Diagnostic Strategy for Detection of Typical and Atypical BCR-ABL Fusion Gene Transcripts in Chronic Myeloid Leukemia

Background & Aims. The diagnosis of chronic myeloid leukemia (CML) is confirmed when t(9;22)(q34;q11) translocation is found by the cytogenetic test method and/or chimeric BCR-ABL transcript is detected by the reverse transcription polymerase chain reaction (RT-PCR). It is known that two most common types of chimeric BCR-ABL transcript are determined in CML patients: e13a2 (b2a2) и e14a2 (b3a2). However, rare types of chimeric BCR-ABL transcript have been described and they may be overlooked. Moreover, timely diagnosing and detection of different types of the chimeric transcript are very important, because the clinical course of the disease and efficacy of the therapy with tyrosine kinases inhibitors depend on the structure of chimeric BCR-ABL gene. Since in some cases CML may be diagnosed without the standard cytogenetic test and be confirmed by RT-PCR alone, we consider it important to develop a diagnostic algorithm which might permit to determine almost any type of chimeric BCR-ABL transcript.

Methods. Over the period from January, 2004, till December, 2013, in the laboratory of molecular biology of the department of pediatric oncology and hematology in Regional Children’s Hospital No. 1 (Yekaterinburg), the diagnosis of CML was confirmed in 1082 patients: 531 (49 %) males and 551 (51 %) females. The median age was 50 years (range 5–88 years). All patients underwent standard cytogenetic and molecular genetic tests. Primers which are complementary to nucleotide ABL gene sequence are localized in 2 and 3 ABL exons and are used for detection of all transcript types. Primers which are complementary to nucleotide BCR gene sequence are localized either in 12 and 13 exons for detection of most typical e13a2 and e14a2 (M-bcr) transcripts or in exon 1 for detection of e12a (m-bcr) transcript. While detecting amplicons which size differs from that of e13a2, e14a2, and e1a2, their direct paired-end sequencing is performed using primers (applied during the second round of RT-PCR) and a Big Dye Terminator 3.1 kit.

Results. After having analyzed 1082 patients with confirmed CML, we have developed a diagnostic algorithm for detecting common and rare types of chimeric BCR-ABL transcript in CML using RT-PCR. We detected common chimeric BCR-ABL transcripts, e14a2 and e13a2, in 62.53 % and 35.89 % of cases, respectively, using this algorithm. Rare transcripts, e13a3, e14a3, e19a2, e1a2, e3a2, e6a2, and e8a2, were detected in 1.57 % of cases.

Conclusion. Therefore, the proposed diagnostic algorithm proved to be effective for detection of common and rare types of chimeric BCR-ABL transcripts in CML patients.

• O.V. Nikulina Regional Children’s Hospital No. 1, 32 Serafimy Deryabinoy str., Yekaterinburg, Russian Federation, 620149; Research Institute of Medical Cell Technologies, 22a K. Marksa str., Yekaterinburg, Russian Federation, 620026 ; ГБУЗ СО «Областная детская клиническая больница № 1», ул. Серафимы Дерябиной, д. 32, Екатеринбург, Российская Федерация, 620149; ГАУЗ СО «Институт медицинских клеточных технологий», ул. К. Маркса, д. 22а, Екатеринбург, Российская Федерация, 620026
• Grigorii Anatol’evich Tsaur Regional Children’s Hospital No. 1, 32 Serafimy Deryabinoy str., Yekaterinburg, Russian Federation, 620149; Research Institute of Medical Cell Technologies, 22a K. Marksa str., Yekaterinburg, Russian Federation, 620026; Ural State Medical University, 3 Repina str., Yekaterinburg, Russian Federation, 620219 ; ГБУЗ СО «Областная детская клиническая больница № 1», ул. Серафимы Дерябиной, д. 32, Екатеринбург, Российская Федерация, 620149; ГАУЗ СО «Институт медицинских клеточных технологий», ул. К. Маркса, д. 22а, Екатеринбург, Российская Федерация, 620026; ГБОУ ВПО «Уральский государственный медицинский университет» Минздрава России, ул. Репина, д. 3, Екатеринбург, Российская Федерация, 620219
• T.O. Riger Regional Children’s Hospital No. 1, 32 Serafimy Deryabinoy str., Yekaterinburg, Russian Federation, 620149; Research Institute of Medical Cell Technologies, 22a K. Marksa str., Yekaterinburg, Russian Federation, 620026 ; ГБУЗ СО «Областная детская клиническая больница № 1», ул. Серафимы Дерябиной, д. 32, Екатеринбург, Российская Федерация, 620149; ГАУЗ СО «Институт медицинских клеточных технологий», ул. К. Маркса, д. 22а, Екатеринбург, Российская Федерация, 620026
• Yu.A. Yakovleva Regional Children’s Hospital No. 1, 32 Serafimy Deryabinoy str., Yekaterinburg, Russian Federation, 620149; Research Institute of Medical Cell Technologies, 22a K. Marksa str., Yekaterinburg, Russian Federation, 620026 ; ГБУЗ СО «Областная детская клиническая больница № 1», ул. Серафимы Дерябиной, д. 32, Екатеринбург, Российская Федерация, 620149 2 ГАУЗ СО «Институт медицинских клеточных технологий», ул. К. Маркса, д. 22а, Екатеринбург, Российская Федерация, 620026
• A.S. Demina Regional Children’s Hospital No. 1, 32 Serafimy Deryabinoy str., Yekaterinburg, Russian Federation, 620149; Research Institute of Medical Cell Technologies, 22a K. Marksa str., Yekaterinburg, Russian Federation, 620026 ; ГБУЗ СО «Областная детская клиническая больница № 1», ул. Серафимы Дерябиной, д. 32, Екатеринбург, Российская Федерация, 620149; ГАУЗ СО «Институт медицинских клеточных технологий», ул. К. Маркса, д. 22а, Екатеринбург, Российская Федерация, 620026
• E.R. Semenikhina Regional Children’s Hospital No. 1, 32 Serafimy Deryabinoy str., Yekaterinburg, Russian Federation, 620149 ; ГБУЗ СО «Областная детская клиническая больница № 1», ул. Серафимы Дерябиной, д. 32, Екатеринбург, Российская Федерация, 620149
• T.V. Spil’nik Ural State Medical University, 3 Repina str., Yekaterinburg, Russian Federation, 620219 ; ГБОУ ВПО «Уральский государственный медицинский университет» Минздрава России, ул. Репина, д. 3, Екатеринбург, Российская Федерация, 620219
• LI Savel’ev Regional Children’s Hospital No. 1, 32 Serafimy Deryabinoy str., Yekaterinburg, Russian Federation, 620149; Research Institute of Medical Cell Technologies, 22a K. Marksa str., Yekaterinburg, Russian Federation, 620026; Ural State Medical University, 3 Repina str., Yekaterinburg, Russian Federation, 620219 ; ГБУЗ СО «Областная детская клиническая больница № 1», ул. Серафимы Дерябиной, д. 32, Екатеринбург, Российская Федерация, 620149; ГАУЗ СО «Институт медицинских клеточных технологий», ул. К. Маркса, д. 22а, Екатеринбург, Российская Федерация, 620026; ГБОУ ВПО «Уральский государственный медицинский университет» Минздрава России, ул. Репина, д. 3, Екатеринбург, Российская Федерация, 620219
• L.G. Fechina Regional Children’s Hospital No. 1, 32 Serafimy Deryabinoy str., Yekaterinburg, Russian Federation, 620149; Research Institute of Medical Cell Technologies, 22a K. Marksa str., Yekaterinburg, Russian Federation, 620026 ; ГБУЗ СО «Областная детская клиническая больница № 1», ул. Серафимы Дерябиной, д. 32, Екатеринбург, Российская Федерация, 620149; ГАУЗ СО «Институт медицинских клеточных технологий», ул. К. Маркса, д. 22а, Екатеринбург, Российская Федерация, 620026

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