A case of chronic myeloid leukemia with a translocation (12;22)(p13;q11)

Translocation (12;22)(p13;q12) as sole karyotypic abnormality in a patient with nonlymphocytic leukemia

Cytogenetic analysis of unstimulated bone marrow (BM) and peripheral blood (PB) cells of a patient with clinical features of atypical chronic myeloid leukemia (CML) showed t(12;22)(p13;q12) as the sole karyotypic abnormality. Subsequent fluorescence in situ hybridization (FISH) with abl- and bcr-specific cosmids as well as chromosome 12- and 22-specific DNA libraries and Southern blot analysis confirmed that in this patient t(12;22) does not constitute a cryptic Ph variant. Recently, a few very similar cases were reported by other investigations. The possible significance of this translocation as a new cytogenetic marker for nonlymphocytic leukemia is discussed.

Genomic diversity of Philadelphia-positive chronic myelogenous leukemia

The incidence of breakpoints in CML patients with variant translocations was investigated. There was no relationship between the length of various chromosomes with breakpoint frequency. However, a significantly higher (p less than 0.05) incidence of breaks were seen on the long arms as compared to the short arms due mainly to the involvement of 9q and 22q in these translocations. Chromosome 17 showed a significantly (p less than 0.005) higher involvement in these translocations, however only when 9q34-qter was not cytogenetically involved. A total of 683 breaks were found in 225 cases. 362 of these were located at c-abl and c-sis, while 110 were at other oncogenetic sites. The prognostic and hematologic features of patients with variant translocations are not significantly different from those of CML cases with the typical 9q;22q translocation. Some of these complex translocation, where the breakpoints are correlated with oncogenetic sites, are further discussed in molecular terms.

Unusual translocations involving chromosomes 12;22 and 9;12 in a case of chronic myelogenous leukemia

A case of chronic myelogenous leukemia (CML) with highly unusual translocations involving both chromosomes #12 is reported. The origin of the Ph1 chromosome was due to a 12p/22q translocation. Chromosome #9 was involved in a translocation with the other chromosome #12. By critical examination of the "size" of the Philadelphia chromosome, it was noted that the breakpoints on 22q were different when compared with a previous case (see Verma and Dosik [16]), although the short arm of chromosome #12 (12p) was involved in both instances. So far, no apparent differences in the course of the disease have been attributed to the types of translocation observed in these cases.

"Masked" philadelphia chromosome (Ph1) due to an unusual translocation

The case of a 58-year-old white female with Philadelphia (Ph1)-positive chronic myelocytic leukemia (CML) and a "masked" Ph1 chromosome is described. The Ph1 was due to a translocation involving chromosomes #12 and #22, in which most of the long arm of #12 had been translocated to the deleted #22 (Ph1). The necessity of performing banding analysis in those cases of CML where a Ph1 is not readily apparent is stressed and the literature on"masked" Ph1 chromosomes is briefly summarized.

New translocations in chronic granulocytic leukaemia: t(X;22)(p22;q11) and t(15;22)(q26;q11)

Two cases of Ph1-positive chronic granulocytic leukaemia with hitherto undescribed translocations are presented. In case 1 the deleted part of chromosome number 22q- was translocated to the short arm of the X chromosome, t(X;22)(p22;q11). Pronounced basophilia, trisomy 19 in the majority of metaphases, and a partial cytogenetic normalization of the bone marrow during busulphan induced remission were additional remarkable features of this case. In case 2 a translocation t(15;22)(q26;q11) was found. In this case the disease was characterized by an increase of unusually small megakaryocytes, thrombocytosis, and an accelerated course.

Three chromosomes' (7;9;22) rearrangement and the origin of the Philadelphia chromosome

A woman with chronic myelocytic leukemia had the Philadelphia chromosome and a complex four-break--three-chromosome rearrangement. The q32 leads to q34 portion of chromosome 9 is translocated to band q22 of chromosome 7, and at the end of this segment is attached the deleted q11 leads to qter portion of chromosome 22. A review of 12 cases of the Philadelphia chromosome originating by the rearrangement of three or more chromosomes reveals that chromosomes 9 and 22 are always involved, while the third chromosome is a different one in each case. We discuss the hypothesis that the 22q segment is always specifically attached to band 9q34 wherever this portion of 9q is transposed.