title: Genetic risk load and age at symptom onset of knee osteoarthritis.
abstract: To test whether a higher genetic risk load for knee osteoarthritis (OA) is associated with an earlier age at symptom onset. Six polymorphisms in GDF5, PTGS2, 7q22 locus, DVWA, DIO3, and ASPN that have been associated with knee OA were analyzed in 255 patients that had undergone total knee replacement (TKR) because of primary OA and in 457 healthy controls. We looked for association between the number of risk alleles in each patient and his age at symptom onset with linear regression and t-tests between the upper and lower quartiles. There was not even a weak trend in the direction of a younger age at symptom onset in the patients carrying more risk alleles. Patients in the upper quartile of age at symptom onset (67.0 ± 2.8 years) carried the same number of OA risk alleles (5.4 ± 1.4 vs. 5.3 ± 1.0) than patients in the lower quartile (44.6 ± 5.5 years). We did not find any evidence in support of the hypothesis of an earlier knee OA symptom onset associated with higher genetic risk load as determined by the six loci. This result suggests that old age and genetic risk act as independent factors in the pathogenesis of OA. It also indicates that designing OA genetic studies with patients selected for early symptom onset will not provide any substantial power gain.
authors.affiliation: Laboratorio Investigacion 10, Rheumatology Unit, Instituto Investigacion Sanitaria, Hospital Clinico Universitario de Santiago, Travesia Choupana sn., 15706 Santiago de Compostela, Spain.
authors.forename: Cristina
authors.initials: C
authors.lastname: Rodriguez-Fontenla
authors.forename: Yolanda
authors.initials: Y
authors.lastname: López-Golán
authors.forename: Manuel
authors.initials: M
authors.lastname: Calaza
authors.forename: Manuel
authors.initials: M
authors.lastname: Pombo-Suarez
authors.forename: Juan J
authors.initials: JJ
authors.lastname: Gómez-Reino
authors.forename: Antonio
authors.initials: A
authors.lastname: González
mesh_terms: D000367:Age Factors; D017668:Age of Onset; D000368:Aged; D000369:Aged, 80 and over; D005260:Female; D020022:Genetic Predisposition to Disease; D006801:Humans; D008297:Male; D008875:Middle Aged; D020370:Osteoarthritis, Knee / Q000175:diagnosis* / Q000453:epidemiology / Q000235:genetics*; D020641:Polymorphism, Single Nucleotide; D012307:Risk Factors; D013030:Spain / Q000453:epidemiology