Clinical genetics
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Newborn screening (NBS) identifies the majority of classical [salt-wasting (SW) and simple-virilizing (SV)] cases of congenital adrenal hyperplasia (CAH) due to 21α-hydroxylase (21α-OHase) during the first days of life. Diagnosis of classical CAH is confirmed by follow-up serum 17-hydroxyprogesterone and/or the adrenocorticotropin stimulation test; however, neither test definitively distinguishes between the classical subtypes. After confirmation, all newborns are started on hydrocortisone (glucocorticoid) and fludrocortisone (mineralocorticoid) treatment. ⋯ Molecular testing on 39 patients (25 identified by NBS) with an already established diagnosis of CAH identified 11 SW patients (8 identified by NBS) whose mutations suggested further biochemical and clinical reassessment of their subtype. Overall, SW accounted for 57.6% of our classical CAH patients, below the generally accepted figure that >75% of classical CAH are comprised of the SW form. In the era of NBS, molecular testing is a valuable supplemental tool identifying patients who may benefit from reassessment of their salt-retaining ability.