiency. Eight of the most common point mutations (intron 2 splice, P30L, 8bp deletion in exon 3, I172N, V281L, Q318X, R356W, and P453S) were analyzed using an amplification-created restriction site method, and 5 additional mutations (intron 7 splice, F307insT, cluster in exon 6, R484P, and R484X) were analyzed using dot-blot hybridization with 5'-biotin-labeled oligonucleotides. Deletions and conversions were screened using a sequence-specific oligonucleotide hybridization method. Comparison of common mutation frequencies in CYP21 reported for different regions, both within Europe and worldwide (North and South America, Asia, and North Africa), was undertaken and the significance of the differences was determined by statistical analysis (Fisher's F test, Student's t test, paired t test, and confidence intervals) using a value of p < 0.05. RESULTS The most frequent genetic defect found in this group of Czech patients was intron 2 splice mutation (46.7%). Comparison of mutation frequencies between Czech and other European populations showed that the Czech patients had a lower frequency of deletions/large gene conversions, R356W, and cluster mutations in exon 6, together with a higher frequency of intron 2 splice mutation, 8-bp deletion and F307insT compared with other populations. CONCLUSION A high prevalence of P30L mutations, mostly associated with nonclassical forms of congenital adrenal hyperplasia, was found in Czech patients with classic simple virilizing forms of steroid 21-hydroxylase deficiency.