Are carriers of CYP21A2 mutations less vulnerable to psychological stress? A population-based national cohort study.

BACKGROUND: Congenital adrenal hyperplasia (CAH) is one of the most common monogenic autosomal recessive disorders with an incidence of one in 15 000. About one in 70 individuals in the general population are carriers of a severe CYP21A2 mutation. It has been suggested that this confers a survival advantage, perhaps as a result of increased activity in the hypothalamic-pituitary-adrenal axis. We investigated vulnerability to psychological stress in obligate carriers. METHOD: The Swedish CAH Registry encompasses more than 600 patients. Parents, that is obligate carriers of the CYP21A2 mutation, were identified through the Multigeneration Register. The diagnosis of the child was used as the psychological stressor. Psychiatric diagnoses before and after the birth of a child with CAH were compared to those of controls derived from (i) the general population, (ii) parents of children with hypospadias and (iii) parents of children with diabetes mellitus type 1 (T1DM). RESULTS: Parents of children with CAH had less risk of being diagnosed with any psychiatric disorder (OR, 0·6), an affective disorder (OR, 0·5) or substance misuse (OR, 0·5) after the diagnosis of the child, compared to the general population. Their risk was also decreased compared to parents of a child with hypospadias (OR, 0·6, 0·4 and 0·2, respectively) and parents of a child with T1DM (OR 0·7, 0·6 and 0·2, respectively). The CYP21A2 carriers had a lower risk of developing mood and stress-related disorders after the diagnosis of the child. CONCLUSION: Obligate CYP21A2 carriers had a reduced risk of a psychiatric diagnosis and were less vulnerable to a psychologically stressful situation, at least with respect to receiving a psychiatric diagnosis. This indicates a better ability to cope with psychological stress among heterozygous carriers of severe CYP21A2 mutations, which may contribute to the apparent survival advantage.