Definitions for "HAPLOGROUP"
A haplotype that is defined by binary markers, which is more stable but less detailed than one defined by microsatellites.
Haplogroups are large groups that can be used to define genetic populations and are often geographically orientated. For example, when the Y-chromosome is tested, many males who live along the western coasts of Europe belong to Haplogroup R1b (used to be called HG1), which belies the historical movement of males along that coast. One way to think about haplogroups is that a haplogroup is a branch on the tree of Homo Sapiens and a haplotype represents the leaves of the tree. All the haplotypes that belong to a haplogroup are leaves on the same branch. The Y-chromosome haplogroup of an individual is not defined by their haplotype (because haplotypes are determined by STR markers). Instead, they are determined by SNP's (single nucleotide polymorphisms) where a single base changes e.g. from A to G. These happen so rarely as to be considered unique. However, there is a strong correlation between haplogroups and haplotypes so given any particular haplotype, it may be possible to correctly determine the haplogroup without any further tests.
a classification comprising many different haplotypes thought to be related. Haplogroups are defined in terms of markers that mutate so slowly they are treated as if they have occurred only once in all time. Therefore, the major haplogroups originated thousands or tens of thousands of years ago.