Expedition expansion: the first genetic reference map for tandem repeats
Researchers have built the first genetic reference map for tandem repeat expansions, a critical tool for congenital disease research.
Researchers at the University of California, Irvine (CA, USA) have recently built the first genetic reference map for repeated sequences of DNA found throughout the human genome, known as tandem repeats. This new reference map could help to improve our understanding of how these repeats are linked to disease.
Tandem repeat expansions – a type of mutation where short, repeated sections of DNA known as tandem repeats are longer than they’re supposed to be – have been linked to over 50 diseases. Our understanding of how these mutations contribute to congenital conditions like Huntington’s, however, is limited. This lack of understanding is compounded by the lack of diverse ancestries represented in reference sequences.
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The reference map built by the team at UC Irvine, called TR-gnomAD, specifically aims to help researchers determine how certain populations may be affected by certain diseases based on variations in tandem repeat expansions among ancestries.
“Genetic consulting companies can then develop products to interpret this information and accurately report how certain traits might be linked to different groups of people and diseases,” commented co-corresponding author, Wei Li.
The team used two software tools, ExpansionHunter and GangSTR, to map tandem repeats from the genomic data of 338,963 individuals across 11 sub-populations. A total of 0.86 million tandem repeats were analyzed.
Interestingly, their analysis showed that 30.5% of the tandem repeats had at least two variants that were common among ancestries.
The findings of this study offer a unique insight into the ancestry-specific prevalence of disease by identifying disparities among ancestries. They could also be used to identify potentially pathogenic tandem repeat expansions.
“Although we’ve successfully genotyped a substantial number of tandem repeats, that is still just a fraction of the total number in the human genome,” Li concluded. “Our next steps will be to prioritize the integration of a greater number of high-quality tandem repeats and include more underrepresented ancestries, such as Australian, Pacific Islander and Mongolian, as we move closer to realizing personalized precision medicine.”