PDE6H

Achromatopsia

At least one mutation in the PDE6H gene has been found to cause the vision disorder achromatopsia. It is a very rare cause of a form of the disorder called incomplete achromatopsia. This condition is characterized by limited color vision and other vision problems that are present from early infancy.

The identified mutation replaces one protein building block (amino acid) near the beginning of the inhibitory gamma subunit with a signal to stop protein production. This mutation is written as Ser12Ter or S12X. This change prevents the production of any functional inhibitory gamma subunit, which interferes with the normal function of cone-specific phosphodiesterase. Impairment of this enzyme disrupts the process of phototransduction in cones; rods are typically unaffected.

Because cones are needed for color vision, affected individuals have difficulty distinguishing certain colors. Their other vision problems are also related to the malfunctioning cones.