Congenital adrenal hyperplasia (CAH) is an inherited disorder caused by the absence or severely impaired activity of steroidogenic enzymes involved in cortisol biosynthesis. More than 90% of cases result from 21-hydroxylase deficiency (21OHD). To prevent life-threatening adrenal crisis and to help perform appropriate sex assignments for affected female patients, newborn screening (NBS) programs for the classical form of CAH have been introduced in numerous countries. In Japan, the NBS for CAH was introduced in 1989, following the screenings for phenylketonuria and congenital hypothyroidism. In this review, we aim to summarize the experience of the past 30 years of the NBS for CAH in Japan, composed of four parts, 1: screening system in Japan, 2: the clinical outcomes for the patients with CAH, 3: various factors that would impact the NBS system, including timeline, false positive, and LC-MS/MS, 4: Database composition and improvement of the screening program.
Keywords: 21-hydroxylase deficiency; congenital adrenal hyperplasia; newborn screening.