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Four children with mental deficiency and different chromosomal errors, previously reported, have been restudied with the use of the G-banding technique. The errors include ring-6, t(2q-; 15+), t(21q;21q) and 22q-.
A two years-old, severely mentally retarded male is reported with 22q trisomy. After the recent confirmation of the localisation of arylsulfatase-A (ARSA) on chromosome 22, the elevated activity of this enzyme (about 1,5 times the normal values) in the present patient may be another example of a gene dosage effect in autosomal imbalance.
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Cytogenetic studies of the bone marrow and peripheral blood with the quinacrine fluorescence banding technique in a patient with the clinical diagnosis of acute myeloblastic leukemia revealed the Philadelphia chromosome due to a translocation between chromosomes 22 and 9. He had been exposed to the atomic bomb in Hiroshima, and some hours after the exposure he wandered into the hypocenter.
Bone marrow (BM) karyotypes from 16 consecutive children presenting with nonlymphocytic leukemia were established with the use of banding techniques, before therapy. The two patients with chronic myeloid leukemia (CML) showed the Philadelphia (Ph1) translocation (9q+;22q-). Five of the 14 patients with an acute nonlymphocytic leukemia (ANLL) presented no acquired cytogenetic abnormalities, but one of these five showed a high level of hypodiploidy. One patient with AML evidenced a variant of the Ph1 chromosome originated as a translocation (12p+;22q-). Nonrandom abnormalities (-7; 7q-; +8; t(8;21); -21) were found in six patients, isolated or in association with otheraberrations. Among the random abnormalities, apparently balanced translocations and chromosomal deletions were observed. In ANLL, no correlation could be found between morphologic diagnosis and cytogenetic findings. On the other hand, the presence of BM cells with a normal karyotype at diagnosis was associated with an improved remission rate and survival time. Followup studies were performed in four ANLL patients with an abnormal cell clone at diagnosis. Three of them achieved hematologic remission; their BM karyotype was found to be normal at that stage. In the 4th patient, generalization of the abnormal karyotype in BM cells was seen in the terminal phase of the disease.
Basophilia is found in association with many diseases and is commonly seen in patients with chronic myelocytic leukemia (CML). Substantial basophilia development during the course of CML has been considered to be a poor prognostic sign. Prominent basophilia occasionally has been seen in patients at the time of the original diagnosis. These cases have been classified as "basophilic leukemia." A patient with a basophil count of 24,080/cu mm and myeloid immaturity in his peripheral blood had typical Ph1 chromosome in his bone marrow. G-banding studies showed typical 22q-;t(9q+;22q-) of CML. Since seven of the nine basophilic leukemias so far studied cytogenetically have Ph1 chromosomes and since Ph1 chromosomes are absent in the majority of eosinophilic leukemias, we believe it more appropriate to call basophilic leukemia basophilic CML.
A phenotypically normal donor for bone marrow transplantation was found to have a previously unreported karyotype, 46, XY, t(18q+;22q-), resulting in a Ph'-like chromosome. Identification of the Ph'-like chromosome in cultures of skin fibroblasts, phytohemaglutinin-stimulated peripheral blood cells, and bone marrow cells from the marrow donor, but not in cell cultures from siblings or parents, indicated that it represented an acquired somatic mutation. Demonstration of the Ph'-like chromosome in the marrow graft recipient's blood and bone marrow cells after transplantation provided a unique and definitive marker of engraftment. Hematopoiesis appeared normal in both the donor and recipient after transplantation. This study indicates that a mutation creating a Ph'-like chromosome in hematopoietic cells need not produce hematologic abnormality. Presence of this translocation did not appear to interfere with normal hematopoietic or lymphoid differentiation and replication in the transplant setting.
A patient with chronic myelogenous leukemia (CML) had a Philadelphia chromosome (Ph') [t(9q+;22q-)] in all cells and trisomy C in 13% of cells (later determined to be trisomy 8) at the time of diagnosis. After 21 months of intermittent treatment with busulfan, the acute phase developed with the appearance of an additional abnormality (trisomy ? 19). During a complete remission and reconversion to the chronic phase, trisomies 8 and ? 19 DISAPPEARed, although the Ph' remained. Following a period of marked thrombocytosis, a second relapse occurred with the reappearance of both marker chromosomes.
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.
The R-banding pattern of the chromosomes of 31 patients hospitalized in the Hematologic Clinic for myeloid leukemia were studied before chemotherapy. This analysis permitted identification of one unusual 3-chromosome rearrangement t(3;9;22) in addition to 25 classic forms of (22q-;9q+) translocation accompanied by the specific Ph' chromosome in chronic granulocytic leukemia patients, independent of the blastic course of the disease. During blastic crisis observed in 6 patients, extra 8 and 10 chromosomes, monosomy for chromosome 17, isochromosomes 17q, translocation (12q;13q), and additional Ph' were noted. The nonrandomness of these findings is determined from results published by other authors. Their significance for the cellular phenotype is presently unknown.
In a female patient with chronic myelocytic leukemia (CML) the translocation 9q +; 22q was constantly found to involve only the variant chromosome 9 with an unusually long secondary constriction. The finding indicates a unicellular origin of CML.
A girl is described, who, upon her first admission to our pediatric department in 1965, was supposed to have G-deletion syndrome II on the base of the chromosome findings in routine orcein-stained preparations and her clinical aspect. When, however, in 1972 a Q- and G-banding analysis was performed, the patient seemed to be a t(14q+; 22q-) translocation carrier. These findings are discussed in relation to the known heterogeneity of the clinical picture of patients previously reported as having a G-deletion syndrome and in whom no banding studies were done. Finally, the need for more extensive studies with the different techniques is stressed, particularly, in cases of Gq- chromosomes, of which the familial occurrence is suggestive of a hidden reciprocal translocation.
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.
Two children presented with Ph1-positive leukemia, confirmed by Giemsa banding as 22q-. One child showed an initial presentation characteristic of acute lymphoblastic leukemia, followed by development of chronic myelocytic leukemia 2 yr later. A second child presented in blast crisis. Both patients showed blast cells possessing both lymphoid and myeloid characteristics, as demonstrated by histochemical, biochemical, or surface receptor properties of each cell series. The evidence provided supports the assumption of mixed lymphoid-myeloid properties of blast cells in chronic myelocytic leukemia in children. Detailed study of the leukemic cells may aid in the understanding of complex stem cell relationships and suggest more effective therapeutic approaches.
The chromosome abnormalities associated with the classical type of chronic granulocytic leukaemia (CGL) involve a deletion of chromosome number 22 (Ph1) and translocation of the deleted material to another autosome, usually a number 9, t(9;22) (q34;q11). There is no clinically detectable difference between patients showing usual or unusual sites of translocation of 22q. In the chronic phase the typical translocation without additional abnormalities accounts for about two-thirds of the cases. Additional abnormalities include -Y and +8; difference of prognosis in association with aneuploidy has not yet been demonstrated. The presence of Ph1-negative cells in the chronic phase may be related to the time of ascertainment. The isochromosome for the long arm of number 17 is pathognomonic of impending metamorphosis. Additional chromosomal abnormalities are found in the majority of cases in the acute phase. Recent advances in immunological techniques for distinguishing different cytological types of blast cells, in patients who present with acute leukaemia with the Ph1 chromosome, have provided insight into the relationship of the Ph1 chromosome to the pathogenesis of the disease.
PURPOSE: The genomic architecture of 22q11.2 deletion syndrome (22q11.2DS) has primarily been studied in White populations, despite evidence suggesting a lower prevalence in Black individuals. This study aims to improve our understanding of the population-specific organization of 22q11.2 genomic structures. METHODS: Optical mapping data from 106 genomes, representing various Black and White individuals, were analyzed to assess the structure and variation of the 22q11.2 low copy repeats (LCR22s). RESULTS: Extensive variability in copy-number and orientation of LCR22 elements was observed between Black and White genomes. Several novel copy-number variants and haplotype configurations were identified, some being private or more prevalent within specific groups. Notably, copy-number variants diversity was particularly striking among Black genomes. Comparisons of Black and White families with de novo 22q11.2DS probands revealed unique nonallelic homologous recombination scenarios, with Black families exhibiting recombination patterns that are not previously observed. CONCLUSION: Perhaps the unique and highly variable LCR22 haplotype configurations in Black individuals contribute to the lower observed prevalence of 22q11.2DS by inhibiting the likelihood of nonallelic homologous recombination, the mechanism that leads to the syndrome.
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