In genomic analyses from 23andMe is suggesting that uniparental disomy (UPD)—inheriting two copies of a chromosome from either your mother or father—is more common than researchers previously thought. It is usually identified in the context of disease but this new study from 23andMe suggest otherwise, and is found in healthy people as well. The data from this research suggests that UPD occurs in about ever 1 in 2,000 people.
The analysis used 4.5 million 23andMe customers and 430,000 people from the Biobank in the United Kingdom. Analyzing this data, they found that UPD can affect nearly all of the chromosomes, including sex chromosomes. UPD was identified in this data using a technique they developed to compare homozygosity between chromosome pairs.
The researchers were able to link some traits with specific UPD chromosomes. For example, have two copies of chromosome 6 from one parent was associated with lower body weight, while the same with chromosome 22 was associated with a higher risk of autism. Contrary to belief, the study showed that UPD (for the most part) was not associated with any harmful phenotypes.