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. Author manuscript; available in PMC: 2012 Apr 1.
Published in final edited form as: Ageing Res Rev. 2010 Aug 10;10(2):191–200. doi: 10.1016/j.arr.2010.07.005

Figure 1.

Figure 1

Diagrammatic representation of the hypothetical transmission of a genetic variant influencing lifespan from a distant relative, as well as chromosomal markers flanking the variant. Solid lines denote exact generational links, whereas dotted lines denote lines of descent involving a large number of generations. Shaded pedigree members have a specific lifespan phenotype. Vertical rectangles next to pedigree member symbols reflect a single chromosome and letters next to the rectangle reflect nucleotides at SNP loci. Shading within the rectangles indicates chromosomal material from the founder (denoted by the number 1) who introduced the life span-influencing nucleotide variation `T' into the population. This founder had `A' nucleotides at SNP positions flanking the site of the life span-influencing locus. The entire founder haplotype `A-T-A' was preserved during transmission to individual 2. However, recombination events during meioses in individuals with the line of descent from individual 1 to individuals 5 and 6 caused individuals 5 and 6 to only inherit the `T' allele associated with the life span-influencing phenotype. Due to a recombination event in the line of descent from individual 2 to the father in nuclear family 3, the father in nuclear family 3 only inherited the `A-T' haplotype encompassing the 1st two markers from ancestor 2 but not the ancestral founder allele `A' at the third locus. However, this `A-T' haplotype was preserved in the transmission of the chromosome harboring the `T' life span-influencing variant to two offspring in the nuclear family. The father in nuclear family 5 inherited the entire founder `A-T-A' haplotype and transmitted it in its entirely to one of his offspring due to a lack of recombination. Thus, although two siblings share part (`A-T') of the ancestral founder chromosomal haplotype harboring the `T' life span-influencing nucleotide (`A-T-A'), and an offspring in nuclear family 4 inherited the entire `A-T-A' haplotype, all the individuals in the latest generation with the life span phenotype only share the `T' ancestral functional nucleotide inherited from individual 1.