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.”

The American College of Rheumatology is an international professional medical society that represents more than 8,000 rheumatologists and rheumatology health professionals around the world. Its mission is to advance rheumatology. The ACR/ARHP Annual Scientific Meeting is the premier meeting in rheumatology. For more information about the meeting, visit http://www.rheumatology.org/education. Follow the meeting on twitter by using the official hashtag: #ACR2010.

Editor’s Notes: Dr. Hannan, will present this research during the ACR Annual Scientific Meeting at the Georgia World Congress Center from 9 – 11 AM on Tuesday, November 9 in Hall B1 & B2. Dr. Hannan will be available for media questions and briefing at 1:30 PM on Monday, November 8 in the on-site press conference room, B 212.

Learn more about living well with rheumatic disease as well as rheumatologists and the role they play in health care.

Presentation Number: 1329

Hallux Valgus and Pes Cavus Are Highly Heritable in Older Men and Women: The Framingham Foot Study.
Marian T. Hannan, DSc, MPH (Institute for Aging Research, Hebrew SL & Harvard Medical School, Boston, MA)
Yi-Hsiang Hsu, PhD (Hebrew SeniorLife & Harvard Medical School, Boston MA)
L. Adrienne Cupples, PhD (Boston University School of Public Health, Boston MA)
Joanne M Jordan, MD (University of North Carolina, Chapel Hill NC)

Body: Foot disorders are common among adults, affecting 20-60% of adults and often linked to mobility limitations. Although genetics are commonly suspected in foot disorders, only one family aggregation study has been done, reporting that 90% of 350 participants with hallux valgus had a family history, and inheritance may be an autosomal dominant transmission. To our knowledge, no other studies have examined the association between foot disorders and genetics in humans. We have the unique opportunity to link data that we have collected on specific foot disorders to a wealth of genetic data in the community-based Framingham Study. Our aim was to evaluate the possible heritability of two common foot disorders, using the pedigree structure in the Framingham Study.

The Framingham Foot Study (n=2179) was designed to examine common foot disorders and functional limitations. A trained examiner used a validated foot exam to assess 20 foot disorders in 2179 participants between 2002-2005. Of participants, 959 men and 1220 women had been genotyped. We estimated overall, sex-specific and age (

< 60, 60+y) heritability of hallux valgus and pes cavus (our most common and least common foot disorders) in the Framingham participants. Hallux valgus (present/absent) was defined as the angular deviation of the hallux with respect to the first metatarsal toward the lesser toes at >

=15. Pes cavus was defined using a digital recording of foot pressure while walking (MatScan pedobarographic device, Tekscan, Inc. Boston MA), that allowed calculation of the ratio of arch width (medial to lateral, to nearest 0.01 cm) to heel width. Pes cavus was defined as either foot as having a weight-bearing arch width=0, regardless of heel width. We estimated heritability of hallux valgus and pes cavus by the threshold model of a standard quantitative genetic variance-components model implemented in the Sequential Oligogenic Linkage Analysis Routines (SOLAR) package.

Mean age was 66y (range 39-99y); 57% were female. The prevalence of hallux valgus (HV) was 31% (675 hallux valgus cases with available pedigree structure). The overall HV heritability was 0.39 for women and 0.38 for men. For persons aged < 60y, the HV heritability was 0.89. The prevalence of pes cavus (PC) was only 7% (154 cases with available pedigree structure have pes cavus). The PC heritability was 0.68 for women and 0.20 for men. For individuals < 60y of age, the PC heritability was 0.99 for women and 0.63 for men. Thus, hallux valgus and pes cavus are highly heritable, especially for younger adults.

This study breaks new ground in an area that has received very little attention, yet is critically important to public health. Our study documented for the first time, the high heritability (strongly suspected by many) of two specific foot disorders phenotypes. Foot disorders are common and it is important to identify persons at high risk, as effective interventions exist and may also be targeted to individuals to lessen the impact of foot disorders or prevent development. Genome-wide association analyses are planned to identify potential genetic determinants for these common foot disorders.

Disclosures: Marian T. Hannan: nothing to disclose; Yi-Hsiang Hsu: nothing to disclose; L. Cupples: nothing to disclose; Joanne Jordan: nothing to disclose.

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Source:  American College of Rheumatology (ACR)