O papel da análise molecular do gene CYP21 nos programas de triagem neonatal para hiperplasia adrenal congênita

Abstract

Congenital adrenal hyperplasia (CAH) is suitable for newborn screening, as it is a common and potentially fatal disease which can be easily screened by a simple hormonal measurement. The main difficulty found by Neonatal Screening Programs (NSP) for CAH is the high incidence of false-positive results due to a low specificity of the test and a transitory hyper-17-hydroxyprogesteronemia usually found in preterm newborns The objective of this study was to evaluate the role of molecular analysis of the CYP21 gene as a second tier test in neonatal screening for CAH. Molecular analysis of CYP21 is already used as an adjunct test in many NSP around the world. It is mainly used for the distinction of severe salt wasting forms from the other forms of the disease (simple virilizing or non-classic). Molecular analysis was also shown to be useful in diagnosing indefinite cases. When it comes to treatment of CAH, genotyping is able to avoid the delay of hormonal reposition in boys with the simple virilising form and also can avoid an inadequate treatment for healthy patients. Early diagnosis also benefits the families of healthy false-positive newborns, reducing the time of stress and anxiety to which they are submitted. As a second tier exam in neonatal screening for CAH, molecular analysis is a definitive exam with great importance not only in clarifying indefinite cases, but also in excluding healthy newborns who were considered sick. Studies have shown a good costbenefit in adopting this exam in NSP for CAH.