Cytogenetics in pre-B and B-cell acute lymphoblastic leukemia: a study of 208 patients diagnosed between 1981 and 2008.
The detection of chromosome abnormalities by conventional cytogenetics, now combined with analyses using fluorescence in situ hybridization (FISH), is an important component in assessing the risk stratification of acute lymphoblastic leukemia (ALL). Identification of specific chromosome abnormalities led to the recognition of genetic subgroups based on modal chromosomal number, reciprocal translocations in B-cell ALL, or both. We report here the cytogenetic analysis of 208 patients with pre-B and B-cell ALL referred to a single laboratory between 1981 and 2008. Chromosome abnormalities were observed in 82.9% of L1/L2 ALL patients and in 83.3% of L3 patients with successful analysis at diagnosis. The proportion of diploid karyotypes tended to decrease during the period of study, from 26% to 13%, in association with technical progress and the introduction of FISH techniques. As previously reported, the incidence of high hyperdiploidy (51-67 chromosomes) was higher among children, whereas pseudodiploidy and hypodiploidy were higher among those >15 years of age. Structural chromosome abnormalities were more frequently observed among patients older than 15 years than in children (75.9% vs. 68.5%, respectively). As previously reported, t(9;22)(q34;q11) and t(12;21)(p13;q21) were the most frequent structural rearrangements among adults (26.9%) and children (19.7%), respectively. Almost 17% of the patients studied at diagnosis had further cytogenetic analyses at relapse, the majority showing clonal evolution toward a more complex karyotype. Although the detection of chromosome abnormalities by conventional cytogenetics and FISH techniques is an important tool in assessing risk stratification of ALL, some patients lack abnormalities with clinical relevance. The use of array comparative genomic hybridization (aCGH) offers an alternative for identifying copy number alterations, but cannot detect balanced chromosomal rearrangements.
University of Western Brittany, Brest, France.
Etienne
E
De Braekeleer
Audrey
A
Basinko
Nathalie
N
Douet-Guilbert
Frédéric
F
Morel
Marie-Josée
MJ
Le Bris
Christian
C
Berthou
Patrick
P
Morice
Claude
C
Férec
Marc
M
De Braekeleer
D000293:Adolescent; D000328:Adult; D000368:Aged; D002869:Chromosome Aberrations; D011495:Histone-Lysine N-Methyltransferase; D006801:Humans; D015448:Leukemia, B-Cell / Q000235:genetics*; D008875:Middle Aged; D051788:Myeloid-Lymphoid Leukemia Protein / Q000235:genetics; D015452:Precursor B-Cell Lymphoblastic Leukemia-Lymphoma / Q000235:genetics*; D054198:Precursor Cell Lymphoblastic Leukemia-Lymphoma / Q000235:genetics*; D012008:Recurrence; D013997:Time Factors; D014178:Translocation, Genetic
C497422:KMT2A protein, human; D051788:Myeloid-Lymphoid Leukemia Protein; D011495:Histone-Lysine N-Methyltransferase