[Molecular characterization of mutations and phenotype/genotype correlation in Chinese patients with 21-hydroxylase...

To investigate characteristics of CYP21 mutations in Chinese patients with 21-hydroxylase deficiency (21-OHD) and the relationship between genotype and phenotype, a time saving, reliable molecular diagnosis method was developed. Eight patients with NC 21-OHD, 35 patients with classical ones and 34 normal controls were studied as followed: CYP21 gene was amplified into fragment 1 (exon1 --> exon3) and fragment 2 (exon3 --> exon10) through PCR with specific primers. The second round PCR was carried out using fragment 1 and 2 as template, and PCR products were digested by restrictive enzymes to analyze nine mutations, including Del, Exon3 Del8 bp, Q318X, R356W, Exon6Cluster, i2g, l172N, P30L and V281L. The most frequent mutation in 43 cases of Chinese 21-OHD was l172N (36.0%), followed by i2g (20.9%), Del (8.6%), P30L (7.0%), Q318X (7.0%), V281L (4.7%), R356W (2.3%), E6Cluster (2.3%) and Exon3 Del8 bp (1.2%). The most common CYP21 gene defect in salt wasting, simple virilizing and nonclassical form was Del (44.4%), l172N (44.2%) and P30L (37.5%) respectively. In addition, genotype was classified into three (severe, moderate and mild) groups according to the degree of 21-hydroxylase enzymatic compromise caused by the mutation. Age of first visit, basal 17-OHP, composition of disease subtype were significantly different among the three groups, P < 0.05. In conclusion, the most common mutations in Chinese 21-OHD were l172N, i2g and Del. The genotype of Chinese 21-OHD has strong correlation with the phenotype.