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J Martinez-Laso

Publications and source records attributed to J Martinez-Laso.

At least 19 recordsLinked to original sources
PubMed2005

Origin of Aymaras from Bolivia and their relationship with other Amerindians according to HLA genes.

Aymara Amerindians from the Titicaca Lake Andean highlands are studied for HLA-A, HLA-B, HLA-DRB1 and HLA-DQB1 gene frequencies. Genetic distances, neighbour-joining and correspondence analyses are performed by using other Amerindian and worldwide populations (15384 chromosomes are studied). The HLA genetic profile of Aymaras is different from neighbouring and language-related Quechuas (Incas). Both Quechuas and Aymaras seem to present an HLA-DRB1*0901 high frequency, which is present in a very low frequency or absent in Mesoamericans (Mazatecans, Mayans) and most studied Amerindians. Moreover, it is observed a closer relatedness of Aymaras with Amerindians from the Amazon Basin and Chaco lowlands, compared to Quechuans.

American Indian or Alaska Native↗
PubMed2005

MHC-F DNA sequences in bonobo, gorilla and orangutan.

The major histocompatibility complex (MHC)-F class Ib locus shows a limited polymorphism, and the function of its mainly intracellular protein is not clear. We have identified human leucocyte antigen (HLA)-F orthologous DNA sequences in Pongidae in order to study the MHC-F gene evolution and its products' function. HLA-F orthologous cDNA transcripts are found in chimpanzee and in the new primate species studied (bonobo, gorilla and orangutan). Analyses of the predicted amino acid sequences and their comparison with other primate MHC-F proteins show that MHC-F may be a protein with a typical class I structure and that the key residues of the peptide-binding region (PBR) are highly conserved in MHC-F in all studied primates species. Thus, MHC-F conservation along the primate evolution suggests an important role in cellular physiology. It is possible that the MHC-F protein could be involved, together with MHC-G and MHC-E, in the natural killer (NK) cell activity regulation, although rhesus macaque does not express MHC-G and MHC-E orthologues. The evolutionary pathway of the six-base-pair deletion at exon 2 existing in some primates is put forward.

Amino Acid Sequence↗
PubMed2003

HLA alleles in isolated populations from North Spain: origin of the Basques and the ancient Iberians.

HLA-A, -B, -DRB1, -DQA1 and -DQB1 alleles have been studied in three relatively isolated populations of northern Spain from Cantabria ( Pas Valleys inhabitants or Pasiegos and Cabuernigos) and from the Basque Country (Arratia Valley inhabitants). These populations have been compared with neighbouring ones and other Mediterraneans by using neighbour-joining dendrograms and plane genetic distances.

Alleles↗
PubMed2002

Population genetic relationships between Mediterranean populations determined by HLA allele distribution and a historic perspective.

HLA genes allele distribution has been studied in Mediterranean and sub-Saharan populations. Their relatedness has been tested by genetic distances, neighbour-joining dendrograms and correspondence analyses. The population genetic relationships have been compared with the history of the classical populations living in the area. A revision of the historic postulates would have to be undertaken, particularly in the cases when genetics and history are overtly discordant. HLA genomics shows that: 1) Greeks share an important part of their genetic pool with sub-Saharan Africans (Ethiopians and west Africans) also supported by Chr 7 Markers. The gene flow from Black Africa to Greece may have occurred in Pharaonic times or when Saharan people emigrated after the present hyperarid conditions were established (5000 years B.C.). 2) Turks (Anatolians) do not significantly differ from other Mediterraneans, indicating that while the Asians Turks carried out an invasion with cultural significance (language), it is not genetically detectable. 3) Kurds and Armenians are genetically very close to Turks and other Middle East populations. 4) There is no HLA genetic trace of the so called Aryan invasion, which has only been defined on doubtful linguistic bases. 5) Iberians, including Basques, are related to north-African Berbers. 6) Present-day Algerian and Moroccan urban and country people show an indistinguishable Berber HLA profile.

Africa South of the Sahara↗
PubMed2001

Class II allele and haplotype frequencies in Mexican systemic lupus erythematosus patients: the relevance of considering homologous chromosomes in determining susceptibility.

The aim of the present study was to determine the relevant major histocompatibility complex (MHC) class II alleles in the genetic susceptibility to systemic lupus erythematosus (SLE) in Mexican Mestizo patients. We examined the gene and haplotype frequencies of the HLA-DRB1, DQA1 and DQB1 alleles by polymerase chain reaction-sequence-specific oligonucleotide probes in 81 Mexican SLE Mestizo patients and 99 ethnically matched controls. We found a significantly increased frequency of the HLA-DRB1*0301 (p(c) = 0.031, odds ratio = 2.63) allele and significantly decreased frequencies of the DRB1*0802 (p(c) = 0.035) and DRB1*1101 (p(c) = 0.037) alleles in the SLE group. Haplotype analysis showed increased frequencies of DRB1*0301-DQA1*0501-DQB1*0201 (p(c) = 0.017, odds ratio = 2.97), and decreased frequency of DRB1*0802-DQA1*0401-DQB1*0402 (p(c) = 0.034) in SLE patients. The most frequently detected haplotypes in SLE patients showed different haplotypic combinations in the homologous chromosome from those found in controls. Thus, the combinations detected in SLE patients were either not detected in the control group or infrequently found. The results suggest that the DRB1*0301 is the principal class II allele associated with the genetic susceptibility to SLE in Mexican patients and that the presence of a specific haplotype of the homologous chromosome in patients with DRB1*0407-DQA1*03-DQB1*0302 and DRB1*1501-DQA1*0102-DQB1*0602 haplotypes could have an additive effect on the susceptibility to the disease. Finally, the low frequency of the DRB1*0301 and DRB1*1501 alleles in the control population suggests that the genetic admixture between Mexican Indians and Caucasian populations was an event that could have increased the risk of Mexicans to develop SLE.

Alleles↗
PubMed2001

The correlation between languages and genes: the Usko-Mediterranean peoples.

The usko-Mediterraneans peoples are defined as ancient and present day populations that have lived in the Mediterranean/Middle-East/Caucasus area and have spoken a Basque related language. The present day existing populations show an HLA genetic relatedness which is more or less close according to geographical distance. The Greek sample is an outlying in all genetic analyses, because Greeks have a significant genetic input from sub-Saharan Ethiopians and Blacks. This probably occurred in Pharaonic times. Present day comparisons between genes and languages show a lack of correlation: Macedonian, Palestinians, Kurds, part of Berbers, Armenians, and Turks belong to the old Mediterranean substratum, but they do not speak a language included in the old Mediterranean Dene-Caucasian group. This is due to an "elite"-imposed culture and language. Other ethnic groups speak an "old Mediterranean language" or "usko-Mediterranean language" modified by Roman Latin (i.e., Spanish, Italians), or by other not fully explained processes (Jews). Therefore, the correlation between genes and languages may exist at a macrogeographical level, but not when more precise microgeographical studies are done, as shown in the present "usko-Mediterranean" peoples model.

Africa South of the Sahara↗
PubMed2001

Genetic variation among the Golla pastoral caste subdivisions of Andhra Pradesh, India, according to the HLA system.

The HLA allele frequency distributions have been characterized for the HLA class I and class II loci of the Golla pastoral caste, from Southeast India, subdivided into the subcastes (Puja, Punugu, Kurava, Pokanati, Karnam, and Doddi). Genetic distances, neighbor-joining, correspondence, and haplotype analyses all indicate that the subcastes exhibit a high haplotype variability and that their genetic substratum may be the result of European-Middle East/Asian admixture with the autochthonous populations. The Karnam subcaste seems to be the one that has undergone a higher degree of admixture, when compared with the other subcastes. The Golla speak an old Indian Dravidian language and should theoretically represent the basic Indian substratum that existed before the postulated "Aryan" invasion.

Adult↗
PubMed2001

HLA molecular markers in Tuvinians: a population with both Oriental and Caucasoid characteristics.

HLA class I and class II alleles have been studied for the first time in the Turkish-speaking Tuvinian population, which lives in Russia, North of Mongolia and close to the Altai mountains. Comparisons have been done with about 11000 chromosomes from other worldwide populations, and extended haplotypes, genetic distances, neighbor joining dendrograms and correspondence analyses have been calculated. Tuvinians show an admixture of Mongoloid and Caucasoid characters, the latter probably coming from the ancient Kyrgyz background or, less feasibly, more recent Russian Caucasoid admixture. However, Siberian population traits are not found and thus Tuvinians are closer to Central Asian populations. Siberians are more related to Na-Dene and Eskimo American Indians; Amerindians (from nowadays Iberian--America) are not related to any other group, including Pacific Islanders, Siberians or other American Indians. The 'more than one wave' model for the peopling of the Americas is supported.

Alleles↗
PubMed2001

The evolution of the MHC-G gene does not support a functional role for the complete protein.

The study of the MHC-G gene evolution during nearly 40 million years does not support a role for the full molecule. The MHC-G-like proteins of New World monkeys are probably classical presenting molecules. Old World Cercopithecinae monkeys do not have a full MHC-G molecule and human individuals homozygous for the HLA-G null allele are healthy and do not show birth pathologies.

Amino Acid Sequence↗
PubMed2000

HLA-G, -E, -F preworkshop: tools and protocols for analysis of non-classical class I genes transcription and protein expression.

Non-classical MHC class I HLA-E, -F, and -G molecules differ from classical class I histocompatibility antigens by specific patterns of transcription, protein expression, and immunological functions. Restriction of the expression pattern of these non-classical antigens may play a key role in modulation of immune responses during pregnancy and diseases but remains to be additionally defined. A specific component of the second International Conference on HLA-G and the 13th HLA-G Histocompatibility Workshop will be dedicated to the analysis of transcription and expression of non-classical class I genes in normal and pathological tissues. In a first step, referred to as the preworkshop, we here report the analysis and conclusions of a working group which was constituted to gather and validate optimal reagents and protocols allowing RT-PCR analysis of HLA-E, -F, -G transcript levels and flow cytometry and immunochemistry analysis of HLA-G expression in cells and tissues. As a result of this work, use of specific primers and probes detecting alternative transcripts of HLA-E, -F, and G have been validated in transfected cells expressing differential pattern of HLA class I antigens. Analysis of the specificity and affinity of collected antibodies has allowed definition of reagents to be proposed for immunochemistry and flow cytometry analysis of HLA-G expression in normal and pathological tissues during the workshop. This work has allowed constitution of an extended workshop group which is now initiating analysis of non-classical class I transcription and expression in various cells and tissues, a collective contribution that will additionally refine our view of the expression of these antigens in normal and pathological situations.

Antibodies, Monoclonal↗
PubMed2000

Lack of MHC-G4 and soluble (G5, G6) isoforms in the higher primates, Pongidae.

HLA-G is a class Ib (nonclassical) major histocompatibility complex (MHC) protein expressed at the materno-fetal interface that may inhibit natural killer (NK) cell-mediated lysis in an allotype-independent manner. The human MHC-G transcript is differentially spliced, giving rise to at least six different forms. In order to study the evolutionary importance of this phenomenon, the presence of alternative splicing in MHC-G mRNA molecules from Pongidae (Chimpanzee, Gorilla, and Orangutan) has been investigated in the present work, and three alternative spliced isoforms (i.e.: G1, G2, and G3) have been found, but not the G4 and the soluble G5 and G6 ones. In addition, a novel MHC-G isoform is described in Gorilla, "G2 short." This molecule is similar to the G2 isoform, but it lacks 29 amino acids normally encoded by exon 4. Our findings suggest that soluble isoforms are not necessary for MHC-G function(s) in Pongidae or that MHC-G is not a functional protein, because G1 is not necessary for survival in humans and Cercopithecinae bear stop codons in MHC-G exon 3.

Animals↗
PubMed2000

Homozygous HLA-G*0105N healthy individuals indicate that membrane-anchored HLA-G1 molecule is not necessary for survival.

HLA-G is expected to play an important role during fetal development. Recently, a healthy individual homozygous for the HLA-G*0105N allele has been described, suggesting that HLA-G expression was not essential for fetal survival. We now report studies of one family with five healthy siblings homozygous for HLA-G*0105N, who had been normally delivered; three of these siblings were females who also had normal deliveries. In addition, HLA-G*0105N cDNA has been fully sequenced, and normal G1 membrane anchored protein cannot be translated since after the codon 130 cytosine deletion (exon 3) a reading frameshift is observed leading to the existence of premature stop codon at position 189 (beginning of exon 4). Other protein isoforms (G2, G3 and G6), all containing the leader peptide and the alpha1 domain, are possible and their messenger mRNAs were found; any of these may undertake the necessary HLA-G functions. Our data show that the membrane anchored HLA-G molecule is not necessary in either mother or fetus for a normal pregnancy and survival. Also, individuals homozygous for HLA-G*0105N are healthy and with no indications of immunodeficiency or autoimmunity.

Alleles↗
PubMed2000

HLA genes in Mexican Mazatecans, the peopling of the Americas and the uniqueness of Amerindians.

The HLA allele frequency distribution of the Mexican Mazatecan Indians (Olmec culture) has been studied and compared with those of other First American Natives and worldwide populations (a total of 12,100 chromosomes; 6,050 individuals from 59 different populations). The main conclusions are: 1) An indirect evidence of Olmec and Mayan relatedness is suggested, further supporting the notion that Olmecs may have been the precursors of Mayans; 2) Language and genetics do not completely correlate in microenvironmental studies; and 3) Peopling of the Americas was probably more complex than postulated by Greenberg and others (three peopling waves). Significant genetic input from outside is not noticed in Meso and South American Amerindians according to the phylogenetic analyses; while all world populations (including Africans, Europeans, Asians, Australians, Polynesians, North American Na-Dene Indians and Eskimos) are genetically related. Meso and South American Amerindians tend to remain isolated in the Neighbor-Joining, correspondence and plane genetic distance analyses.

Alleles↗
PubMed1999

Evolution of MHC-G in primates: a different kind of molecule for each group of species.

When MHC-G molecules in primates (New World and Old World monkeys, Anthropoids and humans) were compared phylogenetically, very different evolutionary patterns within each species were found; their molecules did not have a straight forward and linear development throughout the postulated evolutionary pathway of primates. The earlier New World monkeys (South America) had relatively more alleles and the polymorphism was placed in the T-cell receptor (TcR), NK receptors and antigen binding sites; MHC-G probably works as a classical class I presenting molecule in these monkeys. MHC-G intron 2 from New World monkeys does not show the typical 23 bp deletion found in all other more recent primate species. Thus, it is possible that MHC-G molecules in New World monkeys belong to a different lineage than the MHC from higher primates. Another early lineage, Eurasian Old World monkeys, shows stop codons at exon 3: MHC-G proteins lacking the alpha2 domain may functionally suffice or otherwise reading-through stop-codon translational mechanisms may exist, as shown for other genes. Orangutans show lower (but significant) polymorphism than New World monkeys at NK, TcR and antigen binding regions; gorilla and chimpanzee show very low polymorphism. Humans only show three different HLA-G proteins with changes not affecting NK, TcR or antigen binding sites. It is observed that the more exposed the mother to allogeneic fetuses (polygamy), the less polymorphic HLA-G is observed within a given species. The data are concordant with the postulated immune inhibitory function for MHC-G in Old World monkeys, anthropoids and humans both at placental and inflammatory level.

Amino Acid Sequence↗
PubMed1999

Evolutionary relationships between HLA-B alleles as indicated by an analysis of intron sequences.

The HLA-B locus is the most polymorphic of the class I genes encoded within the human major histocompatibility complex. This polymorphism is mainly located in exons 2 and 3, which code for the molecule's alpha1 and alpha2 domains and includes the antigenic peptide binding site. However, information about adjacent non-coding regions (introns 1 and 2) has not been extensively reported but could be very important in establishing an understanding of the evolutionary mechanisms involved in the polymorphism generation of HLA-B and the Mhc loci. In the present work, introns 1 and 2 of 14 HLA-B alleles are studied and their significance is discussed; 10 have been sequenced in our own laboratory and the other 4 have been previously reported by others. Different serological families share the complete intron 1 sequence; at this region, 12 out of 14 HLA-B alleles could be included in four groups with the same intron 1 sequence: a) B*0702, B*4201, B*4801; b) B*27052, B*4002, B*4011; c) B*40012, B*4101, including B*4501, B*5001 (these latter two alleles have specific characteristics in both introns 1 and 2, which may reflect a common evolutionary pathway); and d) B*44031, B*44032. The other alleles, B*1402, and B*1801, do not have identical intron 1 sequences compared to any of the described groups, but share many similarities with them. The B*1801 evolutionary pathway seems to be very specific since it branches separately from other alleles both in intron 1 and intron 2 dendrograms. On the other hand, HLA-B allelic group distribution and similarities according to intron 1 sequences were not confirmed when using intron 2, especially in the cases of B*4002, B*4101 and B*4801. This would suggest that both point mutations fixed by genetic drift and gene conversion events are involved in HLA-B diversification. The latter events could be supported by the strong homology between intron 1 and, to a lesser extent, intron 2, and also the CG content within them. Finally, the precise knowledge of these non-coding regions could be important for developing DNA base typing strategies for the HLA-B alleles.

Alleles↗
PubMed1999

HLA in the Azores Archipelago: possible presence of Mongoloid genes.

The HLA profile of the Azoreans has been compared with those of other world populations in order to provide additional information regarding the history of their origins. The allele frequencies, genetic distances between populations, correspondence analyses and most frequent haplotypes were calculated. Our results indicate that the Azorean population most likely contains an admixture of high-frequency Caucasoid, Mongoloid and, to a lesser degree, Negroid HLA genes. The middle Atlantic Azores Archipelago was officially colonized by the Portuguese after 1439 and historical records are concordant with the existence of Caucasoid and Negroid population. However, Mongoloid genes were not suspected, but the Oriental HLA haplotypes A24-B44-DR6-DQ1, A29-B21-DR7-DQ2 and A2-B50-DR7-DQ2 are the fourth, fifth and sixth most frequent ones in Azores. A correspondence analysis shows that the Azorean population is equidistant from Asian and European populations and genetic distances are in some cases closer to the Asian than to European ethnic groups, and never are significantly different; also, B*2707 subtype is found in Asians and Azoreans (but not in Europeans) and the same Machado-Joseph Disease founder haplotypes (Chr 14) are found in both Japanese and Azoreans. It is proposed that a Mongoloid population exists in Azores; whether, the arrival occurred prior to discovery is undetermined.

Alleles↗