Haplotype

A haplotype is the genetic constitution of an individual with respect to one member of a pair of allelic genes. A haplotype can refer to only one locus or to an entire genome. A genome-wide haplotype would comprise half of a diploid genome, including one allele from each allelic gene pair.

A genotype is distinct from a haplotype because an individual's genotype may not uniquely define that individual's haplotype. As an example, consider two loci, each with two possible alleles, the first locus being either A or a, the second locus being B or b. If the genotype of an individual was found to be AaBb, there are two possible sets of haplotypes, corresponding to which pairs happen to occur on the same chromosome:

	haplotype at chromosome 1	haplotype at chromosome 2
haplotype set 1	AB	ab
haplotype set 2	Ab	aB

In this case, more information would be required to determine which particular set of haplotypes occur in the individual (i.e. which alleles appear on the same chromosome).

Haplotype

See also