A 2-es típusú Janus tirozin kináz Val617Phe aktiváló pontmutáció szerepe és kimutatásának jelentősége myeloproliferatív szindrómában = Role of the activating mutation Val617Phe of Janus kinase 2 gene in myeloproliferative diseases and significance of its detection

A myeloproliferativ szindroma a hematopoietikus őssejt klonalis zavara, amelynek kialakulasaban feltehetően reszt vesz a 2-es tipusu Janus kinaz gen Val617Phe pontmutacioja. Az aktivalo mutacio előfordulasi gyakorisaga az eddigi adatok szerint polycytaemia veraban 80%, essentialis thrombocythaemiaban 35%, kronikus idiopathias myelofibrosisban pedig 50% koruli ertekeket mutat. A fent emlitett korkepek diagnozisa eddig szekunder faktorok kizarasan, valamint csontvelő biopszias vizsgalaton alapult. Munkank celja egyszerű es rutin korulmenyek kozott alkalmazhato molekularis genetikai technikak beallitasa volt a 2-es tipusu Janus kinaz gen Val617Phe pontmutacio kimutatasara. Az adatok segitsegevel a mutacio pozitiv es mutacio negativ myeloproliferativ szindromaban szenvedő betegek klinikai adatait kivantuk osszehasonlitani. A Val617Phe mutacio előfordulasi gyakorisagat 252 myeloproliferativ szindroma miatt gondozott beteg periferias vermintajabol vizsgaltuk allel specifikus polimeraz lancreakcioval. Polycytaemia veraban a mutacio előfordulasi gyakorisaga 85,4% (117/137), essentialis thrombocytaemiaban 56,6% (56/99), kronikus idiopathias myelofibrosisban pedig 87,5% (14/16) volt. A Val617Phe-pozitiv polycytaemia veraban es essentialis thrombocythaemiaban szenvedő betegcsoportokban szignifikansan nagyobb, a diagnozis megallapitasakor mert hemoglobinszint es feherversejtszam ertekeket talaltunk, mint a Val617Phe-negativ betegeknel. A splenomegalia es a kulonboző szovődmenyek (trombozis, verzes, transzformacio akut leukemiaba) előfordulasi gyakorisaga nem tert el szignifikansan a Val617Phe-pozitiv, illetve negativ csoportok kozott. Osszefoglalaskent megallapithato, hogy a 2-es tipusu Janus kinaz Val617Phe mutacio-analizis rutin laboratoriumban kivitelezhető, nem invaziv modszer, amely nagymertekben segiti a myeloproliferativ szindroma differencialdiagnosztikajat. Bar a Val617Phe mutacio-kimutatas pontos helye a myeloproliferativ szindroma diagnosztikai algoritmusaban jelenleg meg nem kerult meghatarozasra szeleskorű szakmai konszenzus alapjan, a vizsgalat elvegzese javasolt ismeretlen eredetű erythrocytosis es thrombocytosis eseten. The Val617Phe point mutation of Janus kinase 2 gene is believed to participate in the pathogenesis of myeloproliferative syndrome characterised by the clonal alteration of hematopoetic stem cells. According to current results, the frequency of Val617Phe activating mutation is around 80% in polycythaemia vera, 35% in essential thrombocythaemia, and 50% in chronic idiopathic myelofibrosis. The diagnoses of polycythaemia vera, essential thrombocythaemia and idiopathic myelofibrosis were so far based on the exclusion of secondary factors as well as bone marrow biopsy histology. The goal of the present work was to establish simple molecular genetic techniques for the routine testing of Janus kinase 2 gene Val617Phe mutation, and to compare the clinical phenotypes of Val617Phe mutation positive and negative myeloproliferative syndromes. We employed the allele specific polymerase chain technique for detection of Val617Phe mutation in 252 patients with myeloproliferative syndrome. We measured Val617Phe frequency as 85,4% (117/137) in polycytaemia vera, 56,6% (56/99) in essential thrombocythaemia, and 87,5% (14/16) in idiopathic myelofibrosis. We found significantly elevated hemoglobin levels and white blood cell counts (measured at the time of diagnosis) in Val617Phe-positive polycythaemia vera and essential thrombocythaemia patient groups compared to Val617Phe-negative patients. However, the frequencies of splenomegaly and other complications (thrombosis, bleeding, transformation to acute leukemia) were not significantly different between the mutation-positive and negative groups. In conclusion, the non-invasive mutation analysis of the Janus kinase 2 Val617Phe is suitable for routine laboratory application and helps the differential diagnosis of myeloproliferative syndrome. Althought the exact role of Val617Phe mutation testing has not yet been identified on the basis of a broad professional consensus, the testing is suggested in cases of erythrocytoses and thrombocytoses of unknown origin.