NEW YORK (Reuters Health) - In patients with Marfan syndrome, there is an association between homocysteine levels and the severity of cardiovascular manifestations, according to a new study. Homocysteine may therefore modulate the phenotypic expression of Marfan syndrome.
In the November issue of the European Heart Journal, Dr. Betti Giusti of the University of Florence in Florence, Italy reports with colleagues there and elsewhere on a study of 107 patients with Marfan syndrome and 189 control subjects. The Marfan syndrome patients were divided into three groups: no cardiac involvement, mild involvement, or aortic dilatation or dissection.
The authors explain that they were trying to identify not only an association between homocysteine levels and the cardiac manifestations of Marfan syndrome, but also a possible role for a mutation in the gene that encodes for methylenetetrahydrofolate reductase (MTHFR), an enzyme involved in methionine metabolism.
Hyperhomocysteinemia, defined as a homocysteine level above the 95th percentile in the control subjects, was documented in 34 of the Marfan syndrome patients. According to the investigators, total homocysteine in the group with aortic dilatation or dissection was significantly higher than in the group with only mild cardiac involvement. Furthermore, the homocysteine level was higher in patients with dissection than in those with dilatation.
The investigators note that the hyperhomocysteinemia in their patients was not related to reduced folate or vitamin B12 levels.
The authors also found the prevalence of homozygotes with the C677T MTHFR polymorphism to be “higher, but not significantly,” among patients with aortic dilatation or dissection compared to those with milder cardiac involvement. Homozygotes were, however, significantly more prevalent in the subgroup of patients with aortic dissection compared to the subgroup with aortic dilatation or compared to the group with mild manifestations.
“Our data indicate an association between the severity of the cardiovascular manifestations...and elevated total homocysteine levels,” the researchers conclude. “This suggests an important role for total homocysteine levels in determining phenotypic variability in Marfan patients and provides further evidence for the association of homocysteinemia with the damage of the vascular system.”
Source: Eur Heart J 2003;24:2038-2045. [ Google search on this article ]
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