Cytogenetic analysis

Should be performed in all cases of acute leukaemia. It detects translocations and deletions that provide independent prognostic information in AML.

'Favourable risk' cytogenetics

• t(8;21)(q22;q22): FAB M2; 5-8% adults <55 years, rare older; fusion gene AML1/ETO.

• inv(16)(p13;q22) or t(16;16)(p13;q22): FAB M4Eo; 10% adults <45 years, rare older; fusion gene CBFp/MYH11.

• t(15;17)(q21;q11): FAB M3; 15% adults <45 years, rare older; fusion gene PML-RARa Variants: t(11;17)(q23;q11) fusion gene PLZF-RARa t(5;17)(q32;q11) fusion gene NPM-RARa t(11;17)(q13;q11) fusion gene NuMA-RARa

'Intermediate risk' cytogenetics

• Normal karyotype: any FAB type; 15-20% adults.

• abnormal 11q23*: >50% infant AML cases; 5-7% adults; fusion gene MLL.

• Others: del(9q)*; del(7q)*; +6; +21; +22; -Y and 3-5 complex abnormalities* plus other structural or numerical defects not included in the good risk or poor risk groups.

'Poor risk' cytogenetics

• -5/del(5q): any FAB type; >10% adults >45years.

• -7/del(7q): any FAB type; >10% adults >45 years.

• Complex karyotypes (>5 abnormalities*)

• Others: t(6;9)(p23;q34); t(3;3)(q21;q96); 20q; 21q; t(9;22); abn 17p. Note: This classification is based on the MRC-UK scheme1. Abnormalities marked * are classed as 'unfavourable' i.e. 'poor risk' in the scheme used by US Cooperative Groups2.

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