Hemochromatosis Genetic Variants and Musculoskeletal Outcomes: 11.5-Year Follow-Up in the UK Biobank Cohort Study.

The iron overload disorder hemochromatosis is primarily caused by the homozygous p.C282Y variant, but the scale of excess related musculoskeletal morbidity is uncertain. We estimated hemochromatosis-genotype associations with clinically diagnosed musculoskeletal outcomes and joint replacement surgeries in the UK Biobank community cohort. A total of 451,143 European ancestry participants (40 to 70 years at baseline) were followed in hospital records (mean 11.5-years). Cox proportional hazards models estimated p.C282Y and p.H63D associations with incident outcomes. Male p.C282Y homozygotes ( = 1294) had increased incidence of osteoarthritis ( = 52, hazard ratio [HR]: 2.12 [95% confidence interval, CI: 1.61 to 2.80];  = 8.8 × 10), hip replacement ( = 88, HR: 1.84 [95% CI: 1.49 to 2.27];  = 1.6 × 10), knee replacement ( = 61, HR: 1.54 [95% CI: 1.20 to 1.98];  = 8.4 × 10), and ankle and shoulder replacement, compared to males with no mutations. Cumulative incidence analysis, using Kaplan-Meier lifetable probabilities demonstrated 10.4% of male homozygotes were projected to develop osteoarthritis and 15.5% to have hip replacements by age 75, versus 5.0% and 8.7% respectively without mutations. Male p.C282Y homozygotes also had increased incidence of femoral fractures ( = 15, HR: 1.72 [95% CI: 1.03 to 2.87];  = 0.04) and osteoporosis ( = 21, HR: 1.71 [95% CI: 1.11 to 2.64];  = 0.02), although the latter association was limited to those with liver fibrosis/cirrhosis diagnoses. Female p.C282Y homozygotes had increased incidence of osteoarthritis only ( = 57, HR: 1.46, [95% CI: 1.12 to 1.89];  = 0.01). Male p.C282Y/p.H63D compound heterozygotes experienced a modest increased risk of hip replacements ( = 234, HR: 1.17 [95% CI: 1.02 to 1.33],  = 0.02), but this did not pass multiple testing corrections. In this large community cohort, the p.C282Y homozygote genotype was associated with substantial excess musculoskeletal morbidity in males. Wider genotype testing may be justified, including in orthopedic clinics serving higher variant prevalence populations. © 2023 The Authors. published by Wiley Periodicals LLC. on behalf of American Society for Bone and Mineral Research.