Gene Hunting - Article Depression/depressive Disorders
Article: Gene Hunting
Many years of research have demonstrated that vulnerability to mental illnessesâ€”such as
Detecting multiple genes, each contributing only a small effect, requires large sample sizes and powerful technologies that can associate genetic variations with disease
Linkage studies are often based on the identification of large, densely affected families so that the inheritance patterns of known sections of DNA (called "markers") can be compared to the family's transmission of the disorder.
Linkage-disequilibrium studies in isolated populations capitalize on the likelihood that the susceptibility genes for a particular disorder probably came from one or a few founding members.
Association studies depend on the investigator hypothesizing that a specific gene or genes may influence the disorder. In this type of study, the investigator examines whether those people with the disorder have a different version of the gene than those without the disorder among related or unrelated individuals.
Evidence suggests that unaffected family members may share with their ill relatives genes that predispose for milder, but qualitatively similar behavioral characteristics. For example, some relatives of people with schizophrenia or autism may exhibit subtle cognitive problems.
Some gene variants are likely to turn on too much or too littleâ€”or in the wrong place. This could interfere with the way brain cells work. It may also affect how cells migrate to other parts of the brain and connect with one another during early development. NIMH has mounted an effort to vastly expand the set of available tools for discovering the molecular mistakes that produce mental illness.
A vital resource for doing this, now under development, will be a shared scientific infrastructure called the Brain Molecular Anatomy Project (BMAP). The goals of this multidisciplinary effort are to catalog the genes that are active in various parts of the brain at different developmental stages, and to make this information readily available to investigators on a Web-based map.
The mouse's brain is a major initial focus of BMAP. A Web-based digital mouse brain atlas will offer 3-D and 2-D views of this biological blueprint, covering different strains and ages of animals. In addition to advancing basic knowledge, the BMAP database promises to enhance clinical science, providing new leads for studying gene expression in post-mortem tissue, for the identification of candidate genes, and enhanced capacity to screen for individuals who might be at risk for developing brain disorders.
A related set of developing tools also centers on the mouse: identifying the neural basis of complex behaviors.
Chromosomes, visualized here, are long molecules of DNA, the genetic material.
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NIH Publication No. 01-4600
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Source: National Institute of Mental Health
Cache Date: December 16, 2004
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