Prolidase deficiency. Imidodipeptidase deficiency.
Incidence
It is an autosomal recessive disorder. More than 20 cases were reported by 1984.
Clinical Characteristics
This condition is characterized by skin lesions, frequent infections and mental retardation. The skin lesions are telangiectasia on the face, palms, and soles and purpuric, echymotic, crusting erythematous lesions which may proceed to ulceration, particularly on the lower extremities. The leg ulceration may be present in infancy but mainly from childhood to adulthood. There is always mild mental retardation from childhood on through adolescence and adulthood. Frequent infections may be present from the neonatal period and can occur at any age. There seems to be a unique face on this patients. Patients may have hepatosplenomegaly. Recently there has been found an association of prolidase deficiency with systemic lupus erythematosus (SLE). Both conditions are associated with disturbances in immune function and have clinical symtoms in common. Prolidase deficiency may be a risk factor for SLE, so patients with SLE with positive family history of SLE or presentation in childhood should be investigated for prolidase deficiency. Affected patients excrete massive amounts of imidodipeptides in the urine. The urinary iminodipeptides are elevated at all ages. After gelatin ingestion, the excretion of iminoacids in the urine is increased. Prolidase catalyses the hydrolysis of di and tripeptides with carboxy-terminal proline and plays an important role in the recycling of proline. Prolidase activity in RBC or white cells and fibroblasts are decreased in all ages. This disorder is associated with significant morbidity and even mortality. There is no satisfactory therapy for the disorder. Transfusion of concentrated RBC may help in the healing of leg ulcers, but they recurred after 1 1/2 year of last transfusion. In cases associated with SLE, oral prednisolone seems to improve the clinical condition.
Precipitants
no
Provocation Tests
After gelatin ingestion, the excretion of iminoacids in the urine is increased.
Diagnostic Procedures
EB-R, EB-W, EB-F. Prolidase activity in RBC or white cells and fibroblasts are decreased in all ages. Affected patients excrete massive amounts of imidodipeptides in the urine at all ages.