Novel alpha haemoglobin haplotypes in horses.

This research study is about identifying and describing four new types of haemoglobin (the molecule in red blood cells that carries oxygen) in horses that are different than the normal types. The authors also investigated the possible causes for these abnormalities.

Types of Novel Alpha Haemoglobin Haplotypes

• The researchers discovered four new haemoglobin haplotypes (variants) in horses, different from those typically found. Haplotypes are combinations of DNA sequences which are inherited together and occupy a specific area on a chromosome.
• The first two variants, known as AIIb and V, were determined to be copy number variants, meaning they contain different numbers of copies of a certain gene than usual. Typically, horses have two alpha genes; however, AIIb has only one, while V has three.
• The other two haplotypes, labelled AIIa and C, also have two alpha genes like normal. However, they produce identical, but variant-specific, globins (the protein part of haemoglobin) due to likely gene conversions.

Phenotypic Normal Horses and Aberrant Recombination

• The term “phenotypically normal” refers to horses that appear normal based on their physical traits and characteristics. But when examining their genetic makeup, the researchers found unusual configurations in two out of 60 such horses.
• These horses each had a triplicated rearrangement in the embryonic zeta-gene locus, meaning they had three copies of this gene sequence in their chromosomes rather than the typical number.
• The researchers speculate that each of the four variations was likely generated by erratic recombination events. Recombination is a process during the production of egg and sperm cells where sections of DNA are exchanged between two chromosomes, potentially leading to new combinations of gene sequences.