Segmentation gene

A segmentation gene is a gene involved in the early developmental stages of pattern formation. It regulates how cells are organized and defines repeated units in the embryo. Segmentation genes have been documented in three taxa: arthropods (i.e. insects and crabs), chordates (i.e. mammals and fish), and annelids (i.e. leeches and earthworms). In Drosophila melanogaster, a common fruit fly, segmentation genes divide the embryo into 14 parasegments which are among the first compartments to form within the embryo. Rare variants in segmentation genes can cause changes in appearance of differing severity depending on its type. The genes can be classified into 3 groups: Gap genes, Pair-rule genes and Segment polarity genes.