Polymorphism in the Drug Transporter Gene ABCB1 as a Potential Disease Modifier in Cortisol-Producing Adrenal...

Area of Science:

• Endocrinology
• Genetics
• Metabolomics

Background:

• Endogenous hypercortisolism exhibits variable clinical presentations, with limited understanding of factors influencing hypercortisolism levels or comorbidity severity.
• The adrenal ATP-binding cassette B1 (ABCB1) gene has recently been identified as a regulator of glucocorticoid secretion.

Purpose of the Study:

• To investigate the impact of the ABCB1 gene polymorphism rs2032582 on the steroid metabolome and clinical characteristics of patients diagnosed with endogenous hypercortisolism.

Main Methods:

• A cross-sectional cohort study involving 137 patients from the German Cushing's registry.
• Analysis of ABCB1 polymorphism rs2032582 using TaqMan genotyping.
• Quantification of 24-hour urinary glucocorticoid metabolite excretion via gas chromatography-mass spectrometry and systematic clinical phenotype assessment.

Main Results:

• In patients with cortisol-producing adrenal adenomas, the homozygous major allele GG of ABCB1 rs2032582 was linked to increased overall cortisol metabolite excretion and elevated levels of major cortisol metabolites (αTHF, THF, THE).
• These patients also exhibited higher mean arterial pressure compared to minor homo- and heterozygotes.
• No significant association was observed in patients with ACTH-producing pituitary adenomas.

Conclusions:

• The genotype of the ABCB1 rs2032582 polymorphism is associated with cortisol metabolite secretion levels in cortisol-producing adrenal adenomas.
• This genetic variation may function as a modifier of disease severity in this specific patient group.