Thrombosis in MPN patients and gene frequency of human platelet antigens HORVAT I.1, Radić Antolic M.1, Rončević P., 2Serventi-Seiwerth R.2, Zadro R.1 1 Department of Laboratory Diagnostics, 2 Hematology Division - Department of Medicine University Hospital Center Zagreb School of Medicine INTRODUCTION AIM Thrombosis is the most common complication in MPN patients. Besides hereditary thrombophilia factors, polymorphisms in human platelet antigens (HPA) may be associated with increased risk for thrombosis. The aim of this study was to investigate HPA genotype frequencies and association of genotype with risk for thrombosis in a group of 99 JAK2 V617F positive MPN patients including additional risk factors. 1 METHODS ASO PCR was performed for JAK2 V617F according to Baxter et al, Lancet 2005. Genotype analysis was done for hereditary thrombosis risk factors (FV Leiden and FII G20210A using PCR-RFLP, Zöller et al, J Clin Invest 1994) and for HPA -1, -2, -3, -5 polymorphisms (Real-time PCR, Ficko et al, Transfus Med 2004). RESULTS Table 1. and 2. General information about 99 JAK2 V617F postive patients Female, N=59 Diagnosis Male, N=40 Diagnosis Age at diagnosis FV Leiden heterozygotes FII 20210A heterozygotes Additional risk factors hypertension diabetes smoking alcohol consumption lipemia PV=19 ET=32 MF=8 MDS/MPN=1 PV=18 ET=9 MF=11 MDS/MPN=2 median =58y (14-85 years) 3/99 3/99 99 patients 50/99 had at least one of additional risk factors with thrombosis N= 26 without thrombosis N= 73 Table 3. and 4. HPA genotype frequency HPA1 HPA2 HPA3 HPA5 HPA1 HPA2 HPA3 aa ab bb aa ab bb aa ab bb 0,01 0,79 0,20 0,23 0,77 0,14 0,51 0,34 0,69 0,31 0,35 0,42 0,24 HPA5 aa ab bb aa ab bb 0,77 0,22 0,96 0,04 CONCLUSIONS HPA 5 genotype frequency was statistical different between patients with and without thrombosis (P=0,036) showing that b allele could have protective role in these patients There was no statistical difference in gender, age, diagnosis, hereditary and additional risk factors between patients with and without thrombosis.