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Of p's and q's and Chromobabble: Introduction to Gene Maps

Bandolier readers have already been subjected to chromobabble (in Bandolier 18 ). We apologise and offer what we hope is a simple guide to genetic geography, ie human gene maps.

The Human Genome Project will produce the ultimate map - the precise ordering and sequencing of the approximately 100,000 genes and 3x10 9 base pairs that make up the human genome. Currently (Nov 16th) the OMIM database (see Bandolier 21 ) has 4878 'solid' gene assignments and 2471 'potential or provisional' assignments.

Genetic geography

The first level of mapping is to assign genes to the chromosome regions defined by banding patterns seen after specific staining techniques (such as G banding with giemsa stain). As an example the banding patterns, with bands numbered and some gene assignments are given for chromosomes 1 and Y in the picture .
Numbering under the Paris convention is outwards from the chromomere, the short arm is designated p and the long arm q.

What is the significance of this? The point is that we now know where many genes are, we know what some of them do, we know their DNA sequence (sometimes) and most importantly we are beginning to understand how alterations in gene sequences can cause or influence disease.



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