Image Caption: A triangle plot showing the clustering of 210 unrelated HapMap individuals assuming three ancestral populations (k = 3). The proximity of an individual to each apex of the triangle indicates the proportion of that genome that is estimated to have ancestry in each of the three inferred ancestral populations. The clustering together of most individuals from the same population near a common apex indicates the clear discrimination between populations obtained through this analysis. The clustering was qualitatively similar to that obtained previously with a similar number of biallelic Alu insertion polymorphisms on different African, European and Asian population samples.In a series of ongoing research projects, scientists have unearthed evidence that human phenotypes may be influenced by repeated sequences of DNA in addition to the traditional idea of genetic heritage.
A paper published in Nature (23rd of November, 2006) reported the investigation of various affects of differences in the numbers of repeats in sections of DNA, or copy number variations (CNVs), on the genotypes of humans. It states that CNVs are present in all humans and other mammals, and are known in Drosophila melanogaster (an example is the Bar gene causing the Bar eye phenotype).
In humans, the repeats have quite varied effects: the diseases Alzheimer’s and Parkinson’s, both being debilitating and incurable diseases which place great strain on our heath care system, are strongly linked to CNVs. On the other hand, genomes from Africans that were surveyed included numerous repeats in the CCL3L1 gene—greater numbers of repeats giving resistance to HIV-1 infection. Genomes from Asians families included repeats in DNA that may be linked to age-related cataracts and other heritable diseases. If you’re thinking that these varied bits of information on racial genetics suggest something important, you’d be right: CNV analysis has reinforced the idea of diversity in human continental populations! This means that CNV analysis can be used to determine and find the differences between Europeans, Africans and Asians genetically (as in this study’s case)—allowing the investigation of ethnicity and common ancestry in modern human populations, a crucial tool for disease and phenotype analysis in the modern world’s complex assortment of globalised genetics. The specific patterns of CNVs discovered in each population group suggest also that CNV occurrence is influenced by environment (such as the aforementioned HIV resistance in the African gene example). Interestingly, CNVs were found to only rarely occur in ultra-conserved sequences and gene sequences—compared with the common occurrence of conserved non-coding sections and putatively functional genes within CNV regions.
The study also found that CNPs occur in many genes that are already known to cause complex diseases, as well as in genes that are linked to complex traits. It certainly seems that human genetic study has to come a long way before even simple mechanisms such as repeated sequences can be understood.
Article found at: http://www.nature.com/doifinder/10.1038/nature05329
Accessed: 18/5/2009. The paper is available for viewing at this site, and it includes diagrams, references and much greater detail than this summary. Various other related articles may be found by following the links on this page. Also, the webpage of one of the teams involved in the 2006 paper can be found at http://www.sanger.ac.uk/Teams/Team16/ (as of 18/5/2009), and lists many additional papers that have been published from research in a similar vein to this topic.
A paper published in Nature (23rd of November, 2006) reported the investigation of various affects of differences in the numbers of repeats in sections of DNA, or copy number variations (CNVs), on the genotypes of humans. It states that CNVs are present in all humans and other mammals, and are known in Drosophila melanogaster (an example is the Bar gene causing the Bar eye phenotype).
In humans, the repeats have quite varied effects: the diseases Alzheimer’s and Parkinson’s, both being debilitating and incurable diseases which place great strain on our heath care system, are strongly linked to CNVs. On the other hand, genomes from Africans that were surveyed included numerous repeats in the CCL3L1 gene—greater numbers of repeats giving resistance to HIV-1 infection. Genomes from Asians families included repeats in DNA that may be linked to age-related cataracts and other heritable diseases. If you’re thinking that these varied bits of information on racial genetics suggest something important, you’d be right: CNV analysis has reinforced the idea of diversity in human continental populations! This means that CNV analysis can be used to determine and find the differences between Europeans, Africans and Asians genetically (as in this study’s case)—allowing the investigation of ethnicity and common ancestry in modern human populations, a crucial tool for disease and phenotype analysis in the modern world’s complex assortment of globalised genetics. The specific patterns of CNVs discovered in each population group suggest also that CNV occurrence is influenced by environment (such as the aforementioned HIV resistance in the African gene example). Interestingly, CNVs were found to only rarely occur in ultra-conserved sequences and gene sequences—compared with the common occurrence of conserved non-coding sections and putatively functional genes within CNV regions.
The study also found that CNPs occur in many genes that are already known to cause complex diseases, as well as in genes that are linked to complex traits. It certainly seems that human genetic study has to come a long way before even simple mechanisms such as repeated sequences can be understood.
Article found at: http://www.nature.com/doifinder/10.1038/nature05329
Accessed: 18/5/2009. The paper is available for viewing at this site, and it includes diagrams, references and much greater detail than this summary. Various other related articles may be found by following the links on this page. Also, the webpage of one of the teams involved in the 2006 paper can be found at http://www.sanger.ac.uk/Teams/Team16/ (as of 18/5/2009), and lists many additional papers that have been published from research in a similar vein to this topic.
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