Pharmacogenomic markers of glucocorticoid response in congenital adrenal hyperplasia

Abstract

Glucocorticoids (GC) replacement are the mainstay treatment for 21-hydroxylase deficiency (21-OHD), the most common cause of congenital adrenal hyperplasia (CAH), in its classical form. There are novel insights into the genetic basis of the GC action diversity that point to an important role for GC receptor (GR) gene polymorphisms, suggesting a possible modulation in occurrence of metabolic disorders, what may be relevant to clinical management of 21-OHD. The aim of this study was to investigate whether the five GR gene polymorphisms Tth111I, ER22, 23EK, BclI, 9β (rs10052957, rs6189, rs6190, rs41423247, rs6198) and their combination into haplotypes are associated to different GC response in a cohort of classic 21-OHD subjects. GR genotype-phenotype associations were explored after a dexamethasone suppression test using very low-doses (VLD-DST), 20 and 40 μg/m². The final sample (n = 28) was selected based on the 102 individuals’ previous genotypes classification, according to literature data of GC sensitivity or resistance. Thus, only patients with GC increased resistance (n = 18) or increased sensitivity (n = 10) profiles were selected. Out of 28 subjects aged 12 (2–34) years enrolled in this study, 75% were females, 75% presented the salt-wasting form (SW) and 25% the simple virilizing form (SV). Subjects who carried Tth111I and 9β, associated or not to the ER22/23EK variants, showed an impaired DST response. Results did not differ significantly according to gender or body mass index. SV subjects with GC hypersensitivity-genotypes showed decreased average cortisol levels compared to those with GC resistance-genotypes (p = 0.0023). The Tth111I + 9β/ Wild or Tth111I + ER22/23EK + 9β/ Wild genotypes were associated to GC resistance in this population. This finding may be relevant given the challenges posed by therapeutic management with GC in CAH.

Drug–Drug Interactions Involving Dexamethasone in Clinical Practice: Myth or Reality?

“…The role of these various SNPs in predicting the dexamethasone level of enzyme or transporter induction in humans is still unknown and will be presumably challenging in the future of personalized medicine. Indeed, to date, the best-described and relevant SNPs do not concern the proteins involved in dexamethasone pharmacokinetics and metabolism/transport, but rather pharmacodynamics and targets such as chaperone or the glucocorticoid receptor [136][137][138][139][140]. However, specific association with ABCB1 genetic polymorphisms (rs1128503, rs2032582 and rs1045642) and dexamethasone, but not prednisone or hydrocortisone efficacy, has been observed in children with congenital adrenal hyperplasia [137].…”