Eihomologiset

Eihomologiset is a Finnish term used in biology to describe elements that lack homologous relationships. In cytogenetics, it often refers to chromosomes that are not a homologous pair because they do not carry the same genes in the same order, and thus do not pair during meiosis. More generally, the term can describe DNA sequences or genes that do not share a detectable evolutionary relationship, i.e., non-homologous sequences.

During meiosis, homologous chromosomes align and exchange genetic material through recombination. Non-homologous chromosomes typically do not pair, but rare exchanges between non-homologous partners can occur, leading to chromosomal rearrangements such as translocations, insertions, or deletions. In DNA repair, non-homologous end joining (NHEJ) is a pathway that joins broken ends without requiring long sequence homology and can generate eihomologous junctions.

Applications of the concept appear in karyotype analysis, comparative genomics, and discussions of gene families. The term emphasizes the lack of homology, distinguishing such elements from orthologs, paralogs, and xenologs. In practice, identifying non-homologous relationships helps researchers infer evolutionary history and detect structural variations.

Etymology and usage: The term derives from ei ("not") and homologiset ("homologous") in Finnish. In English-language texts, the equivalent term is non-homologous. The Finnish term is primarily used in Finnish-language scientific literature and education.