Wafa Abdulsamad, As'sad Manar, Liehr Thomas, Aljapawe Abdulmunim, Al Achkar Walid
Molecular Biology and Biotechnology Department, Human Genetics Div., Atomic Energy Commission of Syria, P.O. Box 6091, Damascus, Syria.
Jena University Hospital, Institute of Human Genetics, Kollegiengasse 10, D-07743, Jena, Germany.
J Med Case Rep. 2017 Apr 7;11(1):94. doi: 10.1186/s13256-017-1251-1.
The translocation t(1;19)(q23;p13), which results in the TCF3-PBX1 chimeric gene, is one of the most frequent rearrangements observed in B cell acute lymphoblastic leukemia. It appears in both adult and pediatric patients with B cell acute lymphoblastic leukemia at an overall frequency of 3 to 5%. Most cases of pre-B cell acute lymphoblastic leukemia carrying the translocation t(1;19) have a typical immunophenotype with homogeneous expression of CD19, CD10, CD9, complete absence of CD34, and at least diminished CD20. Moreover, the translocation t(1;19) correlates with known clinical high risk factors, such as elevated white blood cell count, high serum lactate dehydrogenase levels, and central nervous system involvement; early reports indicated that patients with translocation t(1;19) had a poor outcome under standard treatment.
We report the case of a 15-year-old Syrian boy with pre-B cell acute lymphoblastic leukemia with abnormal karyotype with a der(19)t(1;19)(q21.1;p13.3) and two yet unreported chromosomal aberrations: an interstitial deletion 6q12 to 6q26 and a der(13)t(1;13)(q21.1;p13). According to the literature, cases who are translocation t(1;19)-positive have a significantly higher incidence of central nervous system relapse than patients with acute lymphoblastic leukemia without the translocation. Of interest, central nervous system involvement was also seen in our patient.
To the best of our knowledge, this is the first case of childhood pre-B cell acute lymphoblastic leukemia with an unbalanced translocation t(1;19) with two additional chromosomal aberrations, del(6)(q12q26) and t(1;13)(q21.3;p13), which seem to be recurrent and could influence clinical outcome. Also the present case confirms the impact of the translocation t(1;19) on central nervous system relapse, which should be studied for underlying mechanisms in future.
导致TCF3 - PBX1嵌合基因的t(1;19)(q23;p13)易位是B细胞急性淋巴细胞白血病中最常见的重排之一。它在成人和儿童B细胞急性淋巴细胞白血病患者中均有出现，总体频率为3%至5%。大多数携带t(1;19)易位的前B细胞急性淋巴细胞白血病病例具有典型的免疫表型，CD19、CD10、CD9呈均匀表达，CD34完全缺失，且CD20至少减少。此外，t(1;19)易位与已知的临床高危因素相关，如白细胞计数升高、血清乳酸脱氢酶水平升高和中枢神经系统受累；早期报告表明，携带t(1;19)易位的患者在标准治疗下预后较差。
我们报告了一名15岁叙利亚男孩，患有前B细胞急性淋巴细胞白血病，核型异常，存在der(19)t(1;19)(q21.1;p13.3)以及另外两个尚未报道的染色体畸变：6号染色体q12至q26的间质缺失和der(13)t(1;13)(q21.1;p13)。根据文献，t(1;19)易位阳性的病例中枢神经系统复发的发生率明显高于无该易位的急性淋巴细胞白血病患者。有趣的是，我们的患者也出现了中枢神经系统受累。
据我们所知，这是首例儿童前B细胞急性淋巴细胞白血病病例，存在不平衡的t(1;19)易位以及另外两个染色体畸变，即del(6)(q12q26)和t(1;13)(q21.3;p13)，这些畸变似乎具有复发性，可能影响临床结局。此外，本病例证实了t(1;19)易位对中枢神经系统复发的影响，未来应对其潜在机制进行研究。
