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In two patients with hematological neoplasias a tandem repetition of chromosome 21 in the bone marrow was revealed by cytogenetic analysis. The disease was different in the two patients: one was of the lymphoid type, acute lymphoblastic leukemia type L1, and the other was of the myeloid type, acute nonlymphoblastic leukemia type M2. In one case this chromosomal abnormality resulted in amplification of the AML1 gene (HUGO nomenclature: RUNX1), whereas in the other case the AML1 gene was not included in the tandem repetition, showing that apparently similar cytogenetic aberrations may be different at the molecular level.

We report herein a 38-year-old male patient with Fanconi anemia but with few phenotypic manifestations--short stature, sterility, and hypoplasic anemia with several years of evolution-who developed a myelodysplastic syndrome (MDS). Bone marrow karyotype showed long arm triplication of chromosome 1 (q12-21q31-q32), and two markers add(11)(p15) and add(21)(q22) which had extra material of chromosome 3 besides the normal chromosome 3 pair. Peripheral blood showed chromosome instability; SCE was normal. Both the patient and his family showed a high prevalence of malignant diseases. 1q duplication and, in a few cases, triplication of 1q has been related to Fanconi anemia, being of unknown significance.

We describe a family with an inherited fragile chromosome 16 with the concurrence of a constitutional chromosome abnormality, together with neoplastic pathology within the family. The following findings should be pointed out: in relation to the constitutional chromosome pathology, of the proband's 3 children, the eldest daughter was a carrier of the fragile 16, the same as the father, and the second child, a son, had Down syndrome (trisomy 21). Regarding the tumoral pathology of this family, one of the proband's daughters died in childhood from acute lymphoblastic leukemia, whereas the proband developed two different malignant hematologic disorders: a follicular lymphoma and an acute nonlymphocytic leukemia (M5 type). Moreover, two independent acquired chromosome disorders coexisted in the proband; each of these was related to one of the respective hematologic disorders.

A 51-year-old male patient was diagnosed with Burkitt lymphoma 3 months after cardiac transplantation. The bone marrow karyotype was very complex, and to better define the complex karyotype we used the in situ suppression hybridization technique. Previously we interpreted this karyotype to be: 48,XY,t(2;8)(p11;q24), +der(2)t(2;8)(p11;q24),del(2)(q23), +7, +der(8)t(2;8)(p11;q24), +12, -13, -18, by G banding techniques, with a duplication of the t(2;8) derivatives. After in situ hybridization we changed to a: 48,XY,t(2;8)(p11;q24),t(2;18)(q23;q22), +7, +der(8)t(2;8)(p11;q24), +12, -13, which implies duplication of only one t(2;8) derivative.

We report three cases of ANLL and one case of ALL in which we found chromosome abnormalities not previously described. The first patient had a (9;11;16)(p22;q23;p13) translocation in the relapse after bone marrow transplantation. In the second case, a secondary leukemia following a Wilms' tumor, there was a single chromosome anomaly, an inversion of chromosome 13. The third case also presented an isochromosome 13q. In the fourth patient we observed a translocation between two achrocentric chromosomes, as in the third patient, but not of the Robertsonian type: t(21;21)(q22.1;q22.5).

We describe the cytogenetic study of a neuroendocrine tumor of Merkel cells which appeared in a patient following a heart transplant. An abnormal karyotype was observed in a metastatic lymph node. The abnormality includes two markers derived from the long arm of chromosome 1, while maintaining two normal chromosomes 1.

A patient with a myelodysplastic syndrome and a 12q deletion was studied and followed-up. After 10 years and several cytogenetic studies, it is suggested that this abnormality can be the sole chromosomal change in myelodysplastic syndromes.

We describe a family with an inherited fragile chromosome 16 with the concurrence of a constitutional chromosome abnormality, together with neoplastic pathology within the family. The following findings should be pointed out: in relation to the constitutional chromosome pathology, of the proband's 3 children, the eldest daughter was a carrier of the fragile 16, the same as the father, and the second child, a son, had Down syndrome (trisomy 21). Regarding the tumoral pathology of this family, one of the proband's daughters died in childhood from acute lymphoblastic leukemia, whereas the proband developed two different malignant hematologic disorders: a follicular lymphoma and an acute nonlymphocytic leukemia (M5 type). Moreover, two independent acquired chromosome disorders coexisted in the proband; each of these was related to one of the respective hematologic disorders.

A 51-year-old male patient was diagnosed with Burkitt lymphoma 3 months after cardiac transplantation. The bone marrow karyotype was very complex, and to better define the complex karyotype we used the in situ suppression hybridization technique. Previously we interpreted this karyotype to be: 48,XY,t(2;8)(p11;q24), +der(2)t(2;8)(p11;q24),del(2)(q23), +7, +der(8)t(2;8)(p11;q24), +12, -13, -18, by G banding techniques, with a duplication of the t(2;8) derivatives. After in situ hybridization we changed to a: 48,XY,t(2;8)(p11;q24),t(2;18)(q23;q22), +7, +der(8)t(2;8)(p11;q24), +12, -13, which implies duplication of only one t(2;8) derivative.

A 40-year-old male was diagnosed with refractory anemia with excess blast in transformation; 11 months later, with the same hematologic situation, a cytogenetic study was carried out on bone marrow and a translocation between chromosomes 6 and 9 with breakpoints at p23 and q34, respectively, was found.

A patient diagnosed with chronic myeloid leukemia was studied periodically during his illness. The result showed the presence of a Philadelphia (Ph) chromosome by a 9;22 translocation as a single abnormality to the time of blastic crisis. At that time, the chromosome studies showed a clonal evolution. Furthermore, a second derivated line was added to the Ph line. This new anomaly consisted of a 8;21 translocation, considered as specific of M2 type acute nonlymphoblastic leukemia of French-American-British classification.

We report a case of acute myeloid leukemia (M5a of the FAB classification), secondary to the myelodysplastic syndrome, showing a deletion of the short arm of chromosome 2 at p23 in the bone marrow cells. In addition, a duplication of chromosome 13,dup(13)(q12q14) was found.