The genetic contribution to hand osteoarthritis

Area of Science:

• Genetics
• Rheumatology
• Epidemiology

Background:

• Hand osteoarthritis (OA) is a prevalent degenerative joint disease.
• Understanding the etiology of hand OA, including genetic factors, is crucial for effective management and prevention strategies.

Purpose of the Study:

• To estimate the genetic contribution to doctor-diagnosed hand osteoarthritis (OA).

Main Methods:

• A 20-year population-based longitudinal cohort study of 59,970 twins from the Swedish Twin Registry and National Patient Register.
• Inpatient and outpatient doctor-diagnosed hand OA (affecting distal/proximal interphalangeal and/or carpometacarpal joints) were identified using ICD-10 codes from 1997-2016.
• Intra-pair correlations and heritability were calculated to estimate the genetic influence on hand OA.

Main Results:

• The heritability of hand OA (any joint) was estimated at approximately 87%.
• Specific joint involvement showed varying heritability: carpometacarpal OA (CMC-1 OA) at ~86% and distal/proximal interphalangeal OA (DIP/PIP OA) at ~48%.
• Identical twins diagnosed with hand OA had a significantly higher risk (HR=6.98) of their co-twin also being diagnosed compared to fraternal twins.

Conclusions:

• The genetic contribution to hand OA is substantial, with heritability estimates ranging widely from 48% to 87%.
• Further research is warranted to explore potential differential heritability across various hand OA phenotypes.