The normal human genome

Understanding the human genome is essential for nutritionists.
1. Because the genome is biologically important
2. The genome is the basis for an individual person’s metabolism
3. The exciting innovations in nutrition will be throughan undersanding of the interplay between
dietary intake and genome constitution
Of importance are two articles in Nature 23rd November 2006.
Pages 428-429 ; 444-454
The human genome contains many forms of genetic variation. The most plentiful are the millions of single base-pair changes in the DNA code . This single nucleotide polymorphism (SNPs) distinguish any two unrelated copies of the genome. This forms the neutral forms of widespread genetic variation marking diversity between individuals in a species.
There are however variations in copy number of sequence elements that is in the number of deleted or duplicated versions or segments of the genome that result in a range of the number of copies among normal members of the population. These are called copy number variants ( CNVs). In a large study of various apparently normal individuals nearly 1500 variable regions involving nearly 12% of the human genome and including hundreds of genes and the copy number were shown to differ quite significantly.
This implies that genetic diversity lies not in the millions of SNPs but in larger segments of the genome.
The deletions or duplications might be expected to influence the protein production from that gene. Hence variation in proteins eg Haemoglobin.
Only when there is a full atlas of CNV variation and the consequences in terms of individual susceptibility to disease or nutritional metabilism will these variations have any meaning.

Martin Eastwood
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