Accidental Discovery From Rare Disorder Study May Help Prevent Breast Cancer, Body Odor

Irvine, Calif., June 13, 2002 -- Earwax production is controlled by a gene linked to a very rare movement disorder, UC Irvine and Japanese researchers have found.

The findings, published in the June 8 issue of Lancet, demonstrates how rare disorders can uncover genetic relationships within the body and may help researchers prevent cancer and excessive body odor.

Dr. Hiroaki Tomita, a postdoctoral fellow at UCI's department of psychiatry, and his colleagues in Japan found from studying the gene for a rare genetic disorder called paroxysmal kinesigenic choreoathetosis (PKC) that the gene for producing earwax was in the same area as the gene for PKC. Earwax comes in two types--the "wet" variety seen most often in Caucasians and African-Americans, and the "dry" variety common among Asians and Native Americans.

"A woman in our PKC study said that her family members who had the disease also had the 'wet' form of earwax, which is less common in Japan," Tomita said. "We already knew where the gene for PKC was located, and we found the likely genes for producing earwax in the same chromosome region responsible for producing PKC."

The researchers, working in Japan, studied 92 members of eight families who had at least one member with PKC and found the gene for earwax on the 16th chromosome, exactly where the gene for PKC is located. The same team discovered the location of the PKC gene in 1999.

While the two genes do not appear to regulate each other, a gene for PKC happens to be located very closely to the gene for earwax. It is not known how the mutations came to lie closely to each other on the 16th chromosome.

The glands that secrete earwax are called ceruminal glands, which are part of a family of organs called apocrine glands. Apocrine glands are found in the armpits and breast. Previous research has suggested a relation between wet earwax and higher rates of breast cancer, which could be connected by the gene that produces earwax and controls apocrine gland function. Apocrine glands also produce sweat in the armpit and contribute to body odor.

"There is not much information about how the apocrine glands are regulated and how they operate," Tomita said. "We've located the position of this gene on the 16th chromosome, but we now need to determine its exact sequence and starting and ending points. If we can pinpoint this, it might give us a better understanding of how earwax, sweat and apocrine secretions in the breast are controlled. Once pinpointed, characterizing a responsible gene for earwax may contribute to the understanding of apocrine gland development, body odor and breast cancer."

Tomita, a postdoctoral fellow at UCI for the past two years, continues to work with his Japanese colleagues on finding more information about the gene responsible for PKC, as well as for earwax and other apocrine gland functions.

Tomita came to UCI from the Nagasaki University School of Medicine. His colleagues include Dr. Koki Yamada, Dr. Mohsen Ghadami, Takako Ogura, Yoko Yanai, Dr. Yatsumi Nakatomi and Dr. Norio Niihawa of Nagasaki University, Dr. Miyuki Sadamatsu and Dr. Nobumasa Kato of the University of Tokyo and Dr. Akira Matsui of Shiga University of Medical Science.

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