12th Congress of the European Hematology ... - Haematologica

12 th Congress of the European Hematology Association
ly recognized polymorphism in Factor V (FV) gene (His1299Arg; also
named HR2) has been reported to be a possible risk factor for the development
of VTE. The significance of HR2 has not yet been tested in VTE
patients in Lebanon. Aims. The aim of this study is to evaluate the role
of HR2 polymorphism in VTE in a group of Lebanese patients. Methods.
Seventy-three VTE patients (40 males and 33 females) and 125 healthy
subjects (72 males and 53 females), were examined for HR2. The patients
were admitted to our medical center between March 2003 and December
2005. The average ages for the patients and controls were 45.0±19.1
years and 35.4±18.6 years, respectively. The DNA was extracted and
stored at -80°C for later use and the CVD StripAssay (ViennaLab, Austria)
was used. The thermocycler program consists of an initial step of
94°C for 2 minutes, followed by 35 cycles of 94°C for 15 seconds, 58°C
for 30 seconds, 72°C for 30 seconds, and a final extension step of 72°C
for 3 minutes. The amplification products are selectively hybridized to
a test strip which contains allele-specific (Wild type and Mutant)
oligonucleotide probes immobilized as an array of parallel lines. Bound
biotinylated sequences are detected using streptavidin-alkaline phosphatase
and color substrates. Results. Thirty-six patients (82.2%) had
DVT, 8 patients (11%) had PE, and 5 patients (6.8%) had both. There
was significant association between FV Leiden and VTE (p15 U/mL) we found high titters of
antibodies in 41 subjects: 24 patients (7.8%) and 17 controls (6.1%)
(non-significant difference). Considering the requirement for internal
cut-off points we tested the 90th, 95th, 97.5th and 99th percentiles of
our normal population obtaining a non-significant association in every
case. Likewise occurs following the gender stratification or the exclusion
of 73 carriers (56 patients and 17 controls) of thrombophilic mutations.
The prevalence was similar among the recurrent cases. Anti-B2GPI (IgM
isotype). We only found 20 positive samples (3.4%) using the manufacturer
criteria (>15 U/mL) with similar prevalence in patients and controls.
Considering the same internal cut-off points, we observed a borderline
excess of women (p=0.03) among the patients, using the 95th percentile
(10 U/mL) that declines at P97.5th and disappears at P99th. Conclusions.
Our study did not allow associate the VTE and high levels of the IgG or
IgM anti-B2GPI antibodies even by means of in-house ranges of positivity.
The recommended utilization of a different cut-off (calculated for
each laboratory with the 99th percentile) did not increase the potential
utility of this assay. Why these upper ranges of antibodies could work
apparently better when they are considered as diagnostic criteria for the
APS (among lupus patients) than as independent related factors in a random
population with thrombosis is unclear (although might be an issue
of pre-test probability).
This work was supported by the grants FIS #030839 and #041550