Candidate gene association study conditioning on individual ancestry in patients with type 2 diabetes and metabolic syndrome from Mexico City.

BACKGROUND: Type 2 diabetes (T2D) is influenced by diverse environmental and genetic risk factors. Metabolic syndrome (MS) increases the risk of cardiovascular disease and diabetes. We analysed 14 cases of polymorphisms located in 10 candidate loci, in a sample of patients with T2D and controls from Mexico City. METHODS: We analysed the association of 14 polymorphisms located within 10 genes (TCF7L2, ENPP1, ADRB3, KCNJ11, LEPR, PPARgamma, FTO, CDKAL1, SIRT1 and HHEX) with T2D and MS. The analysis included 519 subjects with T2D defined according to the ADA criteria, 389 with MS defined according to the AHA/NHLBI criteria and 547 controls. Association was tested with the program ADMIXMAP including individual ancestry, age, sex, education and in some cases body mass index (BMI), in a logistic regression model. RESULTS: The two markers located within the TCF7L2 gene showed strong associations with T2D (rs7903146, T allele, odd ratio (OR) = 1.76, p = 0.001 and rs12255372, T allele, OR = 1.78, p = 0.002), but did not show significant association with MS. The non-synonymous rs4994 polymorphism of the ADRB3 gene was associated with T2D (Trp allele, OR = 0.62, p = 0.001) and MS (Trp allele, OR = 0.74, p = 0.018). Nominally significant associations were also observed between T2D and the SIRT1 rs3758391 SNP and MS and the HHEX rs5015480 polymorphism. CONCLUSIONS: Variants located within the gene TCF7L2 are strongly associated with T2D but not with MS, providing support to previous evidence indicating that polymorphisms at the TCF7L2 gene increase T2D risk. In contrast, the non-synonymous ADRB3 rs4994 polymorphism is associated with T2D and MS.

An economic model of haemophilia in Mexico.

A model was developed to assess the lifetime costs and outcomes associated with haemophilia in Mexico. A retrospective chart review of 182 type A haemophiliacs was conducted for patients aged 0-34 years receiving one of three treatments: (i) cryoprecipitate at clinic; (ii) concentrate at home; or (iii) concentrate at clinic. Patients treated at home experienced 30% less joint damage, used 13-54% less factor VIII, had four times fewer clinic visits, and utilized half as many hospital days than those treated at a clinic. For cryoprecipitate at clinic patients, the annual incidence rates of HCV and HIV were calculated to be 3.6% and 1.4% respectively. The life expectancy for patients receiving cryoprecipitate and those receiving concentrate was estimated to be 49 years and 69 years respectively, with 58% of cryoprecipitate patients predicted to die of AIDS before age 69. Across the lifespan, the average annual cost of care was US$11,677 (MN$110,464) for cryoprecipitate at clinic patients, US$10,104 (M$95,580) for concentrate at home patients and US$18,819 (MN$178,027) for concentrate at clinic patients. Using a 5% discount rate, the incremental lifetime cost per year of life added for treatment with concentrate at home compared with cryoprecipitate at a clinic was US$738 (MN$6981). Rank order stability analysis demonstrated that the model was most sensitive to the cost of fVIII. These results indicate that treatment with concentrate at home compared with cryoprecipitate at a clinic substantially improves clinical outcomes at reduced annual cost levels.

Germline origins in the human F9 gene: frequent G:C-->A:T mosaicism and increased mutations with advanced maternal age.

The factor IX gene (F9) is an advantageous system for analyzing recent spontaneous germline mutation in humans. Herein, the male:female ratio of mutation ("r") in F9 have been estimated by Bayesian analysis from 59 germline origin families. The overall "r" in F9 was estimated at 3.75. The "r"s varied with the type of mutation. The "r"s ranged from 6.65 and 6.10 for transitions at CpG and A:T to G:C transitions at non-CpG dinucleotides, respectively, to 0.57 and 0.42 for microdeletions/microinsertions and large deletions (>1 kb), respectively. The "r" for the two subtypes of non-CpG transitions differed (6.10 for A:T to G:C vs 0.80 for G:C to A:T). Somatic mosaicism was detected in 11% of the 45 origin individuals for whom the causative mutation was visualized directly by genomic sequencing of leukocyte DNA (estimated sensitivity of approximately one part in 20). Four of the five defined somatic mosaics had G:C to A:T transitions at non-CpG dinucleotides, hinting that this mutation subtype may occur commonly early in embryogenesis. The age at conception was analyzed for 41 US Caucasian families in which the age of the origin parent and the year of conception for the first carrier/hemophiliac were available. No evidence for a paternal age effect was seen. However, an advanced maternal age effect was observed (P=0.03) and was particularly prominent for transversions (average of the 79th percentile when maternal age was normalized for the year of conception). This suggests that an increased maternal age results in a higher rate of transmitted mutation, whereas the increased number of mitotic replications associated with advanced paternal age has little, if any, effect on the rate of transmitted mutation.

Molecular epidemiology of factor IX germline mutations in Mexican Hispanics: pattern of mutation and potential founder effects.

Germline mutations in patients with hemophilia B generally have arisen within the past 150 years. Evidence suggests that these germline mutations generally result from endogenous processes. However, a unique pattern would be expected if a population were exposed to a physiologically important germline mutagen since mutagens generally produce characteristic patterns, or "fingerprints", of mutation. To determine the pattern of mutation in Mexican Hispanics, the regions of likely functional significance in the factor IX gene were screened by dideoxy fingerprinting (ddF) in 31 families with hemophilia B. Mutations were found in 30 of these families. Haplotype analysis was performed on individuals with identical mutations to help distinguish independent, recurrent mutations from founder effects. Analysis of these 30 mutations, along with 7 mutations reported previously in Mexican Hispanic families, reveals a pattern of independent mutation that is similar to the pattern of mutation observed in 127 U.S. Caucasian families (p = 0.89). These results may reflect either an underlying pattern of germline mutation due to endogenous processes or the presence of an ubiquitous mutagen. Further analyses of the recurrent mutations revealed that two mutations, T296M and R248Q, accounted for 19% of the mutations found in the Mexicans. Haplotype data suggest that the multiple occurrences of T296M and R248Q are associated with founder effects and that screening for these mutations may allow rapid mutation detection and carrier diagnosis in a significant minority of Mexican families with hemophilia B, These two mutations also are associated with founder effects in the U.S, Caucasian population. However, the haplotypes are different in these two populations, indicating independent origins. The occurrence of identical founder mutations in distinct populations provides evidence for the previous hypothesis that the number of different mutations giving rise to mild or borderline mild/moderate hemophilia B is small compared to deleterious mutations causing more severe disease.

Prothrombin "Mexico City," an asymptomatic autosomal dominant prothrombin variant.

A functionally normal but structurally abnormal prothrombin variant was found in a Mexican family. Immunoisoelectricfocusing studies revealed that this variant has a more acidic isoelectric point (4.01) than normal prothrombin (4.29), but it proved to have a normal molecular weight as assessed by sodium-dodecyl-sulphate polyacrylamide gel electrophoresis. Two-dimensional immunoelectrophoresis studies showed an abnormal cleavage of the prothrombin molecule by factor Xa and Echis carinatus venom as well, despite the fact that both yield functionally normal thrombin molecules. Finally, the ability of the molecule to bind calcium ions as well as its overall antigenic structure were investigated and found to be normal. These results taken together suggest a simple (substitution or translocation) mutation at the fragment 2 level. Since this prothrombin variant is different from others described previously, the name "Mexico City" is proposed to identify it.

Low-dose autologous in vitro opsonized erythrocytes. Radioimmune method and autologous opsonized erythrocytes for refractory autoimmune thrombocytopenic purpura in adults.

Adult patients with chronic autoimmune thrombocytopenic purpura (ATP), which proved refractory to various treatments, received a single dose of autologous in vitro opsonized erythrocytes with 100 micrograms of anti-D IgG. In 1983, 30 of these patients were treated with autologous erythrocytes that had been opsonized and labeled with 25 mCi (740 MBq) of technetium Tc 99m; this treatment was designated as the radioimmune method. Favorable responses were noted in 36% of patients so treated. In 1985, another group of 16 patients with refractory ATP received therapy with autologous opsonized erythrocytes (AOPE) and 55% of these patients showed favorable responses. Five (17%) of the patients treated using the radioimmune method attained a complete, long-term (greater than 35 months) remission of their ATP, and five (31%) of the patients treated using AOPE remained in complete remission over 270 days after cessation of therapy. Major complications were not seen. We concluded that the interaction of macrophages with low-dose AOPE is a successful therapeutic approach in ATP refractory to standard treatment.

Therapeutic effect of danazol on metrorrhagia in patients with idiopathic thrombocytopenic purpura (ITP).

Idiopathic thrombocytopenic purpura (ITP) is more frequently seen in young females than in any other age or sex group. Danazol, an impeded androgen with a decreased masculinizing potential, has been described as useful in ITP. A total of 25 women 16 to 41 years of age, with chronic ITP were studied. All patients were refractory to treatments with glucocorticoids and splenectomy; 19 were inadequately controlled by immunosuppressants, vinblastine or vincristine-loaded platelets, the radioimmune method, colchicine, plasmapheresis, or surgery for accessory spleens. Danazol was given at a daily dosage of 600 mg for 4 months. All showed clinical improvement, as indicated by cessation or decrease of bleeding, and 12 (48%) cases obtained a drug-dependent excellent or good response of their ITP. Therapy produced amenorrhea or oligomenorrhea in 21 patients (84%) and 7 cases of chronic metrorrhagia were successfully controlled. The drug was well tolerated. Accordingly, danazol may be an effective treatment for ITP or related conditions, especially in adult females with uncontrollable metrorrhagia.

Therapeutic experience on 934 adults with idiopathic thrombocytopenic purpura: Multicentric Trial of the Cooperative Latin American group on Hemostasis and Thrombosis.

In order to analyze the usefulness of different types of treatment in relation to the interval since the onset of idiopathic thrombocytopenic purpura (ITP), a collaborative study of 934 adult patients was undertaken. Prednisone was administered to 818 patients, and 32% of them achieved prolonged complete remission (PCR). However, only 14% of patients who had ITP for more than six months achieved a prednisone-induced PCR (P less than .01). Splenectomy was done in 399 patients, and 65% of them achieved PCR; the remission rate did not vary with the interval since the onset of ITP. Of 120 patients with chronic ITP that was refractory to corticosteroids and splenectomy, 91 received either azathioprine or cyclophosphamide; 21% of them achieved PCR and 55% had a favorable response. None of 19 patients treated with vincristine and only one of ten patients treated with vinblastine-loaded platelets achieved PCR.

Hepatic injury during doxorubicin therapy.

Six patients with acute lymphoblastic leukemia manifested liver dysfunction related to doxorubicin hydrochloride therapy. Other causes, eg, infection, hepatitis, posttransfusion reaction, and leukemic infiltration were ruled out. There was close correlation between the administration of doxorubicin and the appearance of hepatic dysfunction. Doxorubicin may produce an idiosyncratic reaction and must be considered a drug with potential liver toxicity.

Treatment of adult acute lymphoblastic leukemia with adriamycin, vincristine, and prednisone.

At the present time, it is possible to achieve up to a 95% complete remission in childhood acute lymphoblastic leukemia, using the combination of vincristine and prednisone. Nevertheless, it has not been possible to reproduce these results in the adult. For this reason, a third drug, in this case adriamycin in a low dose, was added to the vincristine-prednisone combination in the treatment of adult acute lymphoblastic leukemia (ALL). Complete remission was achieved in 45 of the 50 patients (90%). The median duration of remission was 23 months and the median survival time in this group was 31 months. The complications were minimal and the tolerance was good. From the point of view of our results and others reported in the literature, we consider that the combination of vincristine, prednisone, and adriamycin is a useful method for induction of remission of adult ALL.

Use of heparin for cytapheresis and plasmapheresis in a continuous flow centrifuge.

We evaluated the use of heparin in continuous flow centrifugation by continuous infusion. Doses were modified by assessment of the anticoagulant effect by the thrombin time dilution test (TTDT). Heparin is an efficient anticoagulant in continuous flow centrifugation and the TTDT is an effective and reliable method for control. The initial dose in leukapheresis is one unit per milliliter of blood during the first hour, then one-half the dose during the next hour, and then a one-quarter of the dose until the procedure is completed. A TTDT performed every 30 to 60 minutes will indicate whether the heparin dose should be modified. For plasmapheresis, it is necessary to determine the specific dose for each patient. There was no case of bleeding or extracorporeal coagulation of the blood.