ATLANTA – Got bunions? Thank your parents. Bunions were inherited in 89% of adults younger than 60 years, according to genetic data from more than 2,000 adults that were presented at the annual scientific meeting of the American College of Rheumatology.
Bunions and other foot disorders can limit mobility and exacerbate other musculoskeletal weaknesses, but interventions are available, and they are most effective if foot deformities are identified early, said Marian Hannan, D.Sc., of Harvard Medical School, Boston.
Foot disorders occur in 20%-60% of adults, and researchers have long suspected genetic involvement, but this study is the first to examine specific associations between genes and foot deformities, Dr. Hannan said.
Dr. Hannan and her colleagues reviewed data from 959 men and 1,220 women in the Framingham Foot Study of 2002-2005. A trained examiner evaluated the study participants for any of 20 different foot disorders. In this study, Dr. Hannan reported data about the most common and least common of the disorders: hallux valgus (bunions) and pes cavus (high arches).
Overall, 675 individuals (31%) had bunions and 154 (7%) had high arches. A bunion was defined as a big toe angled at least 15 degrees toward the first metatarsal. High arches were identified by calculating weight-bearing arch width.
The researchers used statistical genetics software to determine the heritability of the two conditions. Across all ages, 39% of women and 38% of men inherited their bunions, and 68% of women and 20% of men inherited their high arches. Among individuals younger than 60 years, 99% of women and 63% of men inherited their high arches. The heritability estimates were statistically significant for both conditions.
The average age of the study participants was 66 years, and 57% were women.
"Known interventions can slow the progression of disease" for patients with foot problems, Dr. Hannan emphasized. "We are continuing with research within the Framingham Foot Study to look at the other 18 foot conditions," she added. "We are also looking at specific genetic analyses to see what specific gene might be behind what is going on."
Dr. Hannan had no financial conflicts to disclose.