PAX gene family

The PAX gene family plays a critical role in the formation of tissues and organs during embryonic development. The PAX gene family is also important for maintaining the normal function of certain cells after birth. To carry out these roles, the PAX genes provide instructions for making proteins that attach to specific areas of DNA and help control the activity (expression) of particular genes. On the basis of this action, PAX proteins are called transcription factors.

After birth, the PAX genes are usually turned off (inactivated), but in some tissues the PAX genes are active. These active genes aid in tissue re-growth and protect against cell death caused by cellular stress (such as increased sodium levels in the cell).

There are nine genes in the PAX gene family. These genes are divided into subgroups based on various aspects of similarity. Subgroup I includes PAX1 and PAX9; subgroup II includes PAX2, PAX5, and PAX8; subgroup III includes PAX3 and PAX7; and subgroup IV includes PAX4 and PAX6.

Mutations in PAX genes lead to disorders that involve the incomplete development of tissues in which a particular PAX gene is expressed. Additionally, the overexpression of PAX genes has been noted in a variety of cancers. It is thought that the cell protection function of PAX genes prevents cell death and permits tumor growth (proliferation).