RESUMO
Microsatellites are short tandem repeats of 1-6 bp DNA fragments, which are found throughout the genome. Due to their high levels of polymorphism, many of them are used as markers for population studies. Here we report an investigation on four microsatellites (D6S273, D6S2792, STR_MICA and D6S2810) located within the major histocompatibility complex in a sample of 281 Southern Brazilians of European ancestry. Allelic and haplotypic frequencies are described, as well as linkage disequilibrium (LD) between alleles of these microsatellites and alleles of three HLA genes: HLA-B, HLA-DRB1 and HLA-DQB1. The most polymorphic microsatellite was D6S2810, located close to the HLA-B locus. Strong LD was observed between alleles of microsatellites and HLA genes. The strongest associations occurred among STR_MICA*A5.1-HLA-B*13, STR_MICA*A6-HLA-B*49, STR_MICA*A9-HLA-B*39, STR_MICA*A9-HLAB*57, D6S2810*334-HLA-B*14, D6S2810*334-HLA-B*38, STR_MICA*A5.1-HLA-DRB1*1501-HLA-DQB1*0602 and D6S2810*344-HLA-DRB1*0411-HLA-DQB1*0302. This study contributes with important information on HLA haplotypes, and is potentially useful in resolving cases of low resolution HLA genotyping ambiguities.
Assuntos
Complexo Principal de Histocompatibilidade/genética , Repetições de Microssatélites/genética , Brasil , Frequência do Gene , Antígenos HLA-DQ/genética , Cadeias beta de HLA-DQ , Antígenos HLA-DR/genética , Cadeias HLA-DRB1 , Haplótipos , Heterozigoto , Humanos , Desequilíbrio de Ligação/genética , Glicoproteínas de Membrana/genética , Polimorfismo de Nucleotídeo Único/genética , População Branca/genéticaRESUMO
Bone marrow transplantation (BMT) is a therapeutic process used to treat a variety of hematologic diseases. After BMT, the documentation of engrafting with the use of genetic markers is obligatory. C-band polymorphism is an excellent genetic marker because it occurs with high frequency in all populations studied and shows a high stability in vitro and in vivo. We studied a total of 36 patients: 15 with myeloid leukemia and 21 with severe aplastic anemia (SAA), submitted to BMT. The majority of the patients with chronic granulocyte leukemia (CGL; 10/15, 67%) and with SAA (17/21, 81%) showed a frequency of host cells around 15% (CGL) and 8% (SAA) in the first period analyzed (day +30 post-BMT); with a decrease in the others (+90, +180 to CGL and SAA and +365 only to CGL). In our study, the persistence of host cells in these proportions did not imply an unfavorable prognosis. On the contrary, some patients with myeloid leukemia (5/15 33%) and SAA (4/21, 19%) showed high proportions of host cells in one or more periods analyzed. If compared to the first group, these patients had, in general, a poor clinical evolution, with rejections, relapses, and deaths in greater numbers. These results show the important contribution of cytogenetic analysis in the follow-up of patients submitted to BMT.
Assuntos
Transplante de Medula Óssea , Aberrações Cromossômicas , Leucemia Mielogênica Crônica BCR-ABL Positiva/genética , Adolescente , Adulto , Anemia Aplástica/genética , Criança , Feminino , Humanos , Leucemia Mielogênica Crônica BCR-ABL Positiva/terapia , Masculino , Pessoa de Meia-IdadeRESUMO
We report the first South American case of acute nonlymphocytic leukemia, French-American-British (FAB) subtype M1, [1] with trisomy 4 as the sole chromosome abnormality. The patient denied exposure to toxic or carcinogenic substances.