Genetic abnormalities

  • Chromosomal abnormalities are identified in around 50% of all adult patients with AML. Although some 40-50% of AML patients have no chromosomes abnormalities, they do have other gene mutations such as the FMS Like Tyrosine Kinase 3 (FLT3) gene and the nucleophosmin 1 (NPM1) gene.
  • AML genetic abnormalities, and the prognosis are shown in Table 2.

Table 2         Genetic abnormalities in AML and prognosis

GENETIC ABNORMALITIES IN AML PROGNOSIS
Chromosome abnormalities
Translocations
t(1;22) Good
t(3;3) or inv (3) Poor
t(6;9) Poor
t(8;21) Good
t(9;11)7 Intermediate
t(9;22) Poor
t(15;17) in APL Good
t(16;16) or inv (16) Good
Deletion/abnormalities of chromosome 5 or chromosome 7 Poor
Complex chromosome abnormalities in 3 or more chromosomes Poor
Gene abnormalities
ASXL1 (Additional sex combs-like 1) gene mutation Poor
FLT3-ITD (FMS‑Like Tyrosine Kinase-3 – internal tandem duplication gene mutation Poor
NPM1 (nucleophosmin 1) gene mutation with/without FLT3-ITD gene mutation Good
Non-mutated NPM1 with/without FLT3-ITD gene mutation Intermediate
RUNX1 (RUNX Family Transcription Factor 1) gene mutation Poor
RUNX1-RUNX1T1 fusion gene Good
TP-53 (tumour suppressor 53) gene mutation Poor

Inv (3) is an inversion of a section of chromosome 3. This may be inherited or a random mutation. Chromosome inversion is where a chromosome has been broken at two separate points, rotated by 180 degrees, and re-joined within the chromosome.

  • In chromosome abnormalities, the “t” stands for translocation. The numbers in brackets after the “t” are the numbers of the chromosomes involved in the translocation.
  • With a translocation, one part of a chromosome is transferred to another part of the same or a different chromosome. This results in a rearrangement of the genes within the newly-formed chromosome.

Genetic syndromes

  • Patients with syndromes due to genetic mutations are at increased risk of AML. These include:
  • Neurofibromatosis type 1 (condition where generally benign tumours grow along the nerves, causing a number of symptoms)
  • Down’s syndrome (extra copy of chromosome 21)
  • Trisomy 8 (extra copy of chromosome 8)
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