Magazine article Science News

Genes Linked to Baldness, Missing Teeth

Magazine article Science News

Genes Linked to Baldness, Missing Teeth

Article excerpt

More than a century after Charles Darwin described a family in India in which 10 men had sparse hair, small teeth, and "excessive dryness of the skin" during hot weather, scientists have pinned the blame for the malady on a gene-the first linked to baldness.

Anand K. Srivastava of the J.C. Self Research Institute of Human Genetics in Greenwood, S.C., and his colleagues report in the August Nature Genetics that they have isolated a gene which, when faulty, causes the Indian family's complaint, now known as anhidrotic ectodermal dysplasia. The researchers also pinpointed the specific mutations and deletions that cause the pattern of symptoms Darwin described.

Anhidrotic ectodermal dysplasia is one of 150 syndromes marked by defects in skin, hair, teeth, and nails. Together, these syndromes afflict 125,000 people in the United States.

Though it may seem odd that anomalies in a single gene can affect such distinctly different bodily features as hair, teeth, and sweat glands, the trio is linked by a basic fact of human development-each forms within 12 weeks of conception from embryonic skin. The embryo's outer surface, or ectoderm, develops into hair, nails, skin glands, nervous system, and sensory organs.

Anhidrotic ectodermal dysplasia, which means abnormal growth of the ectoderm, including an inability to sweat, appears mainly in men. "It is remarkable that no instance has occurred of a daughter being thus affected," Darwin noted in his report on the Indian family.

Such an inheritance pattern had long indicated to scientists that the genetic flaw responsible for the disorder is located on the X chromosome. Women have two copies of the X chromosome, so one normal copy can compensate for a faulty one. Men have only one X chromosome, so they cannot escape the consequences of an error.

Srivastava's team began its quest for the gene with a woman who had the disorder. …

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