Chromosomal abnormality that causes inherited clubfoot found

WASHINGTON - Scientists at Washington University School of Medicine in St. Louis have found what they believe to be the most common cause of inherited clubfoot yet discovered.

By performing a routine genetic screening on 66 patients with an inherited form of clubfoot, Dr. Christina Gurnett, and her colleagues found abnormalities in a region of chromosome 17 in four patients.

Three of the patients had small recurrent DNA duplications, and one had a small recurrent DNA deletion on chromosome 17.

“What we’re learning about birth defects is that for some genes involved in very early fetal development, if you have either too much or too little of them, you may develop the same condition. This appears to be the case for clubfoot,” said Gurnett.

The researchers ran a test commonly used to evaluate children for neurodevelopmental disorders such as autism called a chromosomal microarray.

Gurnett said that it was the first time researchers used this kind of test specifically for isolated clubfoot.

“Since few genes have previously been implicated in clubfoot, this discovery represents the most common cause of isolated clubfoot found to date. This technology can be used immediately for genetic testing,” said Gurnett.

“Our findings are significant in that they were present in 6 percent of familial clubfoot cases tested and were associated with clubfeet that were rigid and prone to a difficult treatment course,” said Dr. Matthew B. Dobbs Dobbs, co-author of the study.

“Hip abnormalities, including hip dysplasia, were also seen in some of the patients. These genetic findings may allow orthopaedic surgeons to better predict response to clubfoot treatment and also to identify a clubfoot patient group that may need careful hip screening as well,” he added.

“We may be hitting the tip of the iceberg. Now that we have identified a particular gene abnormality these patients have in common, we are looking at X-rays of the feet and other bones to obtain more clues about what’s going on in these and other patients,” said Gurnett.

They are now screening DNA from 1,000 patients with clubfoot to look for additional DNA duplications or deletions on chromosome 17.

The results will be published in the July 9 issue of the American Journal of Human Genetics. (ANI)