New approach estimates the average number of mutations per
person that cause disease when inherited from both parents. Humans carry an
average of one or more mutations per person that can cause severe genetic
disorders or prenatal death when two copies of the same mutation are inherited.
The numbers were found through long-term collaboration between medical
researchers and a unique community that has managed detailed family histories
for many generations.
DNA sequence variants are harmless when a person carries
only one copy but if both copies are present they can causes diseases such as
cystic fibrosis. Recessive disease mutations are much more harmful even if they
are only a single copy. The question is how common are the recessive
disease-causing mutations. Previous studies have been based off of parents that
have been related. However, this method mixes up the effects of genetics and
socioeconomic factors. In some places, marriage between close relatives
correlates with poverty. This is a bias because in these cases the children
have a higher disease and death rate due to poor nutrition or lack of medical
access.
New methods ignore the socioeconomic factors. To learn more
about recessive disease mutations, a large 13-generation family tree that
traces the ancestry of more than 1,500 living people was used. This was used to
come up with an estimate for the number of recessive disease mutations carried
by the group’s founders in the 18th and 19th century.
Using this information, it is estimated that there were around 3 mutations of
this type for every 5 people among the founders.
Surprisingly, the recessive disease mutation estimate for
humans is similar to those from fruit fly and fish species even though these organisms
have a different total genome size.
Article Used: http://www.genetics-gsa.org/media/releases/GSA_PR_2015_04_recessive_mutations.html
Related Article: http://www.sciencedaily.com/releases/2015/04/150408100522.htm
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