Gene mapping

A more direct approach to locating and identifying genes involved in psychiatric disorders is to attempt to map them. Gene mapping technology has advanced at an astonishing pace over the past 20 years. Early studies in psychiatric disorders such as schizophrenia (H) had to rely purely on 'classical' genetic markers such as HLA antigens blood groups and various protein polymorphisms. Capabilities in systematic gene mapping, which involves mounting a search throughout the whole genome (i.e. the 22 pairs of autosomes and the sex chromosomes), only became possible after the discovery of markers based on variation in DNA length. The first of these were the restriction fragment length polymorphisms and these have largely been supplanted by simple sequence repeat polymorphisms such as dinucleotide repeat polymorphisms. There is now a very detailed 'reference map' of the genome based on several thousand, more or less evenly spaced dinucleotide repeats. We can look forward to an even better map within the next few years, with the Human Genome Project on course to sequence the human genome before its target date of 2003 and the introduction of tens of thousands of new marker maps based upon single nucleotide polymorphisms. Such marker maps allow the genes contributing to traits or diseases to be located which is the first stage in positional cloning in which the genes themselves are then identified. The methods for mapping are linkage and association. Gene mapping is discussed further in Chapter2.4...2..

Funny Wiring Autism

Funny Wiring Autism

Autism is a developmental disorder that manifests itself in early childhood and affects the functioning of the brain, primarily in the areas of social interaction and communication. Children with autism look like other children but do not play or behave like other children. They must struggle daily to cope and connect with the world around them.

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