Genetic Revelations

PAGES ARE BEING ADDED TO THE BOOK OF GENETICS at an accelerating pace these days. Researchers announced that they have identified a defective gene that appears to cause amyotrophic lateral sclerosis, better known as Lou Gehrig's disease. About 30,000 Americans suffer from the disorder, which causes degeneration of the nerves that carry signals to muscles. The trouble in some cases, scientists reported in Nature, apparently lies in the gene that directs production of an enzyme that mops up free radicals. These substances are metabolism's nasty residue.

In the same journal, scientists revealed that multiple sclerosis, the crippling nervous-system disease, may be linked to white blood cells with a specific genetic rearrangement. These white cells seem to destroy the sheath that surrounds nerves and protects their ability to conduct messages.

As researchers are finding out how genes cause illness, they are also working on genetic cures. A federal panel approved a new trial of an experimental gene therapy for brain cancer. Doctors take a gene from the herpes virus and insert it into tumor cells. They then zap the cells with an antiviral drug that attacks the herpes gene -- and thus the tumor. (See related story on page 56.)