Long-term effects of pre-and postnatal glucocorticoid treatment in congenital adrenal hyperplasia

Sammanfattning: Congenital adrenal hyperplasia (CAH) is an autosomal recessive disorder mostly caused by mutations in the CYP21A2 gene leading to impaired production of cortisol and aldosterone. Precursors in the steroidogenic pathway are shunted to pathways of androgen production and elevated levels of androgens may cause virilization of the external genitalia in females with CAH already in utero. Prenatal treatment with the synthetic glucocorticoid (GC) dexamethasone (DEX) can ameliorate virilization of the female fetus but because of the recessive mode of the inheritance of CAH and that treatment has to be initiated before the genotype of the fetus can be determined, the majority of the treated cases will be unnecessarily exposed to DEX during fetal life. Moreover, patients with CAH require GC replacement therapy after birth and during their life span there may be episodes of over- or under-treatment with a risk of developing adverse effects. Side effects of pre-and postnatal GC exposure may develop into chronic conditions with permanent effects on growth, metabolism, cognition, behavior and normal immune functioning. In this study, the effects of prenatal DEX treatment and postnatal GC treatment in the context of CAH were evaluated in a cohort of 265 individuals. The cohort comprised DEX-treated individuals with and without CAH, patients with CAH not prenatally treated with DEX and controls from the general population. The long-term impact on cognition, behavior, brain morphology, metabolism and DNA methylation was studied. Prenatal treatment with DEX was associated with cognitive impairments, particularly working memory. The effects seem to normalize by adult age in individuals without CAH who were treated with DEX during the first trimester of fetal life. In patients with CAH, prenatal DEX therapy was associated with reduced thickness and surface area bilaterally of a large area encompassing the parietal and superior occipital cortex. Moreover, the effects of DEX treatment on DNA methylation were associated with alterations in the DNA methylation profile, denoting an altered epigenetic programming of the immune system and, in particular, inflammation in individuals without CAH treated in the first trimester. This finding may confer altered risks for immune-related disorders later in life. When looking at the long-term outcome in patients with CAH, patients showed deficits in tests measuring executive functioning. Deficits in spatial working memory were associated with decreased white matter integrity that, in turn, was associated with lower dosages of GCs. Patients also showed structural alterations in the prefrontal regions involved in executive functioning and in areas of the parietal and superior occipital cortex involved in sensory integration. In addition, patients exhibited reduced cerebellar volume. In our analysis of DNA methylation in patients with CAH, we identified hypermethylation in two CpGs in two genes (FAIM2 and SFI1). Methylation was associated with the severity of CAH and brain structure, but we could not identify any association between methylation in these two genes and metabolic or cognitive outcome. In conclusion, this study extends our knowledge about the effects of pre-and postnatal GC treatment in CAH. The results have implications for the use of prenatal DEX treatment.