When one thinks of health, we usually consciously or subconsciously associate that with life and death as the ultimate measurement of said health, age being the actual measurement. Doctors Peter Joshi and Jim Wilson out of the University of Edinburgh’s Usher Institute of Population Health have identified DNA alleles that may actually have an effect on the lifespan of a human. An allele is an alternative form of a gene that occurs due to mutation and occupies the same place (or locus) of a chromosome.
Women are affected by the APOE ε4 allele with an average effect of about -1.24 years of life whereas men are affected by a locus near the CHRNA 3/5 allele with an average effect of about -0.86 years per affected allele. About 0.3% of populations that have both (i.e. are homozygous for) the alleles at both loci are usually predicted to have about 3.3-3.7 years less of a lifespan. The research was done using data from the UK Biobank, using data from 22 centers between 2006 and 2010. Half a million subjects had their phenotypic information available, out of which only about a fifth had their genotype data. Also used in the study was data from The Estonian Biobank, located at the Estonian Genome Center at the University of Tartu.
The changes, known as variants, are actually pretty common. Over two thirds of us will inherit at least a single copy from either mother or father. Apolipoprotein E (APOE) is usually expressed most in the liver, brain and retina. The allele of this that’s associated with a bunch of age-related conditions including Alzheimer’s disease (APOE ε4) has a greater effect on women while the variant associated with lung disease (CHRNA 3/5) has a greater effect on men. CHRNA 5/3/4 locus encodes for nicotinic acetyl choline receptor subunits, and is thus susceptible to smoking, hence linked to lung cancers. Factors thus noted are that the adverse effects on lifespan of these two loci have been hidden from natural selection because of the modern risk of smoking and nicotine dependence (CHRNA 3/5) and the effect of APOE occurring well past the age of child bearing.Source: NATURE