The HLA system in the prevalent Mexican Indian group: the Nahuas

MHC Class II haplotypes of Colombian Amerindian tribes

We analyzed 1041 individuals belonging to 17 Amerindian tribes of Colombia, Chimila, Bari and Tunebo (Chibcha linguistic family), Embera, Waunana (Choco linguistic family), Puinave and Nukak (Maku-Puinave linguistic families), Cubeo, Guanano, Tucano, Desano and Piratapuyo (Tukano linguistic family), Guahibo and Guayabero (Guayabero Linguistic Family), Curripaco and Piapoco (Arawak linguistic family) and Yucpa (Karib linguistic family). for MHC class II haplotypes (HLA-DRB1, DQA1, DQB1). Approximately 90% of the MHC class II haplotypes found among these tribes are haplotypes frequently encountered in other Amerindian tribes. Nonetheless, striking differences were observed among Chibcha and non-Chibcha speaking tribes. The DRB1*04:04, DRB1*04:11, DRB1*09:01 carrying haplotypes were frequently found among non-Chibcha speaking tribes, while the DRB1*04:07 haplotype showed significant frequencies among Chibcha speaking tribes, and only marginal frequencies among non-Chibcha speaking tribes. Our results suggest that the differences in MHC class II haplotype frequency found among Chibcha and non-Chibcha speaking tribes could be due to genetic differentiation in Mesoamerica of the ancestral Amerindian population into Chibcha and non-Chibcha speaking populations before they entered into South America.

The epidemiology of multiple sclerosis in Latin America and the Caribbean: a systematic review

The incidence and prevalence of multiple sclerosis (MS) varies geographically as shown through extensive epidemiological studies performed mainly in developed countries. Nonetheless, scant data is available in Latin America and the Caribbean (LAC). The objective of this review is to assess epidemiological data of MS in LAC. We conducted a systematic review of published articles and gray literature from January 1995 to May 2011. Twenty-two studies met the inclusion criteria after full-text review. Incidence data were found in only three studies and ranged from 0.3 to 1.9 annual cases per 100,000 person-years. Prevalence was reported in 10 studies and ranged from 0.83 to 21.5 cases per 100,000 inhabitants. The most prevalent subtype of MS was the relapsing–remitting form (48% to 91% of the series). No data about mortality were found. This study showed low frequency for MS in LAC compared with North American and European countries. The role of environmental and genetic factors should be well studied, providing new insights about its etiology.

Multiple sclerosis in Caucasians and Latino Americans

Epidemiological and genetic studies suggest that the prevalence, median age of onset, and specific phenotypes of multiple sclerosis (MS) are different in Caucasians and Latino Americans. Recent epidemiological studies indicate an increase in MS prevalence in Latin America (LA), where the south-north gradient of latitude described for Nordic countries does not exist. Analysis of MS epidemiological and specific aspects in LA suggests that susceptibility and clinical behavior of the disease are related to mixtures and admixtures of genes in the population. MS is not present in Amerindians with Mongoloid genes, such as occurs in other pure ethnic groups. Surely, future studies will be carried out to obtain more reliable information. In this review, we contrast and analyze the available data of MS in LA and endemic countries.

High-resolution molecular characterization of the HLA class I and class II in the Tarahumara Amerindian population

We describe for the first time the high-resolution profiling of HLA-A, -B, -C, -DRB1, -DQB1 and -DPB1 in a culturally and geographically distinct Mexican ethnic group, the Tarahumaras. The alleles most frequently found by reference strand-mediated conformational analysis in this population were for class I: HLA-A*240201, *020101/09, *0206, *310102, *680102; HLA-B*4002, *1501, *510201, *3501/02/03, *4005, *4801; HLA-Cw*0304, *0801, *0102, *040101; and for class II: HLA-DRB1*080201, *1402, *040701; HLA-DQB1*0402, *0301, *0302/07; HLA-DPB1*0402, *0401, *020102. In addition, a novel allele, HLA-A*0257, was found. Based on comparison of presently known HLA-DRB1 and -DQB1 allele frequencies in Amerindian groups and worldwide populations, the Tarahumaras are unexpectedly more related to the geographically and linguistically distant Aymara and Terena Amerindian groups than they are to neighbouring tribes.

Genetic relationship of the Guambino, Paez, and Ingano Amerindians of southwest Colombia using major histocompatibility complex class II haplotypes and blood groups

We analyzed the Amerindian tribes, Guambiano, Ingano, and Paez of the southwest section of Colombia by major histocompatibility complex class II typing and blood group analysis in order to establish their genetic relationship. In addition, genetic admixture with Caucasian and African ancestry were determined based on blood group typing. The Paez showed admixture with Caucasian populations (22.4%), while the Ingano and Guambiano showed some admixture with Black populations (9.2 and 4.6%, respectively). The Ingano had MHC class II haplotypes found mainly in Amerindian and Asian populations with no evidence of class II haplotypes of African origin. MHC class II haplotypes of Amerindian and Asian populations and some haplotypes frequently found in European Caucasians and Asians and haplotypes of European Caucasians were found in Guambiano and Paez tribes. We compared our results with those previously reported for four Amerindian tribes on Northern Colombia. The presence of some MHC class II haplotypes in the Guambiano, Paez, and Ingano tribes and their absence in the Chibcha speaking groups of Northern Colombia suggest that these tribes originated, together with other Amerindians, from a separate migration or by genetic drift from an ancestral population. Therefore they are genetically distant from Chibcha speaking tribes of Colombia.

Contribution of HLA class II genes to end stage renal disease in mexican patients with type 2 diabetes mellitus

To analyze the contribution of MHC class II genes in type 2 diabetes mellitus (DM) with end stage renal disease (ESRD), we examined the distribution of HLA-DRB1, DQA1, DQB1 loci in Mexican Mestizos of Central Mexico, using PCR-SSOP and PCR-SSP. Three groups were included: 47 type 2 diabetic ESRD patients; 42 patients with ESRD and 50 type 2 DM patients with no kidney complication. The results were compared with those of 101 controls of the same area. The median since DM was first diagnosed, was 18 years prior to the onset of ESRD. The frequencies of DRB1*1502 and DQB1*0501 were increased in DM patients with ESRD (p = 0.004; RR = 7.4, CI = 1.5-37; EF = 0. 13; p = 0.007; RR = 2.9, CI = 2.3-3.5, EF = 0.21, respectively). In contrast, DRB1*0407 was decreased in the same group (p = 0.0008, RR = 0.2; CI = 0.035-0.70, PF = 0.19). Diabetic patients with DRB1*1502 are 8.8 times more likely to develop ESRD, independently of the duration time of DM. DRB1*1502 contributes to the susceptibility to ESRD while DRB1*0407 is involved in protection. The residue at DRB1-74 differs in these alleles: DRB1*0407 has glutamic acid and DRB1*1502 has an alanine, suggesting that this substitution may be important for both, peptide anchoring and for presentation to the T cells.

Molecular analysis of HLA class I alleles in the Mexican Seri Indians: implications for their origin

The molecular analysis of HLA class I loci has demonstrated that, although, the genetic profile is restricted in Amerindians, several micropolymorphisms may be important in conferring a biological advantage. We analyzed the HLA-A and B genetic profile of Seris, a Mexican Indian tribe living in northwestern Mexico in the state of Sonora. There are presently only 619 individuals. Our study included 100 Seris belonging to nine families. HLA-A and -B loci typing was performed by polymerase chain reaction using an amplification refractory mutation system (PCR-ARMS) on a select group of samples; all of them were typed by polymerase chain reaction using sequence-specific oliogonuoleotide probes (PCR-SSOP) at a low-intermediate resolution level. The correlation between the techniques was 100%. Only five HLA-A alleles and seven HLA-B alleles were found. A*0201, A*68, A*31, A*24, B*3501, B*40, B*51, B*3512 and B*15 were present in over 5% of the individuals. B*27052 was detected in 2%. B27 is absent in any other Mexican Indian groups previously studied. The presence of B27 may be the result of a founder effect due to different waves of southward migrations. The B-locus is more diverse and the prevalent haplotypes were: A*0201-B*3501, A*0201-B*40, A*0201-B*3512, A*31-B*51, A*68-B*3501 and A*68-B*40. This genetic profile is different from the pattern of other Mexicans. The phylogenetic tree suggests that Seris are more closely related to the Warao Indians from Venezuela, who live in a similar ecosystem, and to some groups of Argentina, than they are to the Mexican Lacandones who live in the jungle. These data emphasize the relevance of the interaction between genes and environment.

HLA-DR is strongly associated with Vogt-Koyanagi-Harada disease in Mexican Mestizo patients

PURPOSE

To analyze the genetic background of human leukocyte antigens (HLA) of Vogt-Koyanagi-Harada (VKH) disease in Mexican Mestizo patients in order to establish whether the pathogenesis is related to the same genes or sequences described in other populations.

PATIENTS AND METHODS

In 48 VKH patients, we performed HLA class I and class II typing using the standard microlymphocytotoxicity tests; a group of 100 nonrelated healthy subjects were analyzed for comparison. Antigen and gene frequencies were calculated for every antigen tested in patients and in controls.

RESULTS

The frequency of HLA-DR4 was significantly increased in VKH Mexican patients (x2Y = 19.95; p = 0.00001; pc = 0.0002; RR = 5.3; EF = 0.52); a discrete increase in DR1 was also found (p = 0.02). HLA-DQ8 also showed a significant association with the disease with a lower RR (3.2) and EF (0.41) than DR4.

CONCLUSION

The strong association found with HLA-DR4 and the slight DR1 increase shown in Mexican patients with VKH suggest that a common shared sequence present in the third hypervariable region of DRB1 genes is relevant for the expression of the disease. The stronger association with DR4 than the one with DQ8 suggests that the DR locus carries the primary susceptibility genes involved in the pathogenesis of VKH.

Polymorphism of the HLA-DRB1 locus in Colombian, Ecuadorian, and Chilean Amerinds

We have characterized the DRB1 genotypes in a sample of 64 South American Indians drawn from populations in Chile, Colombia, and Ecuador. No novel DRB1 alleles were found in the total of 17 different alleles characterized, indicating that rapid allelic generation does not occur at the DRB1 loci, in contrast to HLA-B. Comparison between Chilean and Colombian/Ecuadorian samples revealed no major differences in their allelic frequencies. In the combined Amerind sample the HLA-DRB1*0407 and HLA-DRB1*1402 alleles occurred in the highest frequencies (38% and 22%, respectively). Genetic distance measurement showed the HLA-DRB1 frequencies reported here to agree with findings in other Amerind groups. The high frequencies of both HLA-DRB1*0407 and HLA-DRB1*1602 alleles, in conjunction with their absence in Siberian samples, suggest that migratory groups other than Siberians may have been involved in the peopling of the Americas.

Description of a novel HLA-B35 (B*3514) allele found in a Mexican family of Nahua Aztec descent

A new allele, HLA-B*3514, has been found in a Mexican family from Nahua descent. Its exon 2 is identical to that of B*3501 allele, but exon 3 bears a 3-base difference at codons 152 and 156, which results in Val-->Glu and Leu-->Trp changes, respectively, in the corresponding HLA molecule at the peptide-binding site. These substitutions may have originated from a DNA stretch donation from an allele belonging to the B15 group, enabling HLA-B*3514 to cope with the presentation of a new set of antigenic peptides. The high frequency of serologic B35 in Amerindians, together with the variety of B35 alleles detected by DNA sequencing in these populations, suggest that a frequent B35 subtype was present in the founder population and that several B35 subtypes may have been recently generated, probably due to the abrupt arrival of new pathogens following European invasions.

Is the frequency of multiple sclerosis increasing in Mexico?

Multiple sclerosis has steadily increased in Mexican mestizos from an apparently rare disorder in the 1970s to the second most frequent cause of admission to a neurology ward in the 1990s. Most patients belonged to high socioeconomic and educational groups. Familial incidence was low. Age at onset was younger than in other series and long term disability was milder than in patients from countries in which the disease is apparently more prevalent.

Allelic heterogeneity of HLA-B35 subtypes in different populations as assessed by DNA typing

HLA-B35, a class I antigen differentially associated to several diseases in different ethnic groups, comprises at least eight alleles which differ among them by one to six amino acids. In the present work a rapid DNA typing procedure was used to investigate the distribution of the various HLA-B35 alleles in different populations. The approach is based on a group-specific PCR amplification of a set of closely related HLA-B alleles sharing a Thr in position 45 of the alpha-1 domain. The amplified DNA was then hybridized to a panel of sequence-specific oligonucleotide (SSO) probes designed to recognize the polymorphic residues in previously reported HLA-B35 subtypes. This methodology was successfully tested in 100 individuals of four different populations, previously typed by serology as HLA-B35, and in six reference panel cells of the 10th International Histocompatibility Workshop. HLA-B*3501 was the predominant subtype in all populations. B*3502, B*3503 and, to a lesser extent B*3508, were also found. Among Mexican Mestizos, thirteen individuals had patterns of SSO hybridization suggestive of new B35 alleles. The evolutionary considerations on the different B35 alleles and their extended B35,Cw4 haplotypes are discussed.

Major histocompatibility complex class II alleles and haplotypes and blood groups of four Amerindian tribes of northern Colombia

MHC class II alleles and haplotypes were determined from unrelated individuals and families of the Arhuaco (n = 107), Kogi (n = 42), Arsario (n = 18), and Wayú (n = 88) tribes located in the northern part of Colombia. Class II DRB, DQA1, and DQB1 alleles were determined by PCR-SSO and PCR-RFLP based methods. Four haplotypes, [DRB1*0407, DRB4*0101, DQA1*03, DQB1*0302]; [DRB1*0403, DRB4*0101, DQA1*03, DQB1*0302]; [DRB1*1402/1406, DRB3*0101, DQA1*0501, DQB1*0301]; and [DRB1*0802, DQA1*0401, DQB1*0402], were observed among these four tribes. In addition to these haplotypes, the Wayú Indians showed a frequency of 21.3% for the [DRB1*1602, DRB5*02, DQA1*0501, DQB1*0301] haplotype, 13.1% for the [DRB1*0411, DRB4*0101, DQA1*03, DQB1*0302] haplotype, and 8.1% for the [DRB1*0411, DRB4*0101, DQA1*03, DQB1*0402] haplotype. Red cell antigen typing was used to calculate genetic admixture. The Kogi and Arsario showed no genetic admixture while the Arhuaco tribe showed admixture with genes of African origin and the Wayú showed admixture with Caucasians as well as genes of African origin. These findings were confirmed by the MHC class II allele and haplotype data obtained, as alleles and haplotypes of Caucasian and African origin were detected in the Wayú and Arhuaco and not in the Kogi or Arsario. These studies will be important in disease association and transplantation studies for Amerindian and colombian populations and for correlating genetic traits with the anthropologic and linguistic data available in order to better understand the Amerindian populations.

The HLA polymorphism of two distinctive South-American Indian tribes: the Kaingang and the Guarani

The HLA-A, B, C, DR and DQ antigens of 240 Kaingang and 98 Guarani individuals have been characterized. The most frequent antigens found among the Kaingang are A31, 2, 24; B35, 51, 39, 48; Cw4, 7, 3, 1; DR8, 4, 2; DQ blank, 3. In the Guarani, they are A2, 28, 31; B40, 62, "53G"; Cw3, 4; DR2, 4, 8, 6; DQ3, blank. B " 53G" is an unusual antigen of the B5 cross-reactive group. DQ blank possibly corresponds to DQ4, not tested in this study. The reaction patterns of B35, B40 and DR4 indicate intra-tribal (of B35 and B40), and inter-tribal (DR4, B40 and B35) heterogeneity of these antigens. 408 Kaingang and 141 Guarani haplotypes were defined by segregation analysis. Of the commonest 10 Guarani and 9 Kaingang haplotypes, only one is shared by both tribes. Significant, positive linkage disequilibrium values for HLA-A,B; HLA-A,C; HLA-B,DR and most HLA-B,C antigen pairs were also different for the two populations. Genetic distance estimates between these two and another seven South-American Indian populations, and relative to the major human races (negroids, caucasoids, and mongoloids) reveal a comparatively high degree of divergence between the Kaingang and the Guarani, which is uncommon for Amerindian populations living close one to another.

HLA polymorphism in a Mataco South American Indian tribe: serology of class I and II antigens. Molecular analysis of class II polymorphic variants

In the present study, HLA-A, B, C, DR, DQ, and DP loci were analyzed in a group of Mataco Amerindians of Argentina. Using reagents from the 11th International Histocompatibility Workshop (11th IHW), class I specifities such as Bw70, Bw75, and Bw48 were found in this population, other than the HLA determinants commonly described in South American Indians. The class II antigens found were DR4, DRw14, and DRw8 at the DR locus, and DQw4 and DQw7 at the DQ locus. The analysis of DRB1-DR4 related alleles, performed by PCR amplification and oligonucleotide probe hybridization, showed the presence of DRB1*0403, *0404, *0405, and *0411 in individuals from this ethnic group. By the analysis of DRB1-DRw14 related alleles, two variants were found: DRB1*1402 and DRB1*1406, the latter provisionally called DRB1 14.6 in 11th IHW. The DRw8-related allele present was DRB1*0802. The analysis of DRB3 gene revealed only the presence of DRB3*0101 allele in DRw14 individuals. DPB1 locus was also analyzed in unrelated individuals of the same population. Only five DPB1 alleles were found: DPB1*0201, *0301, *0402, *0501, and *1301 over the 19 previously described in the literature. These findings emphasize the restricted HLA class I and II variation observed in this ethnic group as it has been previously shown in other American groups. Some particular haplotypes in this Mataco tribe are described in this work.

HLA alleles in the population of Cartagena (Colombia)

It is known from historical records that the population of Cartagena (Colombia) is a mixture of caucasoids (Spaniards) and negroids (Africans) that is named mulattos. The present study was carried out to determine the distribution of HLA antigens in this population. A sample of 370 individuals was HLA serologically typed; 91 of them were typed for Complement alleles and 47 were DNA typed using PCR amplification and oligonucleotide probes for the HLA-DQA1 locus. The analysis of the allele and haplotype frequencies obtained, together with the genetic distances calculated with other populations, showed that most of the HLA genes of mulattos are from negroids and caucasoids. The Asian and Amerindian contribution is small, consistent with the historical and socioanthropological documentation. For example, A23, Aw34, Aw36 and Bw45, as well as DQA1*0101, DQA1*0301 and BfF have frequencies similar to that observed in negroids. In contrast, many significant differences were observed when comparing the antigen and allele frequencies of mulattos with that of Asians and Amerindians. Our results add evidence to the notion that the arrival of Spaniards in America 500 years ago established several racial mixtures. The HLA characterization of one of these, mulattos, will allow a better application of the HLA technology in the fields of basic research, organ transplantation and forensic medicine among this population.

Unique HLA-DR/DQ associations revealed by family studies in Warao Amerindians. Haplotype and homozygosity frequencies

HLA-A, Cw, B and A, Cw, B, DR genotypes have been assigned, respectively, to 318 and 175 Warao Amerindians belonging to 73 sibships, who were tested with International Histocompatibility Workshop reagents. Only 33% of the theoretically possible three-loci and 7% of the possible four-loci haplotypes were found, with 10 and 6 of them accounting, respectively, for 75% of the total observed. This limited haplotype variability, expected in an inbred population, was not accompanied by either an increased or a decreased frequency of homozygous individuals, as demonstrated by population and family analysis. Inheritance of five HLA loci haplotypes in 20 families showed the expected distribution of parental haplotypes in sibling pairs. The study revealed DR2sh (DRw16), DR4 and DRw6 in association with DQw7, and DRw8 with DQw4, and significant positive linkage disequilibria between Bw62 CW1, B51 DRw16, B39 DR4, Bw62 DRw6, and DRw8 DQw4. The DR2-DQw7 and DRw6-DQw7 associations and the first three paired loci disequilibria mentioned are described for the first time in Amerindians and have not yet been found among Japanese, Negroid, or Caucasoid populations.

Immunogenetic profile of multiple sclerosis in Mexicans

This is the first study on genetic markers in Mexican Mestizos with multiple sclerosis (MS). Patients were born in Mexico, had no family history of MS are middle-class, and have a high-level education. HLA class I, class II determinants, C2, C4, BF, GLO-1, ABO, and Rb red cell systems were analyzed and compared with results of 295 controls. Measles antibodies, glucose, IgG, total proteins, and cell count were measured in cerebrospinal fluid; anti-neuron, T-cell, and B-cell antibodies were determined in serum. MS in Mexican Mestizos was clinically similar to MS reported in high prevalence countries. DRw6, as previously found in Japanese patients, and its subtype, DRw13, were increased in patients in our study (pc = 0.0007, pc = 0.01, respectively), and the combination A3, B7, DR2, was also elevated (pc = 0.003). The polygenicity of the disease is emphasized by the excess of AB group carriers (pc = 0.01). IgG levels were high in patients with DR2 or DRw6 and 67% of the latter had anti-T cell antibodies. Severity of the disease was also related to the DR markers. It is suggested that at least two HLA-DR linked genes and the industrialized environment are important for the expression of MS in Mestizos.