People carry on average one to two mutations that, if inherited from both parents, can cause severe genetic disorders or death before reaching reproductive age. According to scientists at the University of Chicago, we harbor 0.58 recessive lethal mutations on average.
Such research is important for understanding population risk. Many genetic disorders that result in reproductive problems or childhood death are caused by recessive mutations. These are DNA sequence variants that are harmless when a person carries only one copy. However, when these mutations are present at both copies (where one copy was inherited from each parent), they can cause serious diseases like cystic fibrosis (a genetic disorder that affects mostly the lungs but also the pancreas, liver, kidneys and intestine.)
By studying mutation rates within a population in South Dakota that has for generations kept detailed genealogical records, scientist Ziyue Gao has been able to calculate the average number of recessive lethal mutations each member of the group carries. Gao and his research team then extended its estimate to encompass a broader human population, and settled on a similar figure of around 0.58.
This number is on par with, or even slightly lower than, previous estimates. This latest estimate “is probably lower than the real average for most populations, but it is in the right ballpark,” Gao said in a research note.
Interestingly, the recessive disease mutation figure for people is similar to those of fruit flies and fish, even though these organisms all have different total genome sizes. This suggests a certain risk in most animal populations.
The findings have been published in the journal Genetics. The research is called “An Estimate of the Average Number of Recessive Lethal Mutations Carried by Humans.”
