Neonatal screening for congenital adrenal hyperplasia in Japan.

A nationwide screening test for congenital adrenal hyperplasia (CAH) was first initiated in Japan in 1989, over 20 years ago, and it is now 30 years since a pilot study was initiated in Sapporo in 1982. The incidence of 21-hydroxylase deficiency in Japan is about 1/18,000 persons, which is similar to that in other countries. The effectiveness of early detection and treatment of CAH in Japan has been demonstrated by cost-benefit analyses. However, the false-positive rate of CAH screening in preterm infants remains high compared to screening tests for term infants. To improve the positive predictive value, we have employed 21-hydroxylase gene (CYP21A2) analysis on dried blood spots and high performance liquid chromatography (HPLC) to measure 17-hydroxyprogesterone, and currently use tandem mass spectrometry (LC-MS/MS) as a screening technique. We suggest that LC-MS/MS should be used in the future to improve the accuracy of CAH screening in Japan.