Study finds high heritability of common foot disorders

Foot disorders might be passed down from one generation to the next, according research presented this week at the American College of Rheumatology Annual Scientific Meeting in Atlanta.

Foot disorders are common among adults—affecting 20 to 60 percent—and can often cause mobility limitations. One foot disorder, hallux valgus, occurs when a person's big toe (called the 'hallux') angles toward his or her pinky toe (a condition called 'valgus'). Another disorder, pes cavus (more commonly called high arched feet), is where the bottom of the foot is overly-arched and hollowed - even when bearing weight.

In a study funded in part by the ACR Research and Education Foundation, researchers recently looked at the link between hallux valgus, pes cavus and heredity as a part of the the Framingham Foot Study—a study that examined common foot disorders and the functional limitations they cause in 2,179 participants from 2002 through 2005—to evaluate whether these common foot conditions are inherited.

Out of the larger group of study participants, 675 participants (31 percent) with hallux valgus and 154 participants (seven percent) with pes cavus were identified. The average age of these participants was 66 years, and 57 percent were female.

When analyzed using statistical genetics software, researchers found that hallux valgus was inherited in approximately 39 percent of the women and 38 percent of men in the study. They also found that, 89 percent of the participants under the age of sixty inherited the condition. These estimates of heritability are highly statistically significant. Additionally, in the subjects with pes cavus, 68 percent of the women and 20 percent of the men in this group were found to have inherited the condition. And, surprisingly, of those under the age of 60 with pes cavus, 99 percent in women and 63 percent in men were inherited.

"To our knowledge, no other study has examined these associations in humans before," explains Marian T. Hannan DSc, MPH; associate professor of medicine, Harvard Medical School, and lead investigator in the study. These results document, for the first time, the high likelihood (which has been suspected by many) that hallux valgus and pes cavus can be inherited.

Hannan goes on to say, "the high heritability that we found is of great interest, especially for the younger ages [under 60 years], because effective interventions are available and, as with most public health interventions, are most effective in the early stages."