The involvement of MLL in 11q23 and ARHGEF17 in 11q13 was ascertained in only 1 case (Teuffel et al., 2005). It was an unusual case of treatment-related MLL rearrangement in the absence of leukemia.

The case reported by Teuffel et al. (2005), was a five-year-old girl, who experienced an acute myeloid leukemia (AML) with a variant t(8;21) and achieved remission under treatment. Four years later, a follow-up control of her karyotype revealed a t(11;11)(q13;q23), in the absence of any sign of leukemia in the bone marrow, over a period of 30 months following the discover of the t(11;11).
Other cases of t(11;11)(q13;q23) were:
A 13-year-old girl, who have had a M4eo AML with inv(16)(p13q22). Eleven month later, a t(11;11)(q13;q23) was found, but bone marrow remained normal; however, an overt M5b AML was diagnosed 6 months later (Leblanc et al., 1994). This case resembles the case of Teuffel.
There was also the case of a 69-year-old male patient with a primary M4 AML, who died 5 months after diagnosis, and an AML (not classified) female patient (Testa et al., 1985; Mackinnon and Campbell, 2007).

In the case reported by Teuffel, the MLL-ARHGEF17 was only seen in the myeloid lineage. The myeloid differentiation was not perturbed by the presence of the chimeric protein, and normal mature myeloid cells carrying the chimeric protein were found in normal amounts.

The fusion between MLL and ARHGEF17 occurred in introns 12 and 1 respectively.