9240 Role Of Genetics In The Age-Related Testosterone Decline In Men: A UK Biobank Study

Abstract

Abstract Disclosure: L. Ogoniak: None. S. Sandmann: None. J. Varghese: None. A.S. Busch: None. Background: Age-related decline in circulating serum testosterone concentrations is a well-established phenomenon in men. While the decline is partially linked to comorbidities such as obesity, type 2 diabetes (T2D), and cardiovascular disease (CVD), healthy ageing men present with rather stable levels. Recent genetic mapping studies demonstrated a large influence of common genetic variation on testosterone levels in men. However, increasing incidence rates of comorbidities in the ageing population are posing a challenge for the disentanglement of effects. Objective: Our study aims to investigate the genetic component of age-dependent testosterone decline in men. We hypothesize that the decline in testosterone levels in ageing men is primarily influenced by comorbidities, without significant alterations in the genetic architecture of testosterone levels. Material and Methods: We included 6,406 men with baseline and follow-up measurements of circulating serum concentrations of total testosterone (T), bioavailable testosterone (BAT) and sex hormone-binding globulin (SHBG) representing an independent sub-cohort of the UK Biobank study. We 1) assessed the association of baseline levels with the decline in sex steroids and 2) developed and verified polygenic risk score (PRS) models for T, BAT and SHBG based on 183,909 men from the UK Biobank (sub cohorts: 70% base, 15% target and 15% validation, follow-up cohort excluded for PRS development). Results: In the follow-up sub cohort, mean age (SD) at baseline was 58.2 yrs ( 7.5) and mean (SD) follow-up period was 4.3 (1.0) yrs. Mean (SD) BAT at baseline were 5.2 (1.32) nmol/L with a mean (SD) decline of 1.6 (24.4) % at follow-up. Baseline BAT, T and SHBG levels were significantly associated with the relative change of the respective biomarker at follow-up (-7.8, -2.9 and -0.4% per nmol/L, respectively, all p <0.001). After correcting for age at baseline, follow-up period and principal components 1-10, PGSTestosterone and PGSBAT were not associated with relative decline of the respective biomarker (both p = n.s.). Conclusion: Our study did not find evidence supporting a genetic component in the age-related decline of circulating serum T or BAT concentrations. Instead, in accordance to previous observational studies, our results suggest that rather non-genetic factors, e.g. increasing incidence rates of comorbidities, drive the age-related decline in sex steroid levels in men. Our study contributes to understanding the intricate relationship between genetic and non-genetic factors with age-related testosterone decline in men and offers valuable insights for potential interventions targeting age-related hormonal changes and associated health outcomes. Presentation: 6/2/2024