Thrombophilic Mutations in Iran

years at least six weeks after foetal loss and normal delivery, respectively. The G1691A genotype in the factor V gene, the prothrombin G20210A variant, and the TT genotype in the gene of methylenetetrahydrofolate reductase (MTHFR) were assessed as previously described (3). Lp(a) concentration was measured with ELISA technique using anti-apo(a) capture antibodies and anti-apo B detection antibodies; the apolipoprotein(a) (apo(a)) size polymorphism was determined by SDS agarose gel electrophoresis and anti-apo(a) immunblotting (4). Compared with controls women with recurrent foetal loss in the first trimester of pregnancy were more frequently carriers of the factor V G1691A genotype (patients vs. controls, odds ratio (OR)/95% confidence interval (CI): 10% vs. 4.3%, 2.3/0.4-13.5), the MTHFR TT genotype (22.5% vs. 8.7%, 3/0.9-10.8) and the prothrombin G20210A variant (0% vs. 2.17%). These differences did not reach statistical significance. Most interestingly, however, women with recurrent foetal loss had significantly higher serum levels of Lp(a) (median: 360 mg/l, range 0-1700 mg/l) compared with healthy control women (median: 50 mg/l, range 0-820 mg/l; p <0.0001, Wilcoxon-test). Lipoprotein(a) levels above the cardiovascular threshold value of 300 mg/l (5) were found in 35% of patients but only 6.5% of controls (OR: 7.7, 95% CI: 2-29.4; p <0.001, Fisher’s exact test). Lp(a) contains a protease kringle V-like domain and a variable number of kringle IV repeats, all of which have strong structural homologies to plasminogen (6). In addition, the number of kringle IV repeats is genetically determined and leads to the synthesis of apo(a) isoforms, which are inversely correlated to Lp(a) plasma concentrations (6, 7). In agreement with the strong genetic determination of Lp(a) concentrations (8) we found an increased frequency of small apo(a) isoforms which determine high Lp(a) levels (p <0.001). The median numbers of kringle IV repeats were 27 (range: 20-35) in the patient group and 34 in the control group (range 21-35) respectively. Elevated Lp(a) is a well-established risk factor of coronary artery disease and stroke (5, 8). In addition, elevated Lp(a) has been associated with thromboembolic disease in childhood (4), preeclampsia (2), and foetal growth retardation (9). Both in vitro and in vivo Lp(a) was found to exert negative effects on fibrinolysis and endothelial function (8, 10) which may impair the uteroplacental perfusion and thereby interfere with normal foetal growth and development. In conclusion, our data suggest that elevated Lp(a) is a genetic risk factor of recurrent foetal loss in the first trimester of pregnancy. However, this finding should be confirmed in a large prospective multicenter study with suitable methods to determine Lp(a). Since EIA methods targeting only the apo(a) moiety can overestimate the Lp(a) concentration with predominantly larger apo(a) isoforms and underestimate the plasma concentration of individuals with small apo(a) isoforms, we suggest to use either an EIA technology including anti-apo(a) capture antibodies and anti-apo B antibodies for detection or the determination of apo(a) by SDS agarose gel electrophoresis respectively (11).