Science / Medicine : Finding Upsets Genetics Rule

A radical new finding that genes passed on by fathers may be different from those passed on by mothers may explain many puzzling cancers and inherited diseases, researchers announced last week. The finding contradicts one of the principles of modern genetics.

Dr. Judith Hall of the University of British Columbia in Canada said researchers are beginning to accept evidence that began to appear in the early 1980s suggesting that mothers and fathers each “imprint” genes with different signals before passing them on to their children. Scientists had previously thought that it made no difference to a child whether it inherited a genetic trait from its mother or its father, but were unable to explain nearly two-thirds of inherited diseases using this theory, Hall said.

For example, children have 23 pairs of chromosomes and normally get one set from each parent, Hall said. But children who mistakenly get two copies of chromosome 7 from their mother and no copy from their father can have severe growth retardation before and after birth. Conventional genetics says that should not happen--all that is needed is two good copies of the chromosome. But imprinting may help explain the fact that it does occur, Hall said. However, exactly how imprinting may lead to inherited disease remains unclear, she added.