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In MM, a chromosomal translocation between the immunoglobul<strong>in</strong> heavy cha<strong>in</strong><br />

gene on chromosome 14, locus q32 (14q32) and an oncogene 11q13 (cycl<strong>in</strong> D1), 4p16<br />

(FGFR3 & MMSET (Multiple Myeloma SET Doma<strong>in</strong>)), 6p21 (cycl<strong>in</strong> D3), 16q23 (c-<br />

maf), 20q11 (mafB) and 8q24 (mafA), which account for about 40% of all <strong>myeloma</strong><br />

tumors (Table 1.2), (Bergsagel and Kuehl, 2001; Barillé-Nion et al., 2003; Kyle and<br />

Rajkumar, 2004) is frequently observed. These mutations br<strong>in</strong>g about disregulation of<br />

the oncogenes that are known to be a significant <strong>in</strong>itiat<strong>in</strong>g event <strong>in</strong> the pathogenesis of<br />

MM. The consequence all of these mutations is proliferation of a plasma cell clone and<br />

genomic <strong>in</strong>stability that leads to further mutations, deletions and translocations.<br />

Table 1.2. Prevalance of Important Translocations <strong>in</strong> MM (Adapted from Sawyer et al.,<br />

1998; Kuehl and Bergsagel, 2002; Avet-Loiseau et al.,2002).<br />

Translocations Prevalance<br />

11q13 (cycl<strong>in</strong> D1) 15%<br />

4p16 (FGFR3 & MMSET) 15%<br />

6p21 (cycl<strong>in</strong> D3) 3%<br />

16q23 (c-maf) 4%<br />

20q11 (mafB) 2%<br />

8q24 (mafA) 1%<br />

TOTAL 40%<br />

Translocations between t(4;14) (p16;q32) or t(14;16) (q32;q23), partial (q14) or<br />

complete loss of chromosome 13 and partial loss of 17p13 refer to high risk of MM<br />

(Stewart and Fonseca, 2005; Tassone et al., 2006). In addition to these data,<br />

translocation t(11;14) (q13;q32) that is activated Bcl-1 oncogene is the most common<br />

chromosomal difference (Stewart, 2008). This translocation is also seen <strong>in</strong> other<br />

hematological cancers. Besides, <strong>changes</strong> <strong>in</strong> the number of chrosomes are frequently<br />

encountered <strong>in</strong> MM, especially hyperdiploidy is seen at the 3., 5., 7., 9., 11., 15., 19.<br />

and 21. chromosomes whereas hypodiploidy is seen at the 8., 13. and X chromosomes<br />

(Gahrton and Durie, 1996; Mah<strong>in</strong>dra et al., 2010).<br />

In MM, the chromosome 14 abnormality is observed nearly 50% of all cases of<br />

<strong>myeloma</strong> and aberration of chromosome 13 is also observed <strong>in</strong> about 50% of cases with<br />

85% monosomy 13, while the rema<strong>in</strong><strong>in</strong>g 15% constitute deletion of chromosome 13<br />

(Munshi and Avet-Loiseau, 2011; Sawyer, 2011).<br />

9

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