A gene family is a collection of genes that have similar characteristics. Because of ancestral duplications, gene families exist; what started out as one gene became many, which moved around in the genome and diverged from each other. Gene families can reveal a wealth of information about genetic inheritance and an organism’s history, making them a popular topic among geneticists, biologists, and others interested in biology and inheritance.
Gene families have nucleotide sequences that are similar, indicating that they share a common ancestor. The major histocompatibility complex, for example, is a large and diverse gene family that determines which antigens will be present on the surface of cells. A gene family’s members can work together to control the expression of a trait, whether it’s a bodily function or a physical feature, such as a cat’s calico coat.
Members of a gene family can be found in a variety of places, including different loci on different chromosomes and even on different chromosomes. It’s also possible to see a multigene family, or superfamily, of genes that aren’t all that similar but share some key motifs that reveal their common ancestry. Because these gene families are typically very old, they are sometimes used to determine when various genetic divergences occurred.
Researchers classify genes according to the DNA they contain and the functions they code for. People struggling to understand a particular genetic condition might gain new insight if they realized which gene family was involved if they organized into families. Similarly, being able to group genes into families can help people figure out what they do, because it’s possible to tell if a gene belongs to a family without knowing what it does.
Gene families can also be used to learn about genetic inheritance. Researchers can see how divergences occurred by comparing genetic information from related members of the same species with unrelated members, and they can sometimes use this data to figure out when they happened. This data can be used to investigate a species’ history by looking for traits that may have developed in response to changes in the environment or other factors. People can count backward through the genome to see when changes occurred because changes in the genome tend to occur at a constant rate.