Infant acute lymphoblastic leukemia (ALL)

Poorly defined, only one case described to date, a 9-months-old boy with Pro-B ALL (FAB L1) (Alonso et al., 2010).

Patient achieved complete remission on day 33 of treatment and 5 months since diagnosis presented a bone marrow relapse. The patient had no available compatible donor and he did not receive a second line treatment and palliative care was administered. He died due to progressive disease.

Infant-ALL with 11q23 abnormality/MLL gene rearrangement has been defined as a type of leukemia with poor prognosis (Pieters et al., 2007). The patient relapsed at +5 months and died due to progressive disease.

Fusion gene MLL-BTBD18 (Alonso et al., 2010) was detected by LDI-PCR, as described (Meyer et al., 2005).

46,XY,inv(11)(q13q23) as sole abnormality.

Split-FISH analysis revealed two signals corresponding to the 3 and the 5 probes, both on the long arm of chromosome 11 (Alonso et al., 2010).

MLL Dual Color Break Apart Rearrangement Probe.

In frame fusion between the truncated MLL exon 10 and the truncated BTBD18 exon 3.

MLL-BTBD18.

RT-PCR (van Dongen et al., 1999; Alonso et al., 2010).

Fusion protein of 1989 amino acids containing 1374 codons from the amino-terminal region of MLL and 614 codons from the carboxy terminal portion of the BTBD18 protein, plus "fusion codon" consisting of two nucleotides derived from the MLL gene sequence and one from BTBD18 gene sequence. The chimeric protein of 1989 amino acids retains a major portion of MLL, including those domains known to be essential for leukemic transformation: the AT-hooks and the DNA methyltransferase domain (DNMT). The C-terminal sequences are derived from the BTBD18 protein, a new fusion partner. The fusion occurred with in the BTB/POZdomain of BTBD18 (Alonso et al., 2010).

KMT2A/BTBD18 KMT2A (11q23.3) BTBD18 (11q12.1) COF 2054 2055