Ortholog

An ortholog is a gene in different species that evolved from a common ancestral gene through speciation. Orthologs typically retain the same function in the different organisms. Identification of orthologs helps to understand evolutionary relationships and predict the function of genes in newly sequenced genomes. Their conservation across diverse species makes them valuable for comparative genomics and drug target identification. Understanding the differences between orthologs is crucial for a complete evolutionary analysis.

Ortholog meaning with examples

• Scientists compared the genomes of humans and chimpanzees to identify orthologs. The researchers looked for genes in both species that shared a high degree of sequence similarity, suggesting they were orthologs derived from a common ancestor. These shared genes are vital for understanding the genetic basis of similarities and differences between the two primates. Their conservation offers insight into the genetic underpinnings of primate evolution.
• Studying the *BRCA1* gene, a well-known human gene, showed its ortholog in mice is also involved in DNA repair. The analysis helped scientists infer the gene's function. The observation validated the usefulness of this gene as a model for research. The identification of this ortholog allowed scientists to use mouse models to investigate potential treatments for breast and ovarian cancer.
• The pharmaceutical company researched the ortholog of a specific bacterial gene in several pathogenic strains to discover a new antibacterial agent. They reasoned that if the gene's function was conserved, inhibiting it would likely lead to a similar effect across multiple bacteria species. The development of an antibiotic targeting this specific ortholog could be highly effective. This comparative genomic strategy speeds up drug discovery.
• Researchers used orthologs in model organisms like *Drosophila* and *C. elegans* to study developmental processes. The identification of the orthologs of a specific human developmental gene in these model organisms enabled researchers to carry out detailed studies. These studies offered the ability to manipulate genes with higher efficiency and to test drug targets. The conservation of function made findings applicable to humans.