NUCCA News - Scientists map genes linked to Alzheimer's

Agence France-Presse

http://www.canada.com/health/story.html?id=%7B244C8DFA-561D-46C4-95BA-D6AFF263FD1E%7D

Thursday, January 02, 2003

PARIS -- An international consortium of researchers say they have decrypted a chromosome occurring in a broad range of disorders, including a brutal form of Alzheimer's that can strike people in their 30s.

Chromosome 14 -- the fourth chromosome to be fully sequenced -- comprises 87,410,661 base pairs, which are the "rungs" that make up the ladder of DNA, the chemical recipe for making a human being.

The sequence comprises 1,050 genes and gene fragments, according to the research published today in the weekly British science journal Nature.

Gene scientists have already published a draft of the human genetic code, or genome, providing a goldmine of raw material that now has to be refined and analyzed before it can be exploited.

Groups are working through one chromosome after another, weeding out flaws and inconsistencies in the data and notably identifying the genes, the machinery for making proteins -- the compounds that virtually make up all of the body and maintain it.

The goal behind this is to provide diagnostic tools that can spot flawed genes that cause illness, and ultimately to provide treatments which stop these genes from malfunctioning.

The consortium, led by Roland Heilig and Jean Weissenbach of the French gene research centre Genoscope, say chromosome 14 has two clusters of genes which are vital for the functioning of the immune system, as well as more than 60 disease genes.

The chromosome has already been identified in previous studies with a very wide range of diseases, including a form of spastic paraplegia that strikes young children; missing teeth, a condition called oligodontia; several kinds of vision and hearing impairments; and early onset Alzheimer's, the term for Alzheimer's disease that occurs before 60 and even among people in their 30s.

Around 200,000 North Americans have early onset Alzheimer's disease, accounting for five per cent of the four million people with Alzheimer's.

Human beings have 23 sets of chromosomes. Three other chromosomes have been fully sequenced in the past three years: 20, 21 and 22.