Cataracts, osteoporosis, heart disease, and other such ills typically afflict only the aged. For the unfortunate sufferers of a disease called Werner’s syndrome, however, these ailments strike not in the seventh or eighth decade of life but the third. Such people age abnormally fast and usually die before they reach 50.
Recently, molecular geneticist Gerard Schellenberg and his colleagues at the Veterans Affairs Medical Center in Seattle traced the gene that causes the disease to a site on chromosome 8. When they then compared the gene’s dna sequence with those of previously identified genes, they found that it closely matched genes known to code for a class of enzymes called helicases, which unwind the double helix of dna.
Helicases--of which there are many different types--are crucial components of all living cells. They help repair dna and enable messenger rna molecules to ferry genetic instructions from the nucleus, where dna resides, ...
