RESUMO
Chromosome 1 C-band length mosaicism was detected in lymphocytes from six tumor patients and one healthy subject belonging to three families with a high incidence of cancer. In all cases the variant cell population showed a decreased amount of C-heterochromatin in one chromosome, whereas the C-banded pattern of the homolog was identical to that of the nonvariant cell population. A family tendency to unequal mitotic crossing over, possibly leading to C-band heteromorphism, may explain the high frequency of detection of C-heterochromatin mosaicism in cancer family members (seven of 13 cases studied). The possible role of heterochromatin in inducing cancer has been widely discussed. The special feature of the acquired C-band variants vis-à-vis the inherited ones is that they mark intrinsic genetic instability that may result, through multiple mechanisms, in increased susceptibility to malignancy.
Assuntos
Cromossomos Humanos Par 1 , Mosaicismo , Síndromes Neoplásicas Hereditárias/genética , Idoso , Bandeamento Cromossômico , Feminino , Heterocromatina/genética , Heterocromatina/ultraestrutura , Humanos , Cariotipagem , Linfócitos/ultraestrutura , Masculino , Pessoa de Meia-Idade , LinhagemRESUMO
Ten leiomyosarcomas (LMS) affecting the same patient over a period of 3 years were cytogenetically studied to detect nonrandom chromosomal changes with a pathogenetic significance. All tumors, likely metastases of a previous LMS presentation, were classified as small, including eight that developed before chemotherapy; the diagnoses were based on standard immunohistochemistry methods for smooth muscle tumors. Scoring of 613 metaphases revealed monosomy of chromosome 22 in six LMS, monosomy of chromosome 19 in three, and deletion of chromosome 19p in all ten. Interphase fluorescence in situ hybridization (FISH) of the 22-alphoid-specific probe allowed loss of the target chromosome to be detected in four tumors at higher frequencies than those detected by cytogenetics. Double-color FISH of the 19p- and 19q-specific YAC performed on one tumor made it possible to distinguish the monosomic and 19p deleted cells, the relative frequencies of which were found to be 10% and 20%, respectively. The deletion breakpoint could be mapped at 19p13 between YAC 957d12 and YAC 947g4. The recurrence of the 19p deletion in a subset of tumor cells from all of the analyzed LMS suggests that this structural aberration is a significant change in the development of leiomyosarcomas.
Assuntos
Deleção Cromossômica , Cromossomos Humanos Par 19/ultraestrutura , Hibridização In Situ/métodos , Leiomiossarcoma/genética , Segunda Neoplasia Primária/genética , Neoplasias de Tecidos Moles/genética , Adulto , Biomarcadores Tumorais/análise , Cromossomos Humanos Par 19/genética , Humanos , Cariotipagem , Leiomiossarcoma/química , Leiomiossarcoma/patologia , Masculino , Repetições de Microssatélites , Proteínas de Neoplasias/análise , Recidiva Local de Neoplasia , Segunda Neoplasia Primária/química , Segunda Neoplasia Primária/patologia , Neoplasias de Tecidos Moles/química , Neoplasias de Tecidos Moles/patologiaRESUMO
The uncommon case is described of a girl severely affected with Duchenne muscular dystrophy. Cytogenetic analysis revealed no numerical or structural abnormalities of the X-chromosome in any of the cells examined (leucocytes and myoblasts). No abnormality in morphology, growth pattern or differentiation was observed in the dystrophic muscle cultures as compared with control cultures.