No abstract

An enzyme‐linked immunofiltration assay (ELIFA) was developed for detecting anti‐human platelet factor 4 (hPF4)–heparin antibody in sera of patients with heparin‐induced thrombocytopenia (HIT). The immunofiltration assay was developed to capture HIT antibody by hPF4–heparin complex adsorbed onto a positively charged nylon membrane, as an alternative to plastic bound hPF4. Of 75 sera with a positive serotonin‐release assay (SRA), anti‐PF4–heparin of the immunoglobulin (Ig)G class was detected in 72 (96%) sera. With SRA‐negative sera from thrombocytopenic patients treated with heparin, anti‐hPF4–heparin IgG and IgA were detected in 16% (n = 126) and 14% (n = 74) of sera respectively; 6% (n = 71) of SRA‐negative sera contained both IgG and IgA anti‐hPF4–heparin antibodies. The detection of anti‐hPF4–heparin IgG in all HIT sera supports the assay of anti‐PF4–heparin IgG as being a sensitive screening test for HIT. Alternatively, the absence of anti‐hPF4–heparin IgA cannot be used as a test for excluding HIT, as it was detected in only 48% of SRA‐positive HIT sera. However, it may be used to support the diagnosis of HIT, when HIT IgG is weak. This study emphasized the need to use different immobilizing media for the capture of anti‐PF4–heparin antibody.

The 20210G→A mutation in the 3′‐untranslated (UT) region of the prothrombin gene is extremely rare or absent in the Chinese population (0 in 449 subjects, 140 with a history of thromboembolism). This is in contrast to the results from 302 Caucasians from Australia in our study (4·6% in 153 patients with a thromboembolic history and 1·3% in 149 patients with no history). This rarity implies that the variant of the prothrombin gene is probably not the main cause of venous thromboembolism in the Chinese population. Even among Caucasians this mutation accounts for only a minor percentage of all patients with thromboembolism. The relatively low incidence of venous thromboembolism in the Chinese population compared with Caucasians is probably as a result of the low prevalence of factor V Leiden or other environmental or genetic factors.

The 20210G-->A mutation in the 3'-untranslated (UT) region of the prothrombin gene is extremely rare or absent in the Chinese population (0 in 449 subjects, 140 with a history of thromboembolism). This is in contrast to the results from 302 Caucasians from Australia in our study (4.6% in 153 patients with a thromboembolic history and 1.3% in 149 patients with no history). This rarity implies that the variant of the prothrombin gene is probably not the main cause of venous thromboembolism in the Chinese population. Even among Caucasians this mutation accounts for only a minor percentage of all patients with thromboembolism. The relatively low incidence of venous thromboembolism in the Chinese population compared with Caucasians is probably as a result of the low prevalence of factor V Leiden or other environmental or genetic factors.