Developments in Brief : Chromosome Mapping: Routes Could Lead to Hereditary-Disease Treatments

An emerging technique called chromosome mapping could lead to the deciphering of the human genetic code, and such information could help researchers understand and perhaps develop new treatments for many hereditary diseases.

“We’re learning things already that we couldn’t have anticipated,” Charles Cantor of Columbia University in New York said last week at the annual meeting of the American Assn. for the Advancement of Science in Chicago.

The mapping provides a rough guide to the location of various genes on the 23 pairs of human chromosomes, he said. “It looks thus far like the human genome (the full complement of genes) is a mosaic, sort of striped. It’s too early to know what this means, but we were very surprised to see any molecular pattern.”

Cantor speculated that the pattern, in which certain bands on the chromosomes are festooned with molecules called methyl groups and other bands are not, could indicate which genes are universally expressed in the body and which genes govern specialized functions in certain classes of cells.

Chromosome mapping separates chromosomes, the fibrous structures that carry genes, into ordered fragments, each of which has a length of several hundred thousand nucleotides. Nucleotides are the fundamental building blocks of genes. The entire human genetic code is carried in genes organized into strings made up of about 3 billion nucleotides. The order of the building blocks, which come in different forms, is the code that carries hereditary information.