MALT1/API2 and MALT1/IgH

(Mucosa-Associated Lymphoid Tissue lymphoma translocation gene 1)

MALT1 is a paracaspase of unknown function. Wild-type API2 inhibits the action of several caspases and inhibits apoptosis4.

The MALT1/API2 t(11;18) (q21;q21) translocation is the most frequent in extranodal marginal zone lymphoma1,2, being found in 30% to 50% of MALT lymphomas of various sites4 and being particularly common in gastric and pulmonary MALT lymphomas, with moderate frequency in ocular adnexal MALT lymphomas but is rare at sites such as salivary gland, thyroid, skin, liver and other rare sites6. In the stomach, it is associated with loss of dependence on stimulating H pylori-specific T-cells and therefore with resistance to anti-Helicobacter therapy3. The alternative translocation, MALT1/IgH involved the immunoglobulin heavy chain. Both translocation can be demonstrated by FISH, with a break-apart probe able to detect either.

The t(11;18) (q21;q21) translocations is associated with upregulation of bcl-104.

H. pylori gastritis (without lymphoma) lacks the MALT1/API2 translocation.

The t(14;18)((q32;q21) translocation results in a MALT1/IgH fusion. There are often other additional chromosomal abnormalities but the t(14;18)((q32;q21) and t(11;18) (q21;q21) translocations are mutually exclusive. This translocation has been identified in MALT lymphomas of the skin, liver, ocular adnexa and salivary gland5.

Diagnostic utility

References

1 Akagi T, Motegi M, Tamura A, et al. A novel gene, MALT1 at 18q21, is involved in t(11;18) (q21;q21) found in low-grade B-cell lymphoma of mucosa-associated lymphoid tissue. Oncogene 1999; 18:5785-94

2 Auer IA, Gascoyne RD, Connors JM, et al. t(11;18)(q21;q21) is the most common translocation in MALT lymphomas. Ann Oncol 1997; 8:979-85

3 Liu H, Ruskon-Fourmestraux A, Lavergne-Slove A, et al. Resistance of t(11;18) positive gastric mucosa-associated lymphoid tissue lymphoma to Helicobacter pylori eradication therapy. Lancet 2001; 357:39-40

4 Liu H, Ye H, Dogan A, et al. T(11;18)(q21;q21) is associated with advanced mucosa-associated lymphoid tissue lymphoma that expresses nuclear BCL10. Blood 2001; 98:1182-7 FULL TEXT

5 Streubel B, Lamprecht A, Dierlamm J, et al. T(14;18)(q32;q21) involving IGH and MALT1 is a frequent chromosomal aberration in MALT lymphoma. Blood 2003; 101:2335-9 FULL TEXT

6 Ye H, Liu H, Attygalle A, et al. Variable frequencies of t(11;18)(q21;q21) in MALT lymphomas of different sites: significant association with CagA strains of H pylori in gastric MALT lymphoma. Blood 2003; 102:1012-8 FULL TEXT

This page last revised 17.11.2006.