A multilocus genotype is the combination of

allele An allele is a variant of the sequence of nucleotides at a particular location, or Locus (genetics), locus, on a DNA molecule. Alleles can differ at a single position through Single-nucleotide polymorphism, single nucleotide polymorphisms (SNP), ...

s found at two or more loci in a single individual. For example, in a

diploid Ploidy () is the number of complete sets of chromosomes in a cell, and hence the number of possible alleles for autosomal and pseudoautosomal genes. Here ''sets of chromosomes'' refers to the number of maternal and paternal chromosome copies, ...

species, if there are two SNP loci and the first locus has alleles A and G, while the second locus has alleles T and C, the multilocus genotype can be represented as . If the genome is not haploid then the multilocus genotype does not necessarily determine which alleles co-occur on chromosomes. In the example, if the two loci are located on the same chromosome the possibilities are either or . Where A-T represents a

haplotype A haplotype (haploid genotype) is a group of alleles in an organism that are inherited together from a single parent. Many organisms contain genetic material (DNA) which is inherited from two parents. Normally these organisms have their DNA orga ...

with alleles A and T together on one chromosome and G and C together on the other. If the

haplotypes A haplotype (haploid genotype) is a group of alleles in an organism that are inherited together from a single parent. Many organisms contain genetic material (DNA) which is inherited from two parents. Normally these organisms have their DNA orga ...

are determined the multilocus genotype is referred to as a phased genotype, otherwise it is referred to as unphased. Some authors suggest that the term multilocus genotype should only be applied to phased multilocus data while others apply it to unphased multilocus data as well. The combination of alleles at two or more loci on a single chromosome make up a haplotype and the two haplotypes in a diploid individual make up the diplotype (a synonym for a phased multilocus genotype).

References

{{reflist Classical genetics Genetic genealogy