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BACKGROUND: The prevalence of beta-thalassemia in Mexico is not known in detail. METHODS: Data of studies investigating abnormal hemoglobins between September 1987 and November 2000 were analyzed; in addition, data of red-blood-cell indices and clinical features were analyzed in patients identified as carriers of beta-thalassemia. RESULTS: In 1,639 prospective studies looking for abnormal hemoglobins, 429 disclosed some abnormality; of these, 319 cases displayed abnormally high levels of hemoglobin A2, thus consistent with the diagnosis of beta-thalassemia. This hemoglobin abnormality represented 74.2% of all abnormalities, both quantitative and qualitative, of the molecule of hemoglobin. There were 317 heterozygotes and only two homozygotes. We have previously shown that the most frequent cause of anemia as the iatrotropic condition in Mexican mestizos is iron deficiency. We found that iron deficiency is 11.5 times more frequent than beta-thalassemia and that the latter is 1.3 times more frequent than macrocytic/megaloblastic anemia. CONCLUSIONS: beta-thalassemia should not be considered as infrequent in Mexico, and individuals with red blood cell microcytosis and/or hypochromia with or without anemia should be screened for thalassemia.

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Chronic lymphocytic leukemia (CLL) is the most frequent leukemia in adults living in Western countries, and accounts for approximately 30% of adult leukemias. In a 15-year period in a single institution, we identified 19 patients with CLL in a group of 211 adults with leukemia (9% of adult leukemias). Of these 19 CLL patients, 8 had a Caucasian phenotype, 4 were born outside the country, and only 11 were Mexican mestizos. On the other hand, in a multicenter experience involving 1968 Mexican adults with leukemia, CLL represented 6.6% of the cases, a figure significantly lower than that reported in Caucasians (P < 0.01). CLL is the least frequent type of leukemia in Mexican mestizos, and this low prevalence may stem from the genetic origin of this racial group. The data also suggest a genetic predisposition of Caucasians to suffer from this disease.

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The distribution of abnormal hemoglobins in Mexico is derived from surveys and from the study of patients with hemolytic anemia. In aboriginal populations, more than 3,000 individuals have been studied: structural abnormal hemoglobins are virtually absent in Mexican Indians and the sporadic finding of hemoglobin S among them is due to admixture with Africans brought as slaves during the Spanish domination; two new variants of hemoglobin (Mexico and Chiapas) were found in aborigines. The surveys in hybrid groups in selected areas of the country show that in some West and East Coast communities there are different frequencies of Hb S heterozygous, and that a high prevalence of Hb S trait has been found in some communities similar to that in some African areas. In a group of 200 subjects of a town located along the Gulf of Mexico Coast, 6% of Hb S and 15% of thalassemia beta heterozygous is observed. In hospital surveys in two cities (Guadalajara and Puebla) several abnormalities of hemoglobin have been identified (C, SC, Riyadh, Baltimore, Tarrant, Fannin-Lubbock and Mexico). In the study of isolated cases, mainly of patients with hemolytic anemia, hemoglobins I-Philadelphia, G-San Jose and D-Los Angeles are seen. The thalassemias are the more frequent hemoglobin abnormalities in selected populations of our country. In a community of Italian ancestry a frequency of 1.3% of beta thalassemia trait is found. In our laboratory, 76% of the abnormalities are cases of beta thalassemia trait. Patients with Hb H disease, beta thalassemia (homozygous and heterozygous) and combinations of these abnormalities with hemoglobins S, Hb S + hereditary persistence of fetal hemoglobin (HPFH) and Hb E as well as families with delta-beta thalassemia, HPFH and Hb Lepore-Washington-Boston have been also detected.

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Two Mexican mestizo families with Hb Lepore Washington-Boston are described. One family is from Cordova, in the State of Veracruz, in the East coast of Mexico: the proband is a 44-year old asymptomatic male with italian ancestors; the other family is from the city of Durango, State of Durango, in the northwestern part of the country: the propositus is a 32-year old pregnant female with French ancestors. In both cases the Hb Lepore was identified by alkaline electrophoresis and characterized by high performance liquid chromatography and PCR with specific probes flanking the deletion frame. The beta-haplotype in both families was +(-)-(-)-(++), the commonest beta-haplotype reported with this mutation. This paper describes the first cases of this entity in Mexico.

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Two patients with hypergranular acute lymphoblastic leukemia are presented: they represent 1.4% of patients with acute lymphoblastic leukemia studied and treated in a single institution in the past 12 years. This frequency is substantially lower than that reported in Caucasian populations. The blast cells of the patients disclosed an early-B phenotype, displaying CD45, CD10 and CD19 antigens. The cytoplasmic granules were positive for the PAS reaction. Both patients died early after starting treatment; a poor prognosis has been recorded previously for patients with this type of malignancy.

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The prognosis and long-term results of a group of 57 acute megakaryoblastic leukaemia (M7-AML) patients was analysed from a multicentre perspective. Ages ranged from 4 to 83 years, median 49 years; 30 were males and 27 were females. The median follow-up time was 7 months, range 1-24 months. Early exits occurred in 12 cases, their median age being 71 years. Forty-five patients were treated with combined aggressive chemotherapy (CT) (n = 26) or low-dose cytarabine (LD-AraC) (n = 19). The following results were obtained with combined CT or AraC, respectively. Complete remission (CR) rates were 73% and 84%, 12-month survival (SV) were 37% and 26%, 24-month SV were 12% and 11%, median SV 10 and 4 months, and relapse rates (RR) were 68% and 94%. These differences were not statistically significant. Irrespective of the treatment modality, the results were better for children (n = 10) than for adults (n = 35): RR rates were 90% and 74%, median SV: 7 and 5 months, 12-month SV: 40% and 22%, 24-month SV; 30% and 9%, and RR: 78% and 81%, respectively; these differences also were not statistically significant. In addition, a literature review of 42 patients from 18 previous reports is presented, including seven cases treated with allogeneic bone marrow transplantation (BMT). The best results were obtained with BMT: 12 and 24 month SV was 86% and the RR was 0%. On the above-mentioned basis, we feel that children and young adults with M7-AML should be offered BMT. In patients over 60 years old or not eligible for aggressive chemotherapy or BMT, an interesting possibility would be the use of LD-AraC which allows a high CR rate, followed by a classical consolidation regimen in order to prevent early relapses.

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The first finding in the Mexican population of hemoglobin I-Philadelphia is described. Six members of a family in the state of Chiapas were found to have the trait.

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The prevalence of beta thalassemia (B-thal) in Mexico is largely unknown, and it is thought that the disease is confined to populations with Mediterranean ancestors. Various reports suggest that in certain parts of the coast in the Gulf of Mexico the prevalence of both B-thal and hemoglobin S disease/trait is high. We studied prospectively a town with 11,000 inhabitants named Tamiahua, located along the Gulf Coast, in the State of Veracruz, and very close to the State of Tamaulipas. A group of 200 inhabitants was initially studied: the prevalence of B-thal was 15% and 6% of them had sickle cell trait. The prevalence of B-thal is the highest reported in the country. In a second part of the study, two family trees with members heterozygous for B-thal and/or Hb S trait were constructed. The ethnic characteristics of the studied population makes unlikely that the gene was derived from white Europeans but not from black Africans. Inasmuch as the indians living in that part of the country belong to the macro-maya glotochronological group, where a relatively high prevalence of B-thal has also been identified, we feel that it is possible that B-thal was present in our country before the Spaniards arrived to Mexico.

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A 50-year-old female, heterozygous for beta-thalassaemia was found to have a lytic lesion surrounded by osteosclerotic tissue in the 1st lumbar vertebra. Aspiration of the lesion showed 100% atypical plasma cells. The bone marrow contained 17% myeloma cells. Despite normal electrophoresis and immunoelectrophoresis of serum and urine, 'rouleaux' formation was pronounced. Treatment of the serum sample with 2-mercaptoethanol and heat (56 degrees C) disclosed an uncommon pyroglobulin. Analysis of the ammonium sulphate precipitate of the serum by sodium-dodecyl-sulphate polyacrylamide gel electrophoresis revealed a 43 kD component with higher anodic mobility than normal gamma chains. Ultrafiltration column chromatography of the serum revealed a narrow spike of approximately 4 S that contained gamma heavy chain antigenic determinants in addition to normal 7 S IgG.

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Se informa del hallazgo en una familia mexicana de tres hermanos dobles heterocigotos para la hemoglobina E y la talasemia beta que padecen anemia hemolitica. Son originarios del centro del pais y no tienen ancestros asiaticos, africanos ni mediterraneos. Se estudiaron tres generaciones de la familia identificando varios heterocigotos para la hemoglobina E y la talasemia beta. La hemoglobina E no habia sido encontrada antes en Mexico y asociada a talasemia beta no tiene antecedentes en America Latina

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Se presenta el estudio familiar de una paciente con sangre incoagulable debido a ausencia congenita de fibrinogeno, asi como tambien la evolucion clinica de la nina. Su primera manifestacion hemorragica se observo en el periodo neonatal cuando presento sangrado de tres dias de duracion a la caida del cordon umbilical. Los eventos hemorragicos mas severos sufridos por esta paciente incluyeron una hemorragia epidural que requirio evacuacion con craniotomia parietal derecha y una hemorragia difusa del sistema nervioso central que determino su fallecimiento. En esta nina no se encontro fibrinogeno tiempo de sangrado prolongado, probablemente debido a que la agrecion plaquetaria requiere de la presencia de fibrinogeno

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We describe the gene markers found during the last 20 years in a private laboratory in the city of Puebla, Mexico. The greater proportion of our experience has to do with abnormal hemoglobins.

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