THROMBOMODULIN AND RISTOCETINCOFACTOR IN HOMOCYSTINURIA - A STUDY IN 2 SIBLINGS

Homocystinuria due to cystathionine-beta-synthase deficiency (CBS-def- HOCY) initially often presents with vascular disorders, e.g. thromboem bolic events. The measurement of vascular endothelial markers in plasm a could help to assess endothelial damage. We determined von Willebran d factor (measured as Ristocetincofactor, RiCoF) and thrombomodulin (T M), two endothelial cell markers to our knowledge not measured systema tically before in homocystinuria patients in a longitudinal study of t wo homocystinuric patients: Patient 1 with thromboembolic disease and his asymptomatic sister, patient 2. Before start of therapy in patient 1, TM and RiCoF levels both were increased. In patient 2 a moderately elevated RiCoF and a normal level of TM were found. Vitamin therapy w ith 15 mg folate and 600 mg pyridoxine per day led to almost complete normalization of amino acids in urine and plasma, and complete normali zation of RiCoF and TM levels in both patients. Thus, TM and RiCoF ele vations demonstrate that CBS-def-HOCY leads to endothelial cell damage , which resolved under vitamin therapy in the patients studied.