The DHH gene provides instructions for making a member of the hedgehog protein family. Hedgehog proteins are important for early development in many parts of the body. The protein produced from the DHH gene is believed to be involved in male sexual development and in the formation of the perineurium, the protective membrane around each bundle of fibers within a nerve.
DHH gene mutations have been identified in a small number of people with Swyer syndrome, a condition affecting sexual development also known as 46,XY complete gonadal dysgenesis or 46,XY pure gonadal dysgenesis. Affected individuals have two mutated copies of the DHH gene in each cell.
People usually have 46 chromosomes in each cell. Two of the 46 chromosomes, known as X and Y, are called sex chromosomes because they help determine whether a person will develop male or female sex characteristics. Girls and women typically have two X chromosomes (46,XX karyotype), and boys and men ordinarily have one X chromosome and one Y chromosome (46,XY karyotype).
Mutations in the DHH gene in people with Swyer syndrome affect the process of sexual differentiation, preventing affected individuals with a 46,XY karyotype from developing male gonads (testes) and causing them to develop female reproductive structures (a uterus and fallopian tubes).
DHH gene mutations have been identified in people with 46,XY disorder of sex development, also known as partial gonadal dysgenesis. These individuals have one mutated DHH gene in each cell. They may have external genitalia that do not look clearly male or clearly female (ambiguous genitalia) or other changes in the genitals and reproductive organs.
In addition to gonadal dysgenesis, some people with DHH mutations also have nerve abnormalities. These abnormalities affect nerves connecting the brain and spinal cord to muscles and sensory cells that detect sensations such as touch, pain, heat, and sound (the peripheral nervous system). Affected individuals may experience weakness and loss of sensation in their extremities (peripheral neuropathy).
- desert hedgehog homolog (Drosophila)