The HLA-G gene displays several peculiarities that are distinct from those of classical HLA class I genes. The unique structure of the HLA-G molecule permits a restricted peptide presentation and allows the modulation of the cells of the immune system. Although polymorphic sites may potentially influence all biological functions of HLA-G, those present at the promoter and 3′ untranslated regions have been particularly studied in experimental and pathological conditions. The relatively low polymorphism observed in the MHC-G coding region both in humans and apes may represent a strong selective pressure for invariance, whereas, in regulatory regions several lines of evidence support the role of balancing selection. Since HLA-G has immunomodulatory properties, the understanding of gene regulation and the role of polymorphic sites on gene function may permit an individualized approach for the future use of HLA-G for therapeutic purposes.

Three separate and parallel North American Carduelis evolutionary radiations have been identified. North American siskin radiation (starting about 2.7 million years ago) comprises siskin, Antillean siskin, black-capped siskin, pine siskin and pine siskin perplexus. C. spinus could have passed to America through the Beringia or Greenland coast and, during Pliocene Epoch, reached the Antilles and evolved into Antillean siskin (C. dominicensis), endemic to Hispaniola Island. It is ancestor of pine siskin. Pine Siskin, also a sister taxon of C. spinus, thrives in North America from Alaska to Guatemala since about 0.2 MYA. It lives below the Mexican Isthmus in the highlands from northern Chiapas (Mexico) to western Guatemala. Black-capped siskin (C. atriceps) is a sister species of C. spinus, with which it shares habitat and territory. C. pinus green-backed morphs may have been mistaken by C. atriceps which is a grey-backed finch. Mesoamerican goldfinch radiation (starting about 5 million years ago) includes C. tristis (American goldfinch), C. psaltria (lesser goldfinch) and C. lawrencei (Lawrence's goldfinch). They all thrive in western United States and Mexico, down to northern South America. C. psaltria is a North American bird that colonized South American habitats to North Peru and evolved into darker head and back while going southwards. South American siskin radiation started about 3.5 million years ago; parental C. notata thrives in Mexican mountains and successfully colonized South America, giving rise to this radiation. South American Carduelis radiation occurred only when mesothermal plants from the Rocky Mountains invaded the Andean spine after emergence of the Panama Isthmus.

Amerindian Mapuche (Araucanians) are now living in Chile and Argentina at both sides of Andean Mountains. They are anthropologically and genetically different from southernmost South America Patagonian Amerindians. Most of the HLA alleles found in our Mapuche sample are frequent or very frequent in North and South America Amerindians: (1) Class I: A*02:01, A*03:01, A*68:01, B*39:09, B*51:01, (2) Class II: DRB1*03:01, DRB1*04:03, DRB1*07:01, DRB1*08:02, DRB1*14:02, DRB1*16:02. One of the nine most frequent extended haplotypes seems to be from European origin, suggesting the existence of a degree of admixture with Europeans in our Mapuche sample. It has been calculated of about 11 % admixture. Three of the extended haplotypes are also found in other Amerindians and five of them are newly found in Mapuche Amerindians: A*68:01-B*39:09-DRB1*08:02-DQB1*04:02; A*68:01-B*51:01-DRB1*04:03-DQB1*03:02; A*29:01-B*08:01-DRB1*03:01-DQB1*02:01; A*02:01-B*15:01-DRB1*04:03-DQB1*03:02; A*33:01-B*14:02-DRB1*07:01-DQB1*03:03. The medical importance of calculating HLA profile is discussed on the diagnostic (HLA and disease) and therapeutical bases of HLA pharmacogenomics and on the construction of a virtual transplantation HLA list profile. Also, anthropological conclusions are drawn.

HLA genes (class I and II) have been studied in a Kurd population from Iran (North West towns of Saqqez and Baneh, close to Irak border). Kurds speak an Iranian language. HLA Kurd profile has been compared with those of Central Asians, Siberians, Mediterraneans and other worldwide populations; a total of 7746 chromosomes were used for computer comparisons. Both Neighbor-joining and correspondence genetic analyses place Kurds in the Mediterranean population cluster, close to Iranians, Europeans and Caucasus populations (Svan and Georgian). New extended HLA haplotypes are described, being A*02:01-B*35:01-DRB1*01:01-DQB1*05:01 and A*24:02-B*18:09-DRB1*11:01- DQB1*03:01 the most frequent ones; other Kurd extended haplotypes are also found in Azeris and Palestinians. This research work may be useful for: 1) future Iranian Kurds transplantation regional programs, 2) HLA pharmacogenomics in order to practise a preventive Medicine and drug side effects, and 3) Epidemiology of HLA-associated diseases in Kurds.

We describe the analysis of the Major Histocompatibility Complex (MHC) class II polymorphism in Mexican Mestizo population. The study provides the HLA-DRB1, DQA1 and DQB1 allele frequencies in 99 Mexican Mestizos. DNA from these individuals was typed by PCR followed by hybridization using sequence specific oligonucleotides (PCR-SSO). The relationship with other worldwide populations was studied by using HLA data from 69 different populations and calculating neighbor-joining dendrograms and correspondence multidimensional values. The highest frequencies were for DRB1*0802 (allele frequency = 0.151), DRB1*0701 (allele frequency = 0.111) and DRB1*0407 (allele frequency = 0.106). Among the eight DQA1 alleles detected, the most frequent were DQA1*03011 (allele frequency = 0.257), DQA1*0501 (allele frequency = 0.227) and DQA1*0401 (allele frequency = 0.166). Twelve DQB1 alleles were found and four of them, DQB1*0302 (allele frequency = 0.237), DQB1*0301 (allele frequency = 0.176), DQB1*0201 (allele frequency = 0.166) and DQB1*0402 (allele frequency = 0.166) showed the highest frequencies. The haplotype DRB1*0802-DQA1*0401-DQB1*0402 (0.151) predominated clearly, followed by DRB1*0701-DQA1*0201-DQB1*0201 (0.111) and DRB1*0407-DQA1*03011-DQB1*0302 (0.101). Both genetic distances and correspondence analyses showed that Mexicans clustered with Amerindian population. These results suggest that the Mexican Mestizo population be principally characterized by haplotypes presents in Amerindian and Caucasian populations with a low frequency of Black haplotypes. In summary, the HLA class II haplotype frequencies demonstrated the tri-racial component existing in Mexican Mestizos.