A chromosomal mutation responsible for a very rare condition in which people grow excess hair all over their bodies has been discovered by an Indian-origin researcher and her team.
Investigators hope the finding ultimately will lead to new treatments for this and less severe forms of excessive hair growth as well as baldness.
Pragna Patel, professor in the Keck School of Medicine of the University of Southern California (USC) is a co-investigator of the study and Sunju Choi, a research associate in Patel's lab, is a co-first author.
The principal investigator is Xue Zhang, professor and chair of medical genetics at the Peking Union Medical College.
The initial discovery of the mutation came from Zhang's lab, which examined the condition, known as CGH, in a Chinese family.
Researchers there worked with Choi to confirm the finding in a Mexican family that Patel first began studying in 1993.
Males with this disorder have hair covering their entire face including their eyelids and their upper body, while females have thick patches of hair on their bodies.
"In 1995, we traced the approximate location of the mutation responsible for CGH to a section of the X chromosome in the Mexican family," said Patel.
"We sequenced nearly 100 genes but could not find any mutations. Then recently, Xue Zhang and his colleagues in Beijing were able to pinpoint the exact location, discovering that there was an insertion of chromosome 5 into the X chromosome in the Chinese family.
"When the Mexican family was examined, a piece of chromosome 4 was found to be inserted into the same part of the X chromosome, thus confirming that these extremely rare events caused the disorder," she said.
The investigators suggest that insertion of the "extra" DNA sequences into the X chromosome apparently turns on a gene, likely SOX3, located near the insertion site. SOX3 is a strong candidate because other members of this gene family have been shown to play a role in hair growth.
The study appeared in the June 2, 2011 issue of the American Journal of Human Genetics.