AML hastalarında t(15;17) PML-RARA translokasyonunun real time RT-PCR ile 5 yıllık sonuçlarının değerlendirilmesi

Amaç: Akut promyelösitik lösemi (APL), akut myeloid löseminin (AML) iyi tanımlanmış alt tipidir ve spesifik olarak t(15;17)(q22;q12) translokasyonu ile karakterizedir. t(15;17), 15. kromozom üzerinde bulunan promyelösitik lösemi (PML) ve 17. kromozomda lokalize retinoik asit reseptör alfa (RARA) genlerinin füzyonu sonucu oluşur. Translokasyon varlığı, konvansiyonel sitogenetik, floresan in situ hibridizasyon analizi (FISH) ve sıklıkla gerçek zamanlı kantitatif revers transkriptaz polimeraz zincir reaksiyonu (qRT-PCR) yöntemiyle saptanır. Bu çalışmada, anabilim dalımıza başvuran APL ön tanılı olgulara ait kan ya da kemik iliği materyallerinden t(15;17) translokasyonunun gerçek zamanlı qRT-PCR ile kantitasyonu amaçlanmıştır. Gereç ve Yöntem: Çalışmaya 2009-2013 yılları arasında başvuran 79 çocuk (7.28±5.20 yaş; 45 E, 34 K) ve 359 yetişkin (47.71±15.57 yaş; 193 E, 166 K) olgu dahil edilmiştir. Olguların kan ya da kemik iliği materyallerinden total RNA izolasyonunu takiben cDNA sentezi gerçekleştirilmiştir. Sonrasında, qRT-PCR ile t(15;17) translokasyonu çalışılıp, kantite edilmiştir. Bulgular: Çocuk olgulardan 2'si (%3), toplamda 6 test (%5) t(15;17) için pozitif olarak belirlenmiştir. Bu olgulara ait t(15;17) kantitasyon değeri ortalaması, 0.0002±0.0003tür. Yetişkin olguların 26'sı (%7), toplamda 30 test (%8) t(15;17) için pozitif olarak belirlenmiştir. Bu olgulara ait t(15;17) kantitasyon değeri ortalaması, 0.067±0,144tür. Sonuç: qRT-PCRın konvensiyonel sitogenetik çalışmalara göre üstünlüğü, tüm çalışma basamaklarının test esnasında eş zamanlı olarak izlenebilmesi ve oluşan amplikonların kantitasyonunun yapılabilmesidir. t(15;17) kalitatif tayininin klinikteki önemi, tanının kesinleştirilmesinde, tüm trans-retinoik asit ve trioksid arsenik tedavisine yanıtın öngörülmesi ve tedavinin yararlılığının bilinmesinde, minimal rezidüel hastalığın (MRH) takibi ve relapsın erken evrede belirlenebilmesidir.

Identification of t(15;17) PML-RARA translocation in acute promyelocytic leukemia prediagnosed children and adult cases by real time qRT-PCR with 5 year follow up results

Aim: Acute promyelocytic leukemia (APL) is a well-defined subtype of acute myeloid leukemia (AML) specifically characterized by the t(15;17)(q22;q12) translocation. t(15;17) results in the fusion of the genes, promyelocytic leukemia (PML) on chromosome 15 and retinoic acid receptor alpha (RARA) located on 17th chromosome. Translocation is detected by conventional cytogenetic, fluorescence in situ hybridization analyses (FISH) and often a real time quantitative reverse transcriptase polymerase chain reaction (qRT-PCR) method. In this study, quantification of t(15; 17) translocation via real time qRT-PCR was aimed in blood or bone marrow materials belonging to APL pre-diagnosed cases that appealed our department. Materials and Methods: Seventy nine children (7.28 ± 5.20 years; 45 M, 34 F) and 359 adults (47.71 ± 15.57 years; 193 M, 166 F) were included in the study between the years 2009-2013. Following total RNA isolation from blood or bone marrow materials of the cases, cDNA synthesis was carried out. Then, t(15; 17) translocation was studied by qRT-PCR and quantitated. Results: Two cases from children (3%), and in total 6 tests (5%) were detected positive for t(15;17). The average t(15;17) quantification value was 0.0002 ± 0.0003. Twenty six cases of the adults (7%), in total 30 tests (8%) were determined as t(15;17) positive. Average t(15;17) quantification value of these cases was 0.067 ± 0.144. Conclusion: The superiority of qRT-PCR compared to conventional cytogenetic studies can be found in the fact that all working steps can be monitored simultaneously during the test and the resulting amplicons can be quantitated. The clinical significance of t(15;17) qualitative determination is, confirmation of the diagnosis, all trans-retinoic acid and trioxide arsenic treatment response prediction and treatment efficacy knowledge in addition to minimal residual disease (MRD) monitoring and ability to identify relapse at early ages.

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