CD55 encodes CD55 molecule (Cromer blood group) (381 aa). This protein recognizes C4b and C3b fragments that condense with cell-surface hydroxyl or amino groups when nascent C4b and C3b are locally generated during C4 and c3 activation. Highest expression in Whole Blood (181.9 TPM) and Lung (169.8 TPM).

Protein-losing enteropathy is associated with mutations in the CD55 gene on chromosome 1.

The CD55 protein participates in CD55 (DAF) promotes C3bBb/C4bC2a dissociation and CD59 inhibits MAC formation pathways.

CD55 is classified as a druggable target (Cell Surface and Druggable Genome categories) with score 10.4.

Genetic testing for CD55 is available. Testing is considered confirmatory for diagnosis.

Biomarker and diagnostic research for protein-losing enteropathy has been reported in the published literature.

No approved treatments are currently available for protein-losing enteropathy. An additional 1 compound holds orphan drug designation.

Orphan Drug Designations

While no drugs are FDA-approved specifically for protein-losing enteropathy, some of the following designated compounds may be used off-label in clinical practice. Treatment decisions should be made in consultation with a specialist familiar with this condition.

The following drugs have received orphan drug designation from the FDA for protein-losing enteropathy. Orphan designation reflects regulatory interest and does not indicate approval for treatment.

Gene therapy approaches for protein-losing enteropathy have been reported in the published literature.

Phenotype severity distribution: 2 always present features, 3 very common features, 7 common features.

Estimated prevalence: <1 in 1,000,000 (VERY_RARE).

1 clinical trial registered, 1 recruiting. Interventions under study include drug therapy. Pipeline includes 1 PHASE4. Research is primarily industry-sponsored.

217 publications have been identified in PubMed for protein-losing enteropathy. Research spans Case Report / Case Series (33%), Review / Meta-Analysis (21%), and Epidemiology / Natural History (14%).

Recent Publications

• Thomas J (2026). [PMID: 41937906](https://pubmed.ncbi.nlm.nih.gov/41937906/). *ACG case reports journal*. [Case Report / Case Series]

• Becking AL (2026). [PMID: 42069413](https://pubmed.ncbi.nlm.nih.gov/42069413/). *Lancet Haematol*. [Case Report / Case Series]

• Pultrone M (2026). [PMID: 41882644](https://pubmed.ncbi.nlm.nih.gov/41882644/). *BMC Vet Res*. [Epidemiology / Natural History]

• El Omeiri S (2026). [PMID: 41991350](https://pubmed.ncbi.nlm.nih.gov/41991350/). *Semin Roentgenol*. [Review / Meta-Analysis]

• Kowalczyk M (2026). [PMID: 42123271](https://pubmed.ncbi.nlm.nih.gov/42123271/). *J Clin Med*. [Review / Meta-Analysis]

• Marathe SP (2026). [PMID: 41548840](https://pubmed.ncbi.nlm.nih.gov/41548840/). *J Thorac Cardiovasc Surg*. [Case Report / Case Series]

• Schroeder C (2026). [PMID: 41644698](https://pubmed.ncbi.nlm.nih.gov/41644698/). *Scientific reports*. [Clinical Trial Publication]

• Jiang L (2026). [PMID: 42112145](https://pubmed.ncbi.nlm.nih.gov/42112145/). *Kidney Med*. [Case Report / Case Series]

• J RP (2026). [PMID: 41933582](https://pubmed.ncbi.nlm.nih.gov/41933582/). *Journal of thoracic oncology : official publication of the International Association for the Study of Lung Cancer*. [Basic Science / Preclinical]

• Moriwaki K (2026). [PMID: 41922227](https://pubmed.ncbi.nlm.nih.gov/41922227/). *Journal of clinical and experimental hematopathology : JCEH*. [Case Report / Case Series]