FALSE NEGATIVES AT NEONATAL SCREENING FOR CONGENITAL ADRENAL-HYPERPLASIA IN 2 SIBLINGS WITH 21-HYDROXYLASE DEFICIENCY

We report on two siblings with classic simple virilizing 21-hydroxylas e deficiency whose neonatal screening for serum 17 alpha-hydroxyproges terone(17-OHP) gave normal results. The proband, a girl with clitorome galy whose screening 17-OHP value had been 9.2 ng/ml, was diagnosed at the age of 6 months, and her elder brother with the initial screening level of 15.7 ng/ml was diagnosed at the age of 6 years due to precoc ious puberty. Although the occurrence of false-negative cases is extre mely rare, it can happen in a simple virilizing form of 21-hydroxylase deficiency. This experience informs that normal results for neonatal screening cannot be an excuse for not evaluating siblings of the proba nd with congenital adrenal hyperplasia.