PROLIDASE DEFICIENCY - BIOCHEMICAL-STUDY OF ERYTHROCYTE AND SKIN FIBROBLAST PROLIDASE ACTIVITY IN ITALIAN PATIENTS

Background and methods. Prolidase deficiency (PD), a rare, autosomally inherited disorder causing iminodipeptiduria is associated with a num ber of clinical manifestations, the principle feature being chronic sk in ulceration. The enzyme prolidase cleaves iminodipeptides containing C-terminal prolyl or hydroxyprolyl residues and is important in the f inal stages of protein catabolism. We report clinical and biochemical findings in 8 Italian patients with proven prolidase deficiency. There was considerable heterogeneity in age at onset of symptoms (varying f rom 3-17 years), mental retardation and clinical manifestations (asymp tomless to very severe). Prolidase activity was determined in hemolysa tes of patient erythrocytes and cultured dermal fibroblasts. Results. Prolidase activity was found to be deficient, especially against gly-p ro. Erythrocyte and fibroblast enzyme was also separated into two form s, a major isoform (I) and a minor one (II) by fast protein liquid chr omatography, and activity against different iminodipeptide substrates was tested. Isoform I activity was markedly reduced in all patients as compared to normal controls, while isoform II activity appeared to be unaltered. Conclusions. We were unable to find any correlation betwee n degree of enzyme activity loss and severity of symptoms.