Gene geography : a computerized bulletin on human gene frequencies最新文献

Blood group systems ABO, KEL, MN, RH, secretor status for ABH blood group substances, red cell enzymes ACP1, ESD, AK1, 6-PGD, PGM1 subtypes, serum markers GC, TF, PI, AHSG, ORM1 and chromosomal heteromorphism Q, C, DA/DAPI were examined in a population sample of the Garfagnana, a semi-isolated mountainous area in the province of Lucca (Tuscany, Italy). The total sample was subdivided and analysed according to the more recent historical events which have occurred in Garfagnana. The observed phenotype and gene frequencies were discussed in the context of other population samples from the same province and of the same region. As a whole, the results concur in pointing out a certain degree of heterogeneity within the area and a high differentiation from the rest of Tuscany. Such peculiar genetic features of the population have to be related to the historical, geographic and cultural isolation of the Garfagnana.

12 population groups of Hungary, 1514 individuals altogether, have been studied for polymorphisms of alpha 1antitrypsin, serum cholinesterase, paraoxonase and delta-aminolevulinic acid dehydrase, N-acetyltransferase variation and aldehyde dehydrogenase deficiency. A possible relationship between their allele frequencies and environmental factors in the context of ecogenetic and pharmacogenetic phenomena in Hungary is discussed.

Serum samples of autochthonous individuals from the Garrotxa prepyrenean region, and the Pallars Sobirà valley were screened for HP (Haptoglobin) and ORM (Orosomucoid) types by polyacrylamide isoelectric focusing and electrophoresis. The allele frequencies estimated were HP*1 = 0.3902 and ORM1*S = 0.3697 for Pallars Sobirà, and HP*1 = 0.4161 and ORMS1*S = 0.3691 in the Garrotxa. While our results for the HP system are within the range of variation of the Iberian Peninsula, the ORM1 protein shows a remarkable degree of variation among these populations.

HP, GC and PI polymorphisms have been typed on 16 Central Indian tribal populations with a total of 1658 individuals. The distribution of allele frequencies shows a statistically highly significant heterogeneity, which may be caused by several microevolutionary factors, such as genetic drift, social and geographic isolation. Some new variants were observed in both the GC system (GC 2Cmah) and in the PI system (PI Yori). The PI variants are more frequent and are found in most of the 16 populations under study whereas the GC variants are rather infrequent and restricted to only three populations.

Autochthonous human samples of the three westernmost islands of the Canarian Archipelago, La Palma, Gomera, and Hierro, have been analyzed for eight red cell polymorphic enzymes. Only a small intra and inter-insular differentiation exists among these three islands. However, a marked heterogeneity is found when all seven islands of the Archipelago are compared by Nei's genetic distances [1972]. Nevertheless, there is no correlation between genetic and geographic distances. Historical factors could explain the frequency similarities of some distant islands. The rare variant GD*A+Negroid allele, and the endemic GD*Gc allele, previously found in other islands, have also been detected in this survey.

Polymerase chain reaction (PCR) amplification and oligonucleotide probe hybridization may be used to detect DNA polymorphisms rapidly in large samples. In this study, 475 individuals from thirteen human populations were allelotyped at the human leukocyte antigen (HLA) DQa (DQA1) locus. A 242 or 239 bp fragment was amplified from each individual's DNA. Each of six alleles was detected by hybridization to allele specific oligonucleotide probes (ASOs). Allelic frequencies varied between populations, but the measure of gene frequency variation among populations, the FST value, was relatively low. Most populations had genotypic frequencies in agreement with Hardy-Weinberg equilibrium expectations. Principal component analysis was performed on the populations, and results are presented in graphic form. The heterozygosity at this locus is high in all populations; the average (74%) is close to the theoretical maximum (83%) for a 6 allele system. It is likely that this system is affected by stabilizing selection, which makes it less than optimal for the study of random evolutionary divergence between populations.

Tharus--a population of Terai (a region with a severe malarial morbidity in the past)--can be subdivided into three main groups: Western, Central and Southern Tharus. They have usually been considered a Mongoloid population and this has been further substantiated by mtDNA findings on Central Tharus. Studies on the distribution of malaria-related genes have shown an extremely high frequency (0.8) of the alpha-thal gene among Western and Central Tharus. This frequency, however, unexpectedly turned out to be only 0.04 in a sample of Eastern Tharus. This raised doubts on the common notion that Tharus are a single anthropological entity. In the present investigation mtDNA markers were studied in the same sample of Eastern Tharus previously examined for the alpha-thal gene. The findings were: 1. the same three features which confirmed the classification of Central Tharus as Mongoloids (i.e., the common occurrence of HpaI-1/HincII-1 and HaeII-5 morphs, and the lack of BamHI polymorphism) were also present in this sample. Since the only neighbouring population accessible to Tharus, until recently, has been Hindu (Caucasoids), this result strongly supports the notion that Tharus are indeed a single anthropological entity; 2. two statistically significant differences between Eastern and Central Tharus--namely, a much higher HaeII morph 5 frequency among Central Tharus, and the absence in the same group of the mutation at 15.487 bp (very common among Eastern Tharus)--together with the results on alpha-tal gene, suggested that Tharu subgroups underwent an effective reproductive isolation.

The polymorphisms of mitochondrial DNA (mtDNA) for the restriction enzymes HpaI, BamHI, HaeII, MspI, AvaII, and HincII were studied in a sample of 147 unrelated Indian individuals from South Africa, who were subdivided according to religion and language into four groups, namely, Tamil, Hindi, Gujerati and Moslem. They were found to be monomorphic with the enzymes BamHI, and HaeII, and little variation was observed with the enzymes MspI and HincII. Six individuals were found to contain the non-Caucasoid HpaI morph, HpaI-3, which is found more commonly in indigenous African populations. This suggests that some flow of maternal genes from indigenous African populations into the Indian population may have occurred. Despite these interactions, Indians in South Africa display very little mtDNA variation (F = 0.77) when compared with those living in Nepal (F = 0.35) and New Delhi (F = 0.51). When compared with other Caucasoid populations, Indians are more homogenous in their genetic structure, which may be attributable to the high level of inbreeding among them, due to strict caste endogamy and certain religious customs that are still practised by the majority of Indians today.

Four plasma protein polymorphisms: Group specific Component (GC), Haptoglobin (HP), Transferrin (TF) and Caeruloplasmin (CP), have been determined in two endogamous populations (Mala and Madiga) of Visakhapatnam of Coastal Andhra Pradesh, South India. The results were compared between the two caste populations and they revealed no significant differences. The results were also compared with those available from other Andhra populations.