Three Novel Mutations in Japanese Patients with 21-Hydroxylase Deficiency

<i>Objective:</i> This study analyzed the mutation of 21-hydroxylase deficiency (21-OHD) in 36 unrelated Japanese patients with congenital adrenal hyperplasia (CAH). <i>Methods:</i> All the exons of the functional CYP21 gene <i>(CYP21A2)</i> were analyzed by polymerase chain reaction (PCR) and PCR direct sequencing. <i>Results:</i> Apparent gene deletions and conversions were present in 23.6% of the 72 CAH alleles, in which the most frequent mutation was the IVS2-13 A/C>G (27.8%), followed by I172N (26.3%), consistent with the frequencies reported for other countries. Previously described mutations were not present in three unrelated cases. Sequence analysis of the complete functional <i>CYP21A2</i> gene revealed three, not yet described mutations that represent a common pseudogene sequence. These three putative novel mutations are located in exon 1 (M1I), in exon 5 (1210–1211insT), and in exon 3 (R124H). <i>Conclusions:</i> In this study, we have identified three putative novel mutations. It remains to be determined whether these three mutations are responsible for the significant number of as yet uncharacterized CAH patients in Japan.