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  • 1
    ISSN: 1420-9071
    Keywords: HLA ; haplotype ; disease ; diabetes ; arthritis ; Berger's disease
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Abstract Extended HLA haplotypes frequencies were estimated from the HLA, C2, Bf and C4 phenotypes of 74 patients with non-insulin-dependent diabetes (NIDD), 92 with juvenile rheumatoid arthritis (JRA), 44 with Berger's disease (BD), 83 with insulin-dependent diabetes (IDD), and 140 healthy controls. The extended HLA haplotype B18 CF130 DR3 DQw2, which is common (around 10% phenotype frequency) in healthy Spaniards and in other populations of paleo-North African origin, was found to be significantly less frequent in NIDD, JRA and BD, whereas its frequency was normal in IDD (although DR3 DQw2 haplotypes were increased in the latter disease). These data support the existence of a common HLA-linked pathogeneic mechanism in NIDD, JRA and BD, and point to a genetic difference between IDD and NIDD at the HLA level. This effect is readily detectable in our population because the uncommon BfF1 allele marks that haplotype instead of the more common BfS, which marks B8 CS01 DR3 DQw2 in other Caucasians. Our results support the hypothesis of strong selective pressures operating at the HLA level to preserve extended HLA haplotypes with advantageous gene sets from dilution by crossing-over. Imbalanced incomplete haplotypes may give rise to inappropriate T-cell repertoire selection in the thymus and/or antigen handling in the periphery, and be partly responsible for the pathogenesis of certain HLA-linked diseases (i.e. NIDD, JRA, and BD).
    Type of Medium: Electronic Resource
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  • 2
    ISSN: 1432-1211
    Keywords: Key words Basques ; Algerians ; Portuguese ; Spaniards ; HLA
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Abstract  HLA-A, -B, -DRB1, -DQA1, and DQB1 alleles were studied in Iberian and Algerian populations by serology and DNA sequence methodologies. The genetic and cultural relatedness among Basques, Spaniards, and paleo-North Africans (Berbers or Tamazights) was established. Portuguese people have also maintained a certain degree of cultural and ethnic-specific characteristics since ancient times. The results of the present HLA study in Portuguese populations show that they have features in common with Basques and Spaniards from Madrid: a high frequency of the HLA-haplotypes A29-B44-DR7 (ancient western Europeans), A2-B7-DR15 (ancient Europeans and paleo-North Africans), and A1-B8-DR3 (Europeans) are found as common characteristics. Portuguese and Basques do not show the Mediterranean A33-B14-DR1 haplotype, suggesting a lower admixture with Mediterraneans; Spaniards and Algerians do have this haplotype in a relatively high frequency, indicating a more extensive Mediterranean genetic influence. The paleo-North African haplotype A30-B18-DR3 present in Basques, Algerians, and Spaniards is not found in Portuguese either. The Portuguese have a characteristic unique among world populations: a high frequency of HLA-A25-B18-DR15 and A26-B38-DR13, which may reflect a still detectable founder effect coming from ancient Portuguese, i.e., oestrimnios and conios; Basques and Algerians also show specific haplotypes, A11-B27-DR1 and A2-B35-DR11, respectively, probably showing a relatively lower degree of admixture. A neighbor-joining dendrogram place Basques, Portuguese, Spaniards, and Algerians closer to each other and more separated from other populations. Genetic, cultural, geological, and linguistic evidence also supports the hypothesis that people coming from a fertile Saharan area emigrated towards the north (southern Europe, Mesopotamia, the Mediterranean Islands, and the North African coast) when the climate changed drastically to hotter and drier ca 10 000 years B.C.
    Type of Medium: Electronic Resource
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