BACKGROUNDPartial tandem duplication of mixed lineage leukaemia (MLL-PTD) is detected both in patients with acute leukemia and in healthy people. However, MLL-PTD in relatives of patients with MLL-PTD has not been reported. The objective of this study was to investigate the expression of MLL-PTD in patients with acute leukemia and in their relatives.

METHODSThe bone marrow or peripheral blood was collected from patients with acute leukaemia and their relatives. Nested reverse transcription-polymerase chain reaction (RT-PCR) was applied to detect the mRNA expression of the MLLPTD fused gene, and further confirm in genomic DNA level.

RESULTSAnalysing MLL-PTD in case 1, the patient's older brother and his younger brother were positive, while his mother and his son were negative. The exon type in case 1 was e9/3 fusion, but in his older brother, it was e9/3 and e11/3 fusion, and in his younger brother, it was e9/3, e10/3, and e11/3 fusion. MLL-PTD in case 2 was negative, but in the patient's older sister was positive, and the exon type was e9/3, e10/3, and e11/3.

CONCLUSIONSThe expression of MLL-PTD was present in cases with acute leukaemia with a single expression type. However, various expression types were detected in their healthy relatives. MLL-PTD can couple with other chromosome aberrations, and its impact on disease prognosis remains to be studied further.