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

PEPD gene

The PEPD gene provides instructions for making the enzyme prolidase, which is essential for breaking down certain proteins and recycling amino acids in the body.

Normal Function

The PEPD gene provides instructions for making the enzyme prolidase, also called peptidase D. Prolidase helps divide certain dipeptides, which are molecules composed of two protein building blocks (amino acids). Specifically, prolidase divides dipeptides containing the amino acids proline or hydroxyproline. By freeing these amino acids, prolidase helps make them available for use in producing proteins that the body needs.

Prolidase is also involved in the final step of the breakdown of some proteins obtained through the diet and proteins that are no longer needed in the body. Prolidase is particularly important in the breakdown of collagens, a family of proteins that are rich in proline and hydroxyproline. Collagens are an important part of the extracellular matrix, which is the lattice of proteins and other molecules outside the cell. The extracellular matrix strengthens and supports connective tissues, such as skin, bone, cartilage, tendons, and ligaments. Collagen breakdown occurs during the maintenance (remodeling) of the extracellular matrix.

Health Conditions Related to Genetic Changes

Prolidase deficiency

At least 19 mutations in the PEPD gene have been identified in people with prolidase deficiency, a disorder with a wide variety of signs and symptoms including skin problems and intellectual disability. The PEPD gene mutations identified in people with prolidase deficiency result in the loss of prolidase enzyme activity.

It is not well understood how the absence of prolidase activity results in the various signs and symptoms of prolidase deficiency. Researchers have suggested the following possibilities:

  • Cell death: Accumulation of dipeptides that have not been broken down may lead to cell death. When cells die, their contents are released into the surrounding tissue, which could cause inflammation and lead to the skin problems seen in the condition.
  • Impaired collagen breakdown: Problems with the remodeling of the extracellular matrix may contribute to skin issues.
  • Neuropeptide processing: The intellectual disability that occurs in prolidase deficiency might result from problems in processing neuropeptides, which are brain signaling proteins that are rich in proline.

Other Names for This Gene

  • aminoacyl-L-proline hydrolase
  • imidodipeptidase
  • MGC10905
  • PEPD_HUMAN
  • PROLIDASE
  • proline dipeptidase
  • X-Pro dipeptidase
  • xaa-Pro dipeptidase

Frequently Asked Questions

Infants with prolidase deficiency often develop skin lesions such as recurrent ulcerations, especially on the lower limbs, and may have delayed wound healing. They may also show mild developmental delays or intellectual disability, and some children experience joint pain or swelling. Early dermatologic evaluation and developmental screening can help identify these issues before they become severe.
Prolidase deficiency follows an autosomal recessive inheritance pattern. If both parents carry a pathogenic PEPD mutation, each pregnancy has a 25 % chance of producing an affected child, a 50 % chance of a carrier, and a 25 % chance of being unaffected. Genetic counseling and carrier testing are recommended for families with a known mutation.
Diagnosis typically involves a combination of clinical assessment, biochemical testing for elevated plasma dipeptides (especially proline‑containing dipeptides), and genetic sequencing of the PEPD gene to identify pathogenic mutations. A skin biopsy can also show characteristic histological changes, and enzyme activity assays can directly measure prolidase function.
Management is largely supportive: regular wound care with moist dressings, infection prevention, and use of topical or systemic antibiotics if needed. Pain can be managed with NSAIDs or other analgesics. Some clinicians use amino‑acid supplementation (e.g., proline) or collagen‑based dressings to promote healing, though evidence is limited. Physical therapy may help maintain joint mobility.
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.

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