Science AMA Series: We are Hakhamanesh Mostafavi, Molly Przeworski, and
Joe Pickrell, authors of a recent paper using large DNA databases to
identify the ways human populations continue to evolve. AUA!
Abstract
Hello Reddit! We are: Hakhamanesh Mostafavi: Graduate student in biology
at Columbia University Molly Przeworski: Professor of biology at
Columbia University Joe Pickrell: CEO at personal genomics company
Gencove and professor at the New York Genome Center. We are a few of the
authors of a recent paper Identifying genetic variants that affect
viability in large cohorts where we sought to use biomedical data sets
to learn about mutations that affect survival. This paper was covered in
a number of news outlets with titles like Massive genetic study shows
how humans are evolving, and there was a great discussion of the paper
on r/science What does it mean for humans to still be evolving? For a
species to evolve simply means that mutations—the accidental changes
to the genome that happen in the process of copying DNA—are increasing
or decreasing in frequency in the population over time. Our basic idea
was that mutations that affect the chance of survival should be present
at lower frequency in older individuals. For example, if a mutation
becomes harmful at the age of 60 years, people who carry it have a lower
chance to survive past 60, and so the mutation should be less common
among those who do. We therefore looked for mutations that change in
frequency with age among around 60,000 individuals from California (as
part of the GERA cohort) and around 150,000 from the UK Biobank. Across
the genome, we found two variants that endanger survival in these
individuals: (i) a mutation in the APOE gene, which is a well-known risk
factor for Alzheimer’s disease, drops in frequency beyond age 70, and
(ii) a mutation in the CHRNA3 gene, associated with heavy smoking,
starts to decrease in frequency at middle-age in men.We found genetic
mutations linked to a number of diseases and metabolic traits to be
associated with survival: individuals who are genetically predisposed to
have highertotal cholesterol, LDL cholesterol, risk of heart disease,
BMI, risk of asthma, or lower HDL cholesterol, tend to die younger than
others. Perhaps more surprisingly, we discovered that people who carry
mutations that delay puberty or the age at which they have their first
child tend to live longer. Thanks for having us, this was a lot of fun