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TRAPPC2 gene
Reviewed by Medicinsk Expert•Last updated: 2026-10-22•Gene

TRAPPC2 gene

The TRAPPC2 gene produces the protein sedlin, which is vital for transporting proteins within cells; mutations in this gene cause X-linked spondyloepiphyseal dysplasia tarda.

Normal Function

The TRAPPC2 gene provides instructions for producing the protein sedlin, which is found in cells throughout the body. Sedlin is part of a large group of proteins called the trafficking protein particle (TRAPP) complex, which plays a role in the transport of proteins between cell compartments (organelles). Sedlin is thought to be located between two organelles, the endoplasmic reticulum and the Golgi apparatus. The endoplasmic reticulum is involved in protein processing and transport, and the Golgi apparatus modifies newly produced proteins.

Research shows that sedlin is required for transporting large proteins from the endoplasmic reticulum to the Golgi apparatus. For example, sedlin is needed to move large molecules called procollagens out of the endoplasmic reticulum so they can be processed further by the Golgi apparatus. Later, procollagens are altered by enzymes outside the cell to create smaller mature collagen proteins, which strengthen and support connective tissues, such as skin, bone, cartilage, tendons, and ligaments.

Health Conditions Related to Genetic Changes

X-linked spondyloepiphyseal dysplasia tarda

More than 50 mutations in the TRAPPC2 gene have been found to cause X-linked spondyloepiphyseal dysplasia tarda. This condition impairs bone growth and occurs almost exclusively in males, usually appearing between ages 6 and 10. Almost all mutations result in a nonfunctional sedlin protein. As a result, large proteins, including procollagen, cannot be transported out of the endoplasmic reticulum. A lack of procollagen transport reduces the amount of mature collagen in cells, which impairs the development of bones, cartilage, and other connective tissues. It is likely that this disruption in bone development leads to many of the signs and symptoms of X-linked spondyloepiphyseal dysplasia tarda.

Other Names for This Gene

  • MBP-1 interacting protein-2A
  • MIP-2A
  • SEDL
  • sedlin
  • SEDT
  • TPPC2_HUMAN
  • TRS20
  • ZNF547L

Frequently Asked Questions

Diagnosis begins with a detailed clinical history (short stature, disproportionate trunk, delayed puberty) and a focused physical exam. Radiographs of the spine and pelvis typically show flattened vertebral bodies and epiphyseal dysplasia of the long bones. If the imaging is suggestive, molecular testing of the TRAPPC2 gene is performed, usually by targeted next‑generation sequencing or Sanger sequencing of the coding exons. In some centers, a multigene panel for skeletal dysplasias is ordered first, which includes TRAPPC2. Confirmation of a pathogenic or likely‑pathogenic variant establishes the diagnosis.
Because TRAPPC2 is located on the X chromosome, females are typically carriers and are usually asymptomatic. However, skewed X‑inactivation can occasionally lead to mild skeletal anomalies, such as subtle short stature or joint laxity. Carrier testing is recommended for mothers, sisters, and maternal aunts of an affected male, especially if they are planning pregnancy. Testing is performed with a blood sample for DNA sequencing; results help guide reproductive counseling and allow identification of at‑risk male offspring.
There is no cure, but several interventions can mitigate complications. Regular monitoring of growth and spinal curvature with orthopedic follow‑up allows early detection of scoliosis or kyphosis, which may be treated with bracing or, rarely, surgery. Calcium and vitamin D supplementation, along with weight‑bearing exercise, support bone mineral density. Physical therapy focused on joint range‑of‑motion and low‑impact strengthening helps preserve mobility and reduces pain. In severe cases, growth hormone therapy has been tried, but evidence of benefit is limited and should be considered only in a clinical trial setting.
The most common early clues appear between ages 6 and 10 and include: (1) gradual slowing of growth velocity resulting in height below the 5th percentile, (2) mild lumbar lordosis or back pain, (3) disproportionate shortening of the trunk relative to the limbs, and (4) early onset of joint stiffness, especially in the hips and knees. A family history of affected male relatives or unexplained short stature in male cousins also raises suspicion. If two or more of these findings are present, referral to a pediatric orthopedic or genetics specialist is warranted.
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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