The diagnosis of non-classical (NC) 21-hydroxylase deficiency (21-OH-D) was substantiated by the finding of increased baseline and adrenocorticotropic hormone (ACTH)-stimulated 17-hydroxy-progesterone levels and was supported by molecular analyses of the CYP21A2 gene, which revealed V281L homozygosis in patient 1 and V281L/P30L compound heterozygosis in patient 2.
The most frequent mutation in Romanian patients with 21-hydroxylase deficiency was I2G (43.9%), followed by deletions and large conversions (16.7%), I172N and the triple mutation (P30L+I2G+del8bp), accounting for 12.1% each, P30L (7.6%) and R356W (1.5%).
Therefore, these substitutions in synergism with the P30L mutation might decrease the enzyme activity resulting in a more severe phenotype, and a DNA sequence of -167 bases of the CYP21A2 gene should be performed in patients with 21-hydroxylase deficiency in whom the phenotype is more severe than predicted by the genotype.
We suggest that P30L mutation is more frequent in Japanese NC CAH than V281L and that the frequency of the mutations causing NC steroid 21-hydroxylase deficiency in Japan might be different from that in western countries.