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PEX7 gene

Reviewed by Medicinsk Expert•Last updated: 2026-10-22•Gene

PEX7 gene

The PEX7 gene provides instructions for a protein that transports essential enzymes into peroxisomes, which are vital for lipid production and the breakdown of fatty acids.

Normal Function

The PEX7 gene provides instructions for making a protein called peroxisomal biogenesis factor 7, which is part of the peroxisomal assembly (PEX) proteins. These proteins are responsible for importing enzymes into peroxisomes. These enzymes are critical for:

  • Breaking down fatty acids and toxic compounds.
  • Producing lipids used in digestion and the nervous system.

Peroxisomal biogenesis factor 7 transports enzymes such as alkylglycerone phosphate synthase (required for the synthesis of plasmalogens) and phytanoyl-CoA hydroxylase (which helps process phytanic acid).

Health Conditions Related to Genetic Changes

Refsum disease

Mutations in the PEX7 gene cause a small percentage of cases of Refsum disease. These mutations reduce the activity of peroxisomal biogenesis factor 7, disrupting the import of enzymes like phytanoyl-CoA hydroxylase. Consequently, phytanic acid cannot be broken down and builds up in body tissues, becoming toxic over time.

Rhizomelic chondrodysplasia punctata

More than three dozen mutations in the PEX7 gene cause rhizomelic chondrodysplasia punctata type 1 (RCDP1). These mutations are typically more severe than those causing Refsum disease, often resulting in a completely nonfunctional protein or preventing its production entirely. A common mutation, Leu292Ter (L292X), introduces a premature stop signal. These mutations prevent the transport of alkylglycerone phosphate synthase, leading to a shortage of plasmalogens, which causes skeletal abnormalities and intellectual disability.

Genomic Location

The PEX7 gene is found on chromosome 6.

Frequently Asked Questions

Key differences lie in clinical presentation and biochemical testing. Refsum disease typically presents in adolescence or adulthood with progressive retinitis pigmentosa, peripheral neuropathy, and elevated plasma phytanic acid, but normal skeletal development. RCDP1 presents in infancy with severe shortening of the proximal limbs (rhizomelia), facial dysmorphism, cataracts, and markedly low plasmalogen levels. Genetic testing that identifies the specific PEX7 mutation (e.g., missense vs. nonsense) also helps distinguish the two.
Currently, treatment is mainly supportive: early physical and occupational therapy to maximize mobility, cataract surgery when indicated, and nutritional support to address feeding difficulties. Experimental approaches such as plasmalogen replacement therapy are under investigation but not yet standard care. Participation in clinical trials, when available, may provide access to emerging treatments.
Since Refsum disease and RCDP1 are autosomal recessive, each pregnancy has a 25 % chance of an affected child if both parents are carriers. Options include: (1) natural conception with prenatal diagnostic testing (chorionic villus sampling at 10‑12 weeks or amniocentesis at 15‑18 weeks) to detect PEX7 mutations; (2) preimplantation genetic testing for monogenic disorders (PGT‑M) with IVF to select embryos without pathogenic variants; (3) use of donor gametes if you wish to avoid the risk entirely. Genetic counseling is strongly recommended.
Phytanic acid is abundant in ruminant animal products and certain fish. Avoid or severely limit: whole‑fat dairy (milk, cheese, butter), beef, lamb, pork, and fatty fish such as cod liver oil, herring, and eel. Use plant‑based oils (olive, canola) and low‑phytanic protein sources (eggs, poultry, soy). Regular plasma phytanic acid monitoring guides how strict the restriction needs to be.
Source: MedlinePlus, National Library of Medicine

MedlinePlus brings together authoritative health information from the National Library of Medicine (NLM), the National Institutes of Health (NIH), and other government agencies and health-related organizations.