SIL-TAL1 , del(1p32)
TAL1 gene (T-cell acute leukemia gene 1) is normally expressed in pluripotent hematopoietic cells, mast cells, megakaryocytes and erythroid cell maturation, but never in lymphoid cells. About 30% of T-ALL carry aberrations in the TAL1 gene. Most of the time, about 25% of cases, this aberration consists of a 90 kb deletion in the chromosomal region 1p32. This deletion puts the TAL1 gene under the control of the SIL gene promoter, creating the chimeric gene SIL-TAL1. Three deletion points have been identified in the SIL gene (sildb1, sildb2 and sildb3) while TAL1 gene contains 7 deletion points (taldb1-taldb7). Both sildb1, taldb1 and taldb2 are in the majority of T-ALL cases (> 95% of cases).
Although aberrations in the TAL1 gene are the most common defects in T-ALL, no clear correlation is found between TAL1 gene aberrations and clinical outcome. However, one study suggested that the presence of SIL–TAL1 fusion genes is correlated with a good prognosis.
References:
- van der Burg M, et al. (2004) Leukemia 18, 895–908
- Cave H, Suciu S, et al. Blood (2003) 22: 22.
- Kikuchi A, Hayashi Y, et al. (1993) Leukemia 7: 933–938.
