An analysis of over 5.4 million individuals has identified over 12,000 different genetic variants that affect human height.
This is one of the largest human genetic studies yet, more than seven times the size of previous studies looking at height. The research also revealed that the location of the identified variants within the genome is not random; they cluster within short DNA regions that make up 21 percent of the genome.
'We're now basically done mapping this heritability to specific genomic regions, and that highlights what increasing sample size can tell us about traits controlled by multiple genes,' said co-senior author Professor Joel Hirschhorn, professor of genetics at Harvard Medical School in Boston, Massachusetts.
The study, published in Nature, was a meta-analysis of 281 genome-wide association studies (GWAS) which examine whole genomes to identify genetic variants associated with phenotypic traits.
Of the 281 studies, 173 involved participants of predominantly European ancestry, and identified variants accounting for 40 percent of height differences within this group. The authors believe this sample size is large enough that they have found all variants affecting height in this population.
Fifty-six of the studies involved predominantly East Asian participants, 29 were predominantly African, 12 South Asian, and 11 studies involved individuals of Hispanic ethnicity, accounting for over a million genomes in total. However, even though this is a large number compared to previous studies, the variants identified in these groups account for only ten-20 percent of height differences. The authors acknowledge that more genomic data from these groups is needed.
'This feat marks a milestone in our understanding of the contribution of genetics to complex traits. It also highlights the essential work still to be done to close the diversity gap in existing genetic data,' Karoline Kuchenbaecker, professor of genetic epidemiology at University College London, who was not involved in the research, said.
The study also revealed that the identified DNA variants are likely to be located close to genes known to be involved in Mendelian growth disorders.
Height is a good model to study polygenic traits, because it is highly heritable and easy to measure. This model can serve as a foundation for further studies aiming to identify variants affecting complex multi-factorial health conditions, ultimately leading to targeted personalised medical care.
'If we can map specific parts of the genome to certain traits, it opens the door to widespread targeted, personalised treatments further down the line that could benefit people everywhere,' said co-first author Dr Eirini Marouli, senior lecturer in computational biology at Queen Mary University of London.
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