These mutations in the PEX7 gene generally lead to rhizomelic chondrodysplasia punctata type 1, which impairs development of many parts of the body.

[citation needed] Histopathologic examination of the skin from a suspected patient commonly shows hyperkeratosis, hyper-granulosis and acanthosis.

The presence of cells in the basal and suprabasal layers of the epidermis containing variably sized vacuoles with accumulated lipids is pathognomonic for the disease.

[1][12] Since phytanic acid is not endogenously produced in the human body, individuals with Refsum disease are commonly placed on a phytanic-acid–restricted diet and avoid the consumption of fats from ruminant animals and certain fish, such as tuna, cod, and haddock.

[15] In ruminant animals, the gut fermentation of consumed plant materials liberates phytol, a constituent of chlorophyll, which is then converted to phytanic acid and stored in fats.

[18] Although humans cannot derive significant amounts of phytanic acid from the consumption of chlorophyll present in plant materials, it has been proposed that the great apes (chimpanzees, gorillas and orangutans) as well as other captive non-human primates can derive significant amounts of phytanic acid from the hindgut fermentation of plant materials.