HLA-DRB1 alleles are associated with the clinical course of disease and steroid dependence in Mexican patients with ulcerative colitis

AIM

The aim of this study was to study the association between the HLA-DRB1 alleles and the clinical course of ulcerative colitis (UC).

METHOD

  Seventy-five Mexican patients with UC were studied. High resolution HLA typing was performed using Polymerase Chain Reaction-Sequence Specific Oligonucleotide PCR-SSO reverse dot blot and Polymerase Chain Reaction-single specific primer PCR-SSP. Molecular typing techniques were applied to define HLA-DRB1 alleles.

RESULTS

Seventy-five patients (36 female patients, 39 male patients) were studied. Significant associations were found between some HLA-DRB1 alleles and the clinical course of disease: initial active and then inactive and the HLA-DRB1*14 allele (P = 0.03; OR = 4.63; 95% CI: 1.08-21.23); and HLA-DRB1*08 allele (P = 0.04; OR = 4.34; 95% CI: 1.9-33.3). On the other hand, the HLA-DRB1*07 (P = 0.001; OR = 9.76 95% CI: 1.55-65.56) was significantly associated with steroid dependence in UC patients.

CONCLUSIONS

 This study suggests that HLA-DRB1 alleles were associated with the clinical course of disease and steroid dependence in UC patients.

Human leukocyte antigen typing in tuberculous rheumatism: Poncet's disease

SETTING

Tuberculous rheumatism (Poncet's disease) is a reactive polyarthropathy associated with extra-pulmonary and pulmonary tuberculosis (TB) without evidence of mycobacterial infection of the involved joints. As all patients with TB do not present with this peculiar clinical feature, a genetic susceptibility is suspected.

OBJECTIVE

To determine the major histocompatibility complex (MHC) class I and II alleles in Mexican mestizo patients with Poncet's disease.

DESIGN

In this case-control study of 16 Mexican mestizo patients diagnosed with Poncet's disease and 99 ethnically matched healthy controls, high resolution human leukocyte antigen (HLA) typing was performed for HLA-A, B, DR and DQ by polymerase chain reaction. HLA-DRB1 and HLA-DQB1 subtypes were performed by sequence-specific oligonucleotide probe hybridization.

RESULTS

A significantly increased frequency of HLA-B27 (corrected P = 0.01) and DQB1*0301 (corrected P = 0.0009) alleles and decreased frequency of HLA-DQB1*0302 (corrected P = 0.00001) were identified in patients compared to healthy controls.

CONCLUSION

These data suggest that genes located within the MHC may play a role in the susceptibility to Poncet's disease in patients diagnosed with TB.

Clinical evolution of heart transplantation in patients with previous valvular cardiomyopathy

OBJECTIVE

Heart transplantation (HT) due to valvular cardiomyopathy is rare, namely, about 3% of cases in the Registry of the International Society for Heart and Lung Transplantation (ISHLT). Usually, these patients present some risk factors such as previous valvular operations and pulmonary hypertension. Since there are few studies in the literature, we retrospectively analyzed our early and long-term results.

MATERIALS AND METHODS

We studied our experience in 22 HT cases for valvular cardiomyopathy (9.3% of our total experience), namely, 12 men and 10 women, of overall mean age of 52.6 +/- 10 years. Five patients had mitral; 8, aortic; and 1, tricuspid valve disease; 7 had double valve disease and 1, triple valve disease. Nineteen patients (87%) had been operated previously between 1 and 4 times. The mean ejection fraction was 23% +/- 7.3% and the mean New York Heart Association (NYHA) functional class was 3.7. Fifty-three percent of the patients had pulmonary hypertension. Two patients were operated as an emergency "O." We used the standard HT technique.

RESULTS

Four patients (18%) were reoperated due to hemorrhage. The hospital mortality was 2 cases (9%). Another patients (9%) died on follow-up due to cardiac allograft vasculopathy. All surviving patients have been followed to the end of 2006. The mean follow-up has been 72 +/- 53 months. They are functional class I or II.

CONCLUSIONS

HT for this indication was more frequent in our experience than in the Registry of the ISHLT. The immediate and long-term results were good, with an 82% mean survival at 6 years. HT can be a good treatment for patients with valvular cardiomyopathy and bad ventricular function and/or multiple valvular reoperations.

HLA-DRB1*0101 is associated with the genetic susceptibility to develop lichen planus in the Mexican Mestizo population

The etiology of lichen planus (LP) is still unknown and previous studies have found an association between LP and HLA-DR1, DR2, DR3, DR9 and DR10 in different populations. The aim of this study was to analyze the distribution of the HLA-DRB1 alleles in Mexican Mestizo patients with LP. The aim of this study was to determine the gene frequency of HLA-DR locus in Mexican Mestizo patients with LP. We studied 20 patients with LP and 99 healthy Mexican Mestizo controls. HLA-DRB1 was performed by PCR-SSO reverse dot blot hybridization. High resolution HLA typing was performed by PCR-SSP. The HLA-DRB1*0101 allele was associated significantly in LP patients compared with healthy controls (pC = 0.0007, OR = 5.46, 95% CI = 1.86-16.06). HLA-DRB1*0101 is a marker for the development of LP in Mexican Mestizo population, yet another gene or HLA marker within MHC region may be the causatively associated gene.

P2X7 and NRAMP1/SLC11 A1 gene polymorphisms in Mexican mestizo patients with pulmonary tuberculosis

Tuberculosis remains one of the most important infectious diseases worldwide. Several studies have suggested that genetic factors may affect susceptibility to tuberculosis, but the specific genes involved have not yet been fully characterized. NRAMP1/SLC11 A1 and P2X(7) genes have been linked to increased risk for tuberculosis in some African and Asiatic populations. To explore the potential role of these genes in the susceptibility to pulmonary tuberculosis in a Mexican mestizo population, we evaluated the association of D543N and 3'-UTR polymorphisms in NRAMP1/SLC11 A1 and - 762 and A1513C polymorphisms in P2X(7) genes with the risk for tuberculosis. Polymerase chain reaction (PCR) amplification of genomic DNA followed by restriction fragment length polymorphism analysis, and allelic-specific PCR was employed. We found no significant differences in allelic frequency in NRAMP1/SLC11 A1 gene polymorphisms in 94 patients with tuberculosis compared to 100 healthy contacts. Similarly, no significant association of the P2X(7)-762 gene polymorphism with tuberculosis was detected. In contrast, the P2X(7) A1513C polymorphism was associated significantly with tuberculosis (P = 0.02, odds ratio = 5.28, 95% CI, 0.99-37.69), an association that had not been reported previously. However, when the function of P2X(7) was assessed by an L-selectin loss assay, we did not find significant differences in patients compared to healthy contacts or between PPD(+) and PPD(-) control individuals. This study further supports the complex role of P2X(7) gene in host regulation of Mycobacterium tuberculosis infection, and demonstrates that different associations of gene polymorphisms and tuberculosis are found in distinct racial populations.

Association of HLA-DRB1*16 with chronic discoid lupus erythematosus in Mexican mestizo patients

BACKGROUND

Chronic discoid lupus erythematosus (CDLE) is present in 15-30% of patients with systemic lupus erythematosus (SLE). Approximately 5% of CDLE cases can evolve to SLE at some stage of the disease.

AIM

The aim of this study was to determine gene frequencies of HLA-DRB1 alleles in Mexican mestizo patients with CDLE, irrespective of the presence of systemic disease.

METHODS

The study comprised 28 Mexican mestizo patients with CDLE who were attending the Passover Dermatology Centre, in Mexico City. HLA-DRB1 and DQ allele typing was performed by sequence-specific oligotyping after DNA amplification using PCR. The study also included 99 ethnically matched healthy individuals as controls.

RESULTS

In the patient group, a significantly increased gene frequency was found for the HLA-DR4 (P = 0.016, OR = 2.24, 95% CI 1.14-4.38) and HLA-DR16 alleles (P = 0.005, OR = 5.51, 95% CI 1.49-21.08).

CONCLUSION

HLA-DRB1 alleles seem to be involved in the genetic susceptibility to CDLE in the Mexican mestizo population.

HLA-E polymorphism in Amerindians from Mexico (Mazatecans), Colombia (Wayu) and Chile (Mapuches): evolution of MHC-E gene

Human leukocyte antigen (HLA)-E is a nonclassical class I (Ib) gene with a restricted polymorphism. Only eight DNA alleles and three proteins of this gene have been described and their frequencies analyzed in Caucasian, Oriental, Asian Indian, and Negroid populations. In the present study, HLA-E polymorphism has been analyzed in six Amerindian and Mestizo populations from North and South America and compared with previously described populations. HLA-E*0101 is the most frequent allele found in all populations except in Afrocolombian and Wayu Amerindians, in which blood group analyses show a high admixture with Caucasian and African populations. Mazatecan and Mapuche (two Amerindian groups from North and South America, respectively) presented similar HLA-E frequencies, whereas Wayu Indians are more similar to the Afrocolombian population. The Mexican and Colombian Mestizo show similar allele frequencies to Amerindians with high frequencies of HLA-E*0101 and HLA-E*010302 alleles. Also, frequencies in Negroids and Asian Indians present a similar distribution of HLA-E alleles. These data are in agreement with worldwide restricted polymorphism of HLA-E because no new allele was detected in the six populations studied. The allelic frequencies show differences among Caucasian, Oriental, Mestizo and Indian populations. Ape major histocompatibility complex-E allelism is also very restricted: common chimpanzee (one allele); bonobo (two alleles); gorilla (two alleles); orangutan (one allele); rhesus monkey (eight alleles); cynomolgus monkey (two alleles); and green monkey (two alleles).

Prevalence of HLA Antibodies and Its Impact on Graft Function in a Group of Kidney Transplant Recipients: A Cross-Sectional Study

HLA alloantibodies (Abs) are associated with chronic rejection and poorer graft survival. The current study was designed to document the prevalence of HLA Abs in a group of kidney transplant recipients (KTR) and its impact on graft function.

PATIENTS AND METHODS

283 KTR transplanted between January 1990 and December 2003 who had a functional graft were invited to participate. 198 KTR were enrolled. HLA class I and II Abs were measured by Luminex-One Lambda. Graft function was assessed by DeltaCr and GFR calculated by the Levey formula.

RESULTS

Median post-kidney transplant (post-KT) follow-up was 51.4 (4.3 to 176.3) months. Forty-four (22.2%) KTR were found to have class I and/or class II Abs. Eleven had both class I and II Abs, ten were positive only for class I, and 23 for class II. Overall, no significant difference was seen in renal function. The DeltaCr for Ab positive and Ab negative were -0.24+/-0.84 and -0.17+/-0.60 mg/dL (P=0.54), respectively. The GFR for Ab positive and Ab negative were 64.4+/-26 and 60.2+/-20 mL/min (P=0.25), respectively. No statistically significant difference was found between HLA Abs and number of HLA mismatches, gender, blood transfusions, pre-KT pregnancies, DGF, history of acute rejection, and chronic allograft nephropathy. Adjusting analysis by transplant year showed no significant difference.

CONCLUSION

The prevalence of HLA antibodies was similar to previous reports. In this cross-sectional study, the presence of HLA antibodies was not related to a negative impact on renal function.

Allele frequencies for 15 autosomal STR loci and admixture estimates in Puerto Rican Americans

Allelic frequencies of 15 short tandem repeats (STR) markers (CSF1PO, FGA, THO1, TPOX, VWA, D3S11358, D5S818, D7S820, D8S1179, D13S317, D16S539, D18S51, D21S11, D19S433 and D2S1338) were determined using the AmpFl STR Identifiler PCR Amplification Kit in Puerto Rican American individuals (N=205) from Massachusetts. The FGA, D18S51 and D2S1338 loci had a high power of discrimination (PD) with values of 0.967, 0.965 and 0.961, respectively. Significant deviations from the Hardy-Weinberg (HW) equilibrium were not detected. An important genetic contribution of Caucasian European (76.4%) was detected in Puerto Rican Americans. However, comparative analysis between Puerto Rican American and other neighboring populations from United States mainly with African and Caucasian Americans, revealed significant differences in the distribution of STR markers. Our results are important for future comparative genetic studies of different American ethnic groups, in particular a cultural group called Hispanic-Americans and should be helpful for forensic and paternity testing.

HLA antigens and juvenile onset spondyloarthritides: negative association with non-B27 alleles

OBJECTIVE

To describe the association between HLA-B and HLA-DR genes and juvenile onset spondyloarthritides (SpA) in Mexicans.

METHODS

The study included 66 consecutive patients with SpA (45 with ankylosing spondylitis (AS) and 21 with undifferentiated SpA) and 99 non-related healthy controls. The HLA-A, -B and DR alleles were detected by the polymerase chain reaction with the sequence-specific primers technique. Statistical methods included the Mantel-Haenzel chi2 test, Fisher's exact test, and Woolf method for odds ratio (OR).

RESULTS

The frequency of HLA-B27 was significantly increased in the whole group (pC < 10(-3), OR = 53.0, aetiological fraction = 51%), particularly in AS (pC < 10(-3), OR = 67.42, aetiological fraction 57%). In contrast, the frequencies of HLA-B44, and HLA-B14 were significantly decreased. Also, a weak negative association HLA-DR5 (p < 0.05) was found.

CONCLUSION

Apart from an expected significant association between HLA-B27 and juvenile-onset SpA, particularly AS, we found negative associations with HLA-B44, B14, and DR5. There was also a trend for HLA-B15 and DR1 associations with SpA.

HLA-DRB1 alleles encoding the “shared epitope” are associated with susceptibility to developing rheumatoid arthritis whereas HLA-DRB1 alleles encoding an aspartic acid at position 70 of the β-chain are protective in Mexican mestizos

The risk to develop rheumatoid arthritis (RA) has been associated with the presence of HLA-DRB1 alleles encoding the "shared epitope" (SE). Additionally, HLA-DRB1 alleles encoding an aspartic acid at position 70 (D70+ ) have been associated with protection against the development of RA. In this study we tested the association between either SE or D70+ and rheumatoid arthritis in Mexican Mestizos. We included 84 unrelated Mexican Mestizos patients with RA and 99 unrelated healthy controls. The HLA-typing was performed by PCR-SSO and PCR-SSP. We used the chi-squared test to detect differences in proportions of individuals carrying at least one SE or D70+ between patients and controls. We found that the proportion of individuals carrying at least one HLA-DRB1 allele encoding the SE was significantly increased in RA cases as compared to controls (p(c) = 0.0004, OR = 4.1, 95% CI = 2.2-7.7). The most frequently occurring allele was HLA-DRB1*0404 (0.161 vs 0.045). Moreover, we observed a significantly increased proportion of HLA-DRB1 SE+ cases with RF titers above the median (p = 0.005). Conversely, the proportion of individuals carrying at least one HLA-DRB1 allele encoding the D70+ was significantly decreased (p(c) = 0.004, OR = 0.4, 95% CI 0.2-0.7) among RA patients compared with controls. In conclusion, the SE is associated with RA in Mexican Mestizos as well as with the highest titers of RF.

HLA class II genotypes in Mexican Mestizo patients with myasthenia gravis

Myasthenia gravis is an autoimmune, heterogeneous disorder, characterized by the presence of antibodies against acetylcholine receptors at the neuromuscular junction. There is a strong evidence that an individual's genetic composition is an important predisposing factor for the development of the disease. To correlate HLA class II genotypes with thymic pathology in Mexican Mestizo patients who had been subjected to thymectomy. HLA class II genes were analyzed in 60 patients and in 99 healthy ethnically matched controls. Thymic hyperplasia, atrophy, thymoma, and normal histology were encountered in 56, 33, 8 and 2% of patients, respectively. HLA-DR11 was significantly increased in patients with thymoma compared with healthy controls (pC = 0.001, OR = 13.35, 95% CI 3.5-51.3), compared with the subgroup of hyperplasia patients (pC = 0.005, OR = 15.5, 95% CI 2.78-95.58) and with the atrophy subgroup (pC = 0.04, OR = 10.5, 95% CI 1.75-70.95). This study provides the evidence of an association between HLA class II alleles with clinical and genetic heterogeneity in myasthenia gravis, particularly in those with thymoma (HLA-DR11).

Acute myocardial infarction with cardiogenic shock: treatment with mechanical circulatory assistance and heart transplantation

The mortality of cardiogenic shock (CS) after an acute myocardial infarction (AMI) still remains high. Thrombolysis, PTCA or CABG, when possible, can improve the results, but when all the treatments fail death is almost certain.

OBJECTIVE

We investigate the use of the mechanical circulatory assistance (MCA) and heart transplantation (HT) to improve the adverse results in this irreversible situation.

METHODS

Among 11 patients with irreversible CS after an AMI we used a MCA (Abiomed BVS-5000). After improvement and hemodynamic stabilization, we performed heart transplantation in 7 patients of mean age 52 years (35-60) including two women. The MCA was univentricular in 7 patients and biventricular in 4. Mean duration of the MCA was 5 days (1-12).

RESULTS

Three patients died during the MCA: two due to cerebrovascular accidents and one multiorgan failure. Weaning was possible in one patient. Among Seven transplanted patients one died due to sepsis. Seven (64%) patients are long-term survivors.

CONCLUSION

When all the treatments have failed for CS after an AMI, MCA may be used as a bridge to heart transplantation in a select group of patients where the procedure is not contraindicated. The long-term results of 64% survivors in our experience is satisfactory.

Biological relevance of the polymorphism in the CCR5 gene in refractory and non-refractory rheumatoid arthritis in Mexicans

OBJECTIVE

The aim of this study was to analyze the frequencies of the CCR5 delta 32 deletion and HLA class II alleles in Mexican Amerindian populations and its relevance in the development and severity of RA.

METHODS

We studied 212 Mexican Mestizo subjects (40 patients with refractory RA, 102 patients with non-refractory RA and 70 healthy individuals). At the same time, to evaluate the ethnicity of the CCR5 delta 32 deletion we also studied 192 individuals from three Mexican Amerindian populations (70 Mayo (Capomo) individuals, 61 Teenek individuals, and 61 Mazatecan Indians). The delta 32 deletion in the CCR5 structural gene and HLA-DRB1 were determined by a PCR-SSP and a PCR-SSO procedure, respectively.

RESULTS

In the non-refractory RA group the CCR5 delta 32 gene frequency was 0.019 and the following genotype frequencies were observed: CCR5/CCR5 = 98.0%, CCR5/CCR5 delta 32 = 1.9% and CCR5 delta 32/CCR5 delta = 1.0%. In the refractory RA group the CCR5 delta 32 gene frequency was 0.025 and the genotype distribution was similar to that in the non-refractory RA group. The deletion was not detected in the Mexican Mestizo healthy group, or among the Teenek and Mayo Amerindians, all being individuals homozygous for the wild type allele. In the Mazatecan group the deletion frequency was 1.6% (g.f. = 0.016). We observed a significant increase in the frequency of the DRB1*07 allele in severe RA patients in relation to the non-severe RA group (p = 0.02, OR = 5.65, 95% CI = 0.95-43.05).

CONCLUSION

Our results suggest that the CCR5 delta 32 deletion is not common in Mexican Amerindian populations and this study does not support an important role of CCR5 delta 32 in the pathogenesis of RA or a severe form of the disease in Mexicans.

IgG antibodies to enterobacteria 60 kDa heat shock proteins in the sera of HLA-B27 positive ankylosing spondylitis patients

OBJECTIVE

To study the association of HLA-B27 and the IgG response to the 60 kDa HSPs of Klebsiella pneumoniae, Yersinia enterocolitica, Shigella flexneri, Escherichia coli and Salmonella typhi.

METHODS

IgG against the 60 kDa HSPs of enterobacteria was determined by ELISA in the sera from 49 HLA-B27+ ankylosing spondylitis (AS) patients; 41 HLA-B27+ healthy relatives of AS patients and 101 HLA-B27-unrelated healthy individuals.

RESULTS

HLA-B27+ patients and healthy individuals, showed significantly higher IgG antibody levels to the Klebsiella, Yersinia and Salmonella HSPs than HLA-B27- healthy controls. B27+ patients had a significantly higher response to E. coli HSP than the two other groups. IgG response anti-Shigella HSP was similar in the three groups.

CONCLUSIONS

There is a relationship between HLA-B27 and the response to HSPs 60 from Klebsiella, Yersinia, Escherichia and Salmonella, that may be important in the initiation of AS.

Clinical and immunogenetic characterization of Mexican patients with 'rhupus'

The coexistence of systemic lupus erythematosus and rheumatoid arthritis (rhupus), is a rare clinical condition. To date, 50 cases of rhupus have been described worldwide; however, the lack of clinical criteria for this rheumatic condition has created confusion in the characterization of this disorder. Nevertheless, in this paper we describe a comprehensive clinical and serological characterization of a cohort of 22 Mexican patients with rhupus, supported by generic HLA-DR phenotyping. We found that rhupus patients have a special clinical behavior. In this setting, the signs and symptoms of rheumatoid arthritis prevail, little organic damage associated with systemic lupus erythematosus (SLE) exists and none of the cases present thrombosis or morbidity during pregnancy in spite of presenting a high frequency of anticardiolipin antibodies. We also found an increased frequency of HLA-DR1 and HLA-DR2 alleles compared to healthy ethnically matched controls, systemic lupus erythematosus and rheumatoid arthritis patients.

Surgical treatment of left ventricular free wall rupture after myocardial infarction: case series

AIM

To analyze the results of surgical treatment of left ventricular free wall rupture after acute myocardial infarct in a case series.

METHOD

From 1984 to 2001, 25 patients (10 women and 15 men) were surgically treated in our Center for left ventricular free wall rupture after acute myocardial infarction. Their mean age was 62 years (range, 42-80). Cardiac symptoms (chest pain and/or dyspnea) prior to admission were recorded in 4 patients. One patient had acute myocardial infarction of the anterolateral wall, 6 patients of the lateral wall, 13 patients of the anterior wall, 4 patients of the inferior wall, and one patient had a right ventricle infarction. Thrombolytic therapy was administered in 10 patients, according to the criteria of the American Heart Association and Spanish Society of Cardiology criteria. In all patients, the final diagnosis was established echocardiographically before the surgery.

RESULTS

All patients underwent surgical intervention on an emergency basis. Extracorporeal circulation was used in the first 9 cases, whereas the next 16 patients had off-pump surgery. Two patients had heart arrest during off-pump surgery, which required extracorporeal circulation support. One patient was found false positive for rupture only at surgery. In the first 4 cases, we performed a direct suture after excising necrotic tissue, in the next 15 cases we sutured a patch over the infarction zone, and in the last 5 patients we used Teflon patch fixed with fibrin glue and polypropylene and stitched to the epicardium with a continuous suture. Out of 24 patients, 8 died: one in the surgical room from uncontrollable bleeding and another 7 between 30 and 90 days after the surgery in the intensive care unit. All of them underwent surgery with extracorporeal circulation. There were no deaths among the patients undergoing off-pump surgery. Three out of 4 patients in whom direct suture and necrotic tissue excision was performed died in the hospital. Five out of 19 patients in whom patch correction with direct suture was done died in the hospital.

CONCLUSION

The left ventricle free wall rupture, as a complication of acute myocardial infarction, can be diagnosed early and treated on time. Rapid diagnosis and emergency surgery are crucial for successful treatment of patients with impending heart rupture. Off-pump surgery and patch with glue technique seem to yield best results.

Identification of two homologous antigenic peptides derived from L1 HPV-16 and 18 proteins specific for the HLA-B*3901 allele

In this work we present evidence that the homologous peptides IHSMNSTIL and IHSMNSSIL derived from L1 HPV-16 and 18 proteins respectively, and with high specificity for the allele HLA-B*3901, according with an algorithm prediction program, induced T cell stimulation in patients with advanced cervical cancer positive for HPV-16 or 18 infection and for the HLA-B*3901 allele. Interestingly, T lymphocytes derived from a patient with HPV-18 infection and stimulated with the peptide IHSMNSTIL were capable to kill a cervical cancer cell line named Rova, derived from the tumor of the same patient. In addition, the cytotoxic activity was strongly increased when this cell line was previously treated with hrIFN-gamma. These results suggest that the CTL immune response to L1 HPV-16 and 18 protein derived epitopes is maintained in patients with advanced cervical cancer within specific alleles, and opens the possibility that homologous epitopes may be used in the generation of prophylactic vaccines for cervical tumors bearing different HPV-types.

LMP2 and LMP7 gene polymorphism in Mexican populations: Mestizos and Amerindians

Low molecular weight polypeptide (LMP) genes are located within the major histocompatibility complex and have been associated with autoimmune diseases such as ankylosing spondylitis. In order to define the distribution of LMP genes in Mexican populations, the LMP2 and LMP7 polymorphism was analyzed in 312 Mexican individuals (95 Mexican Mestizos, 48 Nahuas, 56 Mazatecans, 50 Teenek, and 63 Mayos) belonging to different ethnic groups. In Mexican populations both Mestizos and Amerindians presented similar distribution of LMP2 and LMP7 polymorphisms, except Nahuas and Mayos who presented the higher frequencies of LMP2-H/H and the lowest frequencies of LMP2-H/R genotypes (P < 0.05 when compared with Mexican Mestizos). The LMP7-K/K genotype was absent in Nahuas, Teenek and Mayos and only one Mazatecan individual presented this genotype. Differences with other populations were found in Mexicans. An increased frequency of LMP2-H and a decreased frequency of LMP2-R alleles were observed in Mexican Amerindians (Nahuas and Mayos) when compared with Brazilian Amerindians (Kaingang and Guarani) and Caucasians (Spaniards) (P < 0.05). All Mexican populations (Mestizos and Amerindians) presented an increased frequency of LMP7-Q allele and a decreased frequency of LMP7-K allele when compared to Brazilian Amerindians (Kaingang), Caucasians (United States) and Asian (Japan) populations (P < 0.05). Genetic distances showed that Mexican Mestizos have an important relation with Spaniards and with all Mexican Amerindians. The present data corroborate the influence of Spaniard and Amerindian genes in the Mexican Mestizo population and could help to define the true significance of LMP polymorphism as genetic and evolutive marker in the Amerindian populations.