<unk> S can be used to identify five European "clusters" In population genetics, an<unk>  <unk>  is a single-nucleotide polymorphism that exhibits substantially different frequencies between different populations. A set of many<unk> s can be used to estimate the proportion of<unk>  of an individual derived from each population. A single-nucleotide polymorphism is a modification of a single nucleotide base within a DNA sequence. There are an estimated 15 million SNP (Single-nucleotide polymorphism) sites (out of roughly 3 billion base pairs, or about 0.4%) from among which<unk> s may potentially be selected. The SNPs that relate to<unk>  are often traced to the Y chromosome and mitochondrial DNA because both of these areas are inherited from one parent, eradicating complexities that come with parental gene recombination. SNP mutations are rare, so sequences with SNPs tend to be passed down through generations rather than altered each generation. However, because any given SNP is relatively common in a population, analysts must examine groups of SNPs (otherwise known as<unk> S) to determine someone's<unk> . Using statistical methods such as apparent error rate and Improved Bayesian Estimate, the set of SNPs with the highest accuracy for predicting a specific<unk>  can be found. Examining a suite of these markers more or less evenly spaced across the genome is also a cost-effective way to discover novel genes underlying complex diseases in a technique called admixture mapping or mapping by admixture linkage disequilibrium. As one example, the Duffy Null allele (FY*0) has a frequency of almost 100% of Sub-Saharan Africans, but occurs very infrequently in populations outside of this region. A person having this allele is thus more likely to have Sub-Saharan African ancestors. North and South Han Chinese<unk>  can be distinguished unambiguously using a set of 140<unk> S. Collections of<unk> s have been developed that can estimate the geographical origins of ancestors from within Europe. Following the development of ancient DNA databases, ancient<unk>  (aAIM) were similarly defined as a single-nucleotide polymorphism that exhibits substantially different frequencies between different ancient populations. A set of aAIMs can be used to identify the<unk>  of ancient populations and eventually quantify the genetic similarity to modern-day individuals.
Ancestry-informative marker
Predictive marker
Replication error phenotype
Human disease modifier gene
Risk of mortality
Genetic discrimination
Natural history of disease
Genetic heterogeneity