What is prolidase deficiency?
Prolidase deficiency is sometimes called hyperimidodipeptiduria, imidodipeptidase deficiency or peptidase deficiency. It is a very rare hereditary disorder of collagen metabolism that leads to skin fragility and recurrent ulceration.
What are the clinical features of prolidase deficiency?
Features of prolidase deficiency include:
- Skin ulceration and fragility especially of the lower extremity
- Recurrent infections of the skin (including abscesses and folliculitis (pustules))
- Telangiectasia (dilated capillaries)
- Photosensitivity (skin sensitivity to sunlight)
- Hirsutism (increased hair growth)
- Occasionally, developmental delay or learning disability
- Characteristic facial features (saddle nose, small chin, jaw protrusion, widely spaced eyes)
- Respiratory tract infections, such as chest infections, and sinusitis
- Enlarged liver or spleen
- About 10% have systemic lupus erythematosus or a lupus-like illness
Who gets prolidase deficiency?
Prolidase deficiency occurs in approximately 1 in 1 million to 1 in 2 million newborns. It is due to a mutation in theprolidase gene (PEPD). This is located on chromosome 19 and encodes the prolidase enzyme that uses proline (an amino acid) for collagen synthesis.
Prolidase deficiency is inherited in an autosomal recessive pattern. This means that both copies of the gene (inherited from the mother and the father) have the mutation. Carriers of the gene have one copy of the mutation, but usually show no features of the condition.
How is the diagnosis of prolidase deficiency made?
Diagnosis of prolidase deficiency is usually made during infancy through identification of its typical clinical features and confirmatory investigations. Not all the clinical features are required to make the diagnosis. Investigations may confirm the presence of specific proteins (proline-containing dipeptides) in the urine (which may be called imidodipeptiduria), and low levels of prolidase enzyme in the blood.
Genetic testing may be useful in families known to carry the genetic mutation.
Treatment of prolidase deficiency
Treatment of prolidase deficiency is aimed at controlling symptoms, particularly the skin ulceration and infections. The response to treatments is variable between patients.