Familial hyperhomocysteinemia, age and peripheral vascular diseases - an Italian study

Hyperhomocysteinemia is a widely recognized, although not yet entirely understood, risk factor for cardiovascular disease. Particularly, the complex relationships between age, hyperhomocysteinemia, predisposing genetic factors and peripheral vascular diseases have not been fully evaluated. Our contribution to this issue is a retrospective analysis of a large series of patients with peripheral arterial, venous and lymphatic disease, and of their blood relatives, with special reference to homocysteine plasma levels, age and methylenetetrahydrofolate reductase (MTHFR) polymorphisms. Serum homocysteine was measured in 477 patients (286 males, 191 females, age range 19-78 years) with various vascular clinical conditions: postphlebitic syndrome (46) recurrent venous ulcers (78), arterial diseases (101) primary lymphoedema (87), secondary lymphoedema (161) and outlet thoracic syndrome (4), and in 50 normal controls. A MTHFR study for polymorphisms was carried on in the subjects with homocysteine values exceeding 15 mol/L. Serum homocysteine determination and MTHFR polymorphism studies were performed also in 1430 healthy blood related relatives (mainly siblings, descendents and sibling descendents) of the subjects with hyperhomocysteinemia and MTHFR polymorphisms. We found MTHFR polymorphisms in 20% of controls and in 69.3%, 69.5% and 53.8% of hyperhomocysteinemic subjects with arterial diseases, postphlebitic syndrome and venous ulcers, respectively. As expected, the percentage of hyperhomocysteinemia in patients with secondary lymphoedema and with thoracic outlet syndrome did not show significant differences compared to the control group. A MTHFR polymorphism was found in 116 out of the 214 hyperhomocysteinemic patients, i.e., in the 54% of the overall patient population with hyperhomocysteinemia (214 patients). Interestingly 750 (52%) out of the 1430 blood relatives of the 116 patients with hyperhomocysteinemia and MTHFR polymorphisms showed at least one polymorphism in MTHFR gene. In this latter group of 750 healthy blood-related relatives bearing a MTHFR polymorphism the finding of hyperhomocysteinemia increased according to the age class from 1.6% in the age range <40 years up to 54.9% in the age range >60 years. The present study demonstrate that patients with peripheral arterial disease, post-phlebitic syndrome, venous ulcers and primary lymphoedema show a significantly higher incidence of hyperhomocysteinemia compared to controls, and adds further evidence to the causative role of hyperhomocysteinemia in the development of both arterial and venous disease. Moreover our data indicate a possible causative role of hyperhomocysteinemia in primary lymphoedema. In more than 50% of our hyperhomocysteinemic patients a polymorphism of MTHFR (C677T and/or A1298C) was detected. In subjects with these polymorphisms the frequency of hyperhomocysteinemia increases with age. We observed a quite similar frequency of the two polymorphisms in the studied population and therefore claim for the need to study both C677T and A1298C mutations in hyperhomocysteinemic patients.