title: Trisomy 12 in B-cell chronic lymphocytic leukemia: interphase study by in situ hybridization in 75 patients.
abstract: Trisomy 12 is the most common cytogenetic abnormality in chronic lymphocytic leukaemia (CLL) and may be a prognostic indicator. In the present study, fluorescence in situ hybridization (FISH) is shown to be a method of choice for detection of trisomy 12 in interphase cells. Seventy-five cases of B-cell CLL were analysed with a chromosome 12 specific alpha satellite DNA probe and results compared with those from cytogenetic analysis. FISH showed the three hybridization spots characteristic of trisomy 12 in 32/75 patients (42.6%). Sixty-three patients were also studied by conventional cytogenetics: failure in 7 cases, normal karyotype in 28, trisomy 12 in 9 (14.3%) and in 19 cases abnormalities other than trisomy 12. In these same 63 patients, trisomy 12 was detected on 29 occasions by FISH (46%): in one case of failure by cytogenetic analysis, in 9 cases thought to have a normal karyotype, in 10 cases carrying abnormalities other than trisomy 12 and in all 9 cases showing trisomy 12 by conventional cytogenetic investigation. Correlation between trisomy 12 and the three stages of the Binet classification indicated an increasing proportion of trisomy 12 from stage A to stage C. It is concluded that fluorescence in situ hybridization is a powerful and sensitive technique for detection of trisomy 12 in CLL and although more cases will be required to confirm a correlation between the incidence of trisomy 12 and the stage of the disease, this link could be important from a prognostic point of view.
authors.affiliation: Département d'Hématologie, Hôpital Nord, Saint-Priest-en-Jarez, France.
authors.forename: L
authors.initials: L
authors.lastname: Coignet
authors.forename: M F
authors.initials: MF
authors.lastname: Berthéas
authors.forename: C
authors.initials: C
authors.lastname: Vasselon
authors.forename: J
authors.initials: J
authors.lastname: Jaubert
authors.forename: J
authors.initials: J
authors.lastname: Reynaud
authors.forename: P
authors.initials: P
authors.lastname: Calmard-Oriol
authors.forename: C P
authors.initials: CP
authors.lastname: Brizard
authors.forename: D
authors.initials: D
authors.lastname: Guyotat
mesh_terms: D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D002881:Chromosomes, Human, Pair 12; D005260:Female; D006801:Humans; D017404:In Situ Hybridization, Fluorescence; D015994:Incidence; D007399:Interphase / Q000235:genetics*; D007621:Karyotyping; D015451:Leukemia, Lymphocytic, Chronic, B-Cell / Q000235:genetics*; D008297:Male; D008875:Middle Aged; D014314:Trisomy