Genetic response to an environmental pathogenic agent: HLA-DQ and onchocerciasis in northwestern Ecuador

The aim of this study is to explore human leukocyte antigen (HLA)-DQ variability in two populations (Cayapas Amerindians and Afro-Ecuadorians) who live near one another along the Cayapa River and who are exposed to the same environmental stresses, such as infection by Onchocerca volvulus. HLA-DQA1 and HLA-DQB1 of 149 unrelated individuals (74 Cayapas and 75 Afro-Ecuadorians) have been analyzed. HLA high-resolution molecular typing was performed by sequence-based typing, sequence-specific oligonucleotides hybridization and sequence-specific primer (SSP) amplification. The comparison between affected (cases) and unaffected people (controls) in both populations shows the key role of several HLA-DQA1 alleles in susceptibility and protection against onchocerciasis. In both populations, there is strong evidence related to the protective role of DQA1*0401 against onchocerciasis. Alleles HLA-DQA1*0102 and *0103 seem to represent risk factors in Afro-Ecuadorians, while HLA-DQA1*0301 is only a suggestive susceptibility allele in Cayapas. These findings represent new positive/negative associations with onchocerciasis in South America, whereas previous findings pertained only to African populations.

COL1A2 (type I collagen) polymorphisms in the Colorado Indians of Ecuador

BACKGROUND

EcoRI, MspI and RsaI restriction fragment length polymorphisms (RFLPs) of the COL1A2 (type I collagen) gene are proving to be extremely informative markers for describing human populations; therefore they hold considerable potential for anthropogenetic research.

AIM

The objective of this study was to characterize at the DNA level the Colorado Indians from Ecuador, for whom only blood group frequency information is available, and to investigate their relationships with the Cayapa-another Ecuadoran Native American group belonging to the same linguistic affiliation-and other world populations.

SUBJECTS AND METHODS

Colorado Indians (n = 80) were analysed for the three anthropologically informative RFLPs of the COL1A2 gene. To better define the genetic relationship between this group and other populations, principal component analysis (PCA) was performed and genetic distances were estimated. Population genetic structure was tested through analysis of molecular variance (AMOVA) by comparing haplotype frequencies.

RESULTS

COL1A2 allele and haplotype frequencies showed a certain degree of heterogeneity between the two Chibchan populations of Ecuador. The AMOVA test detected a significant level of differentiation (Fst = 0.034, p = 0.0049) between Colorado and Cayapa Indians. PC and genetic distance analyses showed a clear-cut separation between African and non-African populations; within the latter, the two Native American groups were differentiated from each other.

CONCLUSIONS

The present findings suggest the presence of a low level of genetic relatedness between the Colorado and the Cayapa, despite their supposed common ethnogenesis. This confirms what has been inferred from other genetic data about the high degree of heterogeneity among Native Americans, even within the same linguistic branch, thus supporting the existence of genetic sub-structure within the central and southern American populations.

An analysis of peroxisome proliferator-activated receptor gamma (PPAR-gamma 2) Pro12Ala polymorphism distribution and prevalence of type 2 diabetes mellitus (T2DM) in world populations in relation to dietary habits

BACKGROUND AND AIM

The human peroxisome proliferator-activated receptor gamma (PPAR-gamma) is involved in lipid storage, glucose homeostasis and adipocyte differentiation. The Ala allele of the Pro12Ala polymorphism has been associated with a protective effect against T2DM. Ala allele frequencies are known for many populations, but data are absent for other interesting human groups.

METHODS AND RESULTS

We examined samples from Ethiopia, Benin, Ecuador and Italy. In addition, we performed an analysis of the Pro12Ala polymorphism distribution in world populations, also in relation to T2DM prevalence and the diet lipid content. In the European populations, the Ala allele frequencies are distributed according to a latitudinal trend, with the highest in the northern and central European populations and the lowest in the Mediterranean populations. Considering the world populations, a significant inverse relationship between Ala frequency and T2DM prevalence was observed mainly in populations where energy from lipids exceeded 30% of the total energy intake.

CONCLUSION

Northern Europe's cold climate has been hypothesised to have played a role in contributing to the present pattern. Moreover our analysis appears to confirm, at a population level, the protective effect of Ala allele against T2DM, already observed in case-control studies, but only in populations with a diet rich in lipids.

Estrogen receptor alpha polymorphisms and fertility in populations with different reproductive patterns

The estrogen receptor (ER) plays an important role in mediating estrogen action on target tissues. ER-alpha, the most abundant, is found in all human reproductive tissues and studies on alpha-ER knockout mice have highlighted its role in reproduction. ER-alpha gene (ESR1) polymorphisms have been associated with a variety of disorders including human infertility. In this study, we examined the association of ESR1 PvuII and XbaI polymorphisms with fertility in two populations with different reproductive patterns and precisely in a sample of healthy Italian men and women (n=178) and in a sample of healthy African-Ecuadorian women (n=57). ESR1 xx and ppxx genotypes among the Italian men were found to be associated with an above-median number of children (P=0.01 and P=0.004, respectively). ESR1 pp genotype among the Italian women showed a tendency to be associated with a lower number of abortions (P=0.04), whereas ESR1 pp and ppxx genotypes among African-Ecuadorian women were associated with a higher number of children (P=0.02 and P=0.03, respectively). These results are consistent with previous observations indicating a role of ESR1 genotypes in human infertility and give insight into the complex interactions between genotypes and reproductive behaviours in human populations.

Apolipoprotein E polymorphism and fertility: a study in pre-industrial populations

Human apolipoprotein E is the most important supplier of the cholesterol precursor for steroid hormone production in steroidogenic tissues and therefore could play a role in the regulation of steroid hormone function and influence human reproduction. This hypothesis has been confirmed by studies describing a differential fertility associated with common apolipoprotein (APOE) genotypes in two European populations. In the present investigation the impact of APOE genetic variation on fertility was studied in two Ecuadorian populations, African-Ecuadorians (57 women) and Cayapa Indians (27 women). In addition some biodemographic variables concerning women's fertility were investigated (124 African-Ecuadorian women; 40 Cayapa women) to better understand the APOE-fertility relationships in these pre-industrial populations. General fertility rates in both populations were very high (6.5 and 6.2 for the African-Ecuadorians and for the Cayapa respectively). When considering only women near the end of reproductive life (>/=40 years), a more marked difference was observed between the two groups (9.1 versus 7.7, P=0.09). In both communities, the highest number of children was found to be associated with the e*4/e*3 genotype; the e*4/e*3 genotype frequency (0.50) in the African-Ecuadorian women with 9-17 children was about three times that of the women with 0-8 children (0.14) (P=0.02). The present findings are at variance with those observed in European populations, where e*3/e*3 was the genotype associated with the highest reproductive efficiency. A possible explanation for this inconsistency could be due to the different functional properties associated with the e*3 and e*4 alleles and to genotype interactions with environmental factors including reproductive strategies.

Genetic variation atapolipoprotein E locus in Ethiopia: an E5 variant corresponds to two different mutant alleles: E*5 (Glu212Lys) and E*5 (Gln204Lys; Cys112Arg)

A previous investigation on apolipoprotein E polymorphism in the Ethiopian population highlighted the presence of a further variant allele named E*5 in addition to the three common alleles. The variant is considered rare elsewhere but has a frequency of more than 1% in this population. Now characterized by gene sequencing and restriction isotyping in many members of the families of the original carriers, the variant isoform has actually been found to be determined by two different gene mutations. Effectively rare in Ethiopians, one of the two, E5 (Gln204Lys, Cys 112Arg), has never been described before. The other, E5 (Glu212Lys), previously described in a subject of Turkish origin, is present at the polymorphic level only in the Ethiopian population. No subjects bearing these variants had anomalous lipid or apolipoprotein patterns. In the course of the present investigation both have been found to occur as rare variants in the southern Italian population as well. The occurrence of the two variants in the populations of Ethiopia and of the Mediterranean basin could be explained by taking into account the relevant Caucasoid contribution to the Ethiopian gene pool.

New Data on the World Distribution of Paraoxonase ( PON1 Gln 192--Arg) Gene Frequencies

The physiological role of human paraoxonase (PON), a serum enzyme that hydrolyzes organophosphate insecticides and nerve agents, is not clear. Of the three genes in the paraoxonase gene family, PON1 shows a polymorphism, Gln 192 --> Arg, governed by two common alleles named *Q and *R. These determine two different isoforms associated, respectively, with lower and higher activity towards paraoxon, a toxic metabolic product of the insecticide parathion. The *R allele has often been found associated with an increased risk of coronary heart disease. As human populations tend towards greater exposure to environmental changes, including changes in dietary habits and contact with insecticides or other toxic substances, health risks will change as well. In studying the prevention of these newly emerging risks, it could be important to know the distribution of the two alleles in the various world populations. In this paper we report on the genotype and allele frequencies of this polymorphism in different populations, most of which have never been examined for this polymorphism. Samples were taken from mainland Italy, Sardinia, Ethiopia, Benin, and Ecuador. The *R allele frequencies for the samples were: 0.313, 0.248, 0.408, 0.612, and 0.789, respectively. The data show a large variability in allele frequencies, and, in particular, that PON1 allele distribution depends on membership to different geographic populations.

Analysis of three RFLPs of the COL1A2 (Type I Collagen) in the Amhara and the Oromo of Ethiopia

BACKGROUND

The present composition of the Ethiopian population is the result of a complex and extensive intermixing of different peoples of North African, Near and Middle Eastern, and south-Saharan origin. The two main groups inhabiting the country are the Amhara, descended from Arabian conquerors, and the Oromo, the most important group among the Cushitic people. With the exception of some surveys on the general Ethiopian populations, little is known about the degree of genetic differentiation between the Amhara and the Oromo.

AIM

The study seeks to investigate the genetic structure of these two heterogeneous Ethiopian populations and to characterize their relationships with other African and Mediterranean peoples.

SUBJECTS AND METHODS

Amhara and Oromo individuals (n = 171) were analysed for three RFLPs (restriction fragment length polymorphisms) of the COL1A2 gene. To better define the genetic relationship between the two Ethiopian groups, and also between African and non-African peoples, genetic distances among Amhara, Oromo and other populations were estimated using the COL1A2 allele and haplotype frequencies, and the allele frequencies of 16 additional classical markers.

RESULTS

chi(2) analysis applied to the COL1A2 allele and haplotype frequencies showed a small but statistically significant degree of heterogeneity between the two Ethiopian populations. Combining the information obtained from the three RFLP markers, a significant level of differentiation (Fst = 0.0147, p = 0.036) was also detected between Amhara and Oromo. The genetic distance analysis showed the separation between African and non-African populations, with the Amhara and Oromo located in an intermediate position. This pattern is consistent with the location of the two Ethiopian groups in other genetic analysis and with cultural data.

CONCLUSIONS

The present findings suggest the presence of a differential level of genetic relatedness with south-Saharan peoples in the two Ethiopian groups, which could reflect their different history and seems to indicate the existence of genetic sub-structure within the country.

Red cell enzyme polymorphisms in Friuli Venezia Giulia (northeast Italy)

Seven erythrocyte enzyme polymorphisms (ACP1, ADA, ESD, GLO1, PGD, PGM1 and PGM2) were investigated in a sample of 673 unrelated adult individuals from Friuli Venezia Giulia (or Friuli) and Istria. The gene frequencies found in the four provincial samples of Friuli and Istria fall within the range previously reported for Italy, showing a genetic homogeneity among the considered samples. However, comparisons with data from ex-Yugoslavian samples--using the chi 2 test--showed rather marked differences, probably due to a real different genetic structure of the compared samples. A significant association was found assuming a linear relation between the ADA*2 allele frequencies and longitude (r = +0.5503) and between the PGD*C frequencies and latitude (r = -0.6483), suggesting the existence of a clinal trend for these allele frequencies in Italy. These results seem to disagree with foregoing conclusions stated by other authors, probably because these studies were carried out in an area either rather narrow from the geographical point of view or affected by small size migration movements.

mtDNA history of the Cayapa Amerinds of Ecuador: detection of additional founding lineages for the Native American populations

mtDNA variation in the Cayapa, an Ecuadorian Amerindian tribe belonging to the Chibcha-Paezan linguistic branch, was analyzed by use of hypervariable control regions I and II along with two linked regions undergoing insertion/deletion mutations. Three major maternal lineage clusters fit into the A, B, and C founding groups first described by Schurr and colleagues in 1990, whereas a fourth lineage, apparently unique to the Cayapa, has ambiguous affinity to known clusters. The time of divergence from a common maternal ancestor of the four lineage groups is of sufficient age that it indicates an origin in Asia and supports the hypothesis that the degree of variability carried by the Asian ancestral populations into the New World was rather high. Spatial autocorrelation analysis points out (a) statistically significant nonrandom distributions of the founding lineages in the Americas, because of north-south population movements that have occurred since the first Asian migrants spread through Beringia into the Americas, and (b) an unusual pattern associated with the D lineage cluster. The values of haplotype and nucleotide diversity that are displayed by the Cayapa appear to differ from those observed in other Chibchan populations but match those calculated for South American groups belonging to various linguistic stocks. These data, together with the results of phylogenetic analysis performed with the Amerinds of Central and South America, highlight the difficulty in the identification of clear coevolutionary patterns between linguistic and genetic relationships in particular human populations.

Bioelectrical impedance analysis and anthropometry in Ecuadorian children of African ancestry

In the city of Esmeraldas, north-western coast of Ecuador, height, weight, and body composition of 600 male and female schoolchildren of African ancestry in the age groups four, five and six years were investigated. All the children were apparently healthy without any obvious or reported pathologies and in accordance with data from personal information were assigned to one of two socio-economic classes. The greater values for weight and height shown by children in the higher socio-economic group than in the less well off are compatible with those for more fat and water as obtained by the BIA investigation. Additional information on nutritional, muscular and general health status was obtained from positioning and degree of dispersion of the 'Biagram' ellipses. It seems that both the anthropometric and the bioelectrical impedance methods provide useful information on the differences due to belonging to one or other of the socio-economic groups.

Biodemography in Siena, Italy

Data were obtained on surnames of the parents and places of birth of the parents and grandparents of children in Siena, Italy. Isonymy and total inbreeding coefficient, and their random and non-random components, are 0.005, 0.00125, 0.00019 and 0.00106, respectively. Isonymy and inbreeding figures are similar to those of other medium-sized Italian towns, while higher values have been reported for Italian villages and Italian ethnic minorities. City endogamy, and endogamy of Contrada for grandparents have the same values (44.1 and 44.8%, respectively), but for parents, endogamy of Contrada is lower than city endogamy (15.2 and 33.4%, respectively). The difference between the extent of Contrada endogamy expected at random and observed in the parents' generation does not seem to affect the genetic structure of the present population. However, the bulk of marriage migration (more than 70%) is short range, with people coming from Tuscany. There is no statistical difference in marital migration between males and females.

Genetic history of the population of Sicily

We investigated the genetic heterogeneity of 2354 individuals from the 9 provinces of Sicily. The genetic markers we used were HP, GC, TF, PI, and AK1 plus other previously tested polymorphisms, for a total of 24 independent markers. Distinct multivariate statistics were applied to verify the claimed genetic distinctiveness between extant eastern and western Sicilian populations. Our hypothesis stated that any diversity found between the two subpopulations would represent the signature of early colonization of the island by Greek and Phoenician peoples. Correspondence analysis showed that there was no clear geographic clustering within Sicily. The genetic distance matrix used for identifying the main genetic barriers revealed no east-west differences within the island's population, at least at the provincial level. FST estimates proved that the population subdivision did not affect the pattern of gene frequency variation; this implies that Sicily is effectively one panmictic unit. The bulk of our results confirm the absence of genetic differentiation between eastern and western Sicilians, and thus we reject the hypothesis of the subdivision of an ancient population in two areas.

GM and KM allotypes in nine population samples of Sicily

Serum samples of 864 unrelated healthy male and female individuals belonging to nine provinces of Sicily were types for Glm (1,2,3,17), G3m (5,10,11,13,14,15,16,21), and KM (1). With the exception of the Trapani sample these samples are characterized by the presence of five GM haplotypes: GM*1,17;21,26; GM*1,2,17;21,26; GM*1,3;5,10,11,13,14,26; GM*3;5,10,13,14,26; and GM*1,17;10,11,13,15,16. The interpopulation variability in the distribution of these haplotypes is considerable, which is especially due to haplotypes GM*1,3;5,10,11,13,14,26, and GM*3;5,10,13,14,26. However, no clear-cut clustering of the samples according to historical or geographical facts could be shown. Comparisons with other Italian populations reveal the considerable genetic difference of the Sicilians, which is in particular caused by the presence of the haplotypes GM*1,3;5,10,11,13,14,26, and GM*1,17;10,11,13,15,16. These haplotypes are quite uncommon in Europeans and may reflect gene flow from the Middle East. The KM phenotype and allele frequencies also show a considerable interpopulation variability among the nine Sicilian samples, but as for GM no distinction between eastern and western provinces of Sicily is present.

Increase of chromosomal aberrations induced by ionising radiation in peripheral blood lymphocytes of civil aviation pilots and crew members

This study inquires if there is an increase of chromosomal aberrations by ionising radiation of cosmic origin in civil pilots and flight-crew members. Totals of 37,208 exposed cells and 10,950 control cells, from 192 and 55 donors respectively, were scored averaging 200 observations per subject. The analysis showed the increase of dicentric and ring chromosomes in peripheral blood lymphocytes of the flight personnel. The difference of the total aberration frequencies between exposed and control was statistically significant.

Apolipoprotein B and E genetic polymorphisms in the Cayapa Indians of Ecuador

Three DNA polymorphisms (XbaI, EcoRI, and Ins/Del) of the apolipoprotein B (APOB) gene and the CfoI polymorphism of the APOE gene were investigated in a sample of 96 Cayapa Indians from Ecuador. The frequencies of the X+ (0.182), R+ (1.000), and Del alleles (0.432) at the three APOB sites were found to be higher than and to differ significantly from those reported for East Asians. No comparisons could be made between the Cayapa and other native Americans because of the lack of data on these sites. We observed in our sample that, like native American populations but unlike East Asians, the APOE allele frequencies were characterized by the absence of the APOE*2 allele and by a high frequency of the APOE*4 allele (0.280). Besides a probable drift effect, the high APOE*4 value was tentatively attributed to an effect of selection. Because this allele enhances the absorption of cholesterol by the intestine, it could confer an advantage to carriers in an unfavorable environment (i.e., diet poor in cholesterol).

The Cayapa Indians of Ecuador: a genetically isolated group with unexpected complement C7 M/N allele frequencies

The Cayapa Indians live in north-western Ecuador in close proximity to a Black population of African ancestry. C7 M/N allotyping has proved to be a good technique for plasma genetic analysis in several populations. Investigation of 124 Cayapa plasma samples revealed the highest allele frequency of C7*N observed in any population examined so far (0.36 versus 0.225 or lower). The marked difference in frequency compared with several Oriental populations, which are believed to have been derived from the same Asian population as native Amerindians, may reflect the effect of a small founder population followed by a high degree of genetic isolation. The allele frequency of 0.12 for C7*N determined for the neighbouring Black population supports the conclusion that there has been a lack of genetic admixture of Cayapas with other populations, confirming the results of ethnohistorical investigations and other protein polymorphism studies.

Plasma protein polymorphisms (HP; TF and GC subtypes) in Friuli Venezia Giulia (northeast Italy)

Plasma protein genetic polymorphisms (HP; TF and GC subtypes) were studied in two different areas (Friuli Venezia Giulia and Istria). The results are discussed and compared with those reported by literature on other Italian and ex-Yugoslav population samples.

Genetic history of the population of Puglia (southern Italy)

Nine-hundred and twenty-two individuals belonging to the five provinces of Puglia were typed for nine erythrocyte genetic markers (ACP1, ADA, AK1, ESD, GLO1, PGD, PGM1, PGM2, and SODA). Genetic heterogeneity within Puglia was investigated on the basis of allele frequencies of the above mentioned markers plus ABO*A, ABO*B, ABO*O, and RH*D, by the (chi 2 test and Rst statistic. The analyses revealed no differences at the provincial level. Furthermore, correspondence and genetic distance analyses were applied to look for a statistical difference within Puglia from different standpoints, as well as between Puglia, the rest of Italy and other European and Near and Middle Eastern populations whose genetic history is most likely related. Southern and central Italian, Greek and Aegean populations appeared very homogeneous and quite differentiated from the rest of Europe, both continental (including northern Italy) and south-eastern, stressing the major impact of the heavy Greek colonization on the genetic pools of the circum-Mediterranean people.

EcoRI, RsaI, and MspI RFLPs of the COL1A2 gene (type I collagen) in the Cayapa, a Native American population of Ecuador

EcoRI, RsaI, and MspI RFLPs of the COL1A2 gene were analyzed, using the polymerase chain reaction technique, for the first time in a native American population: the Cayapa of Ecuador. These polymorphisms recently turned out to be good anthropological markers, both at the allele and at the haplotype frequency level. These data underline the well-known genetic affinity between the Cayapa and Asian populations. Moreover, our data on DNA polymorphisms agree with the indication of extremely low, if any, gene flow into the Cayapa gene pool from the neighboring black community, as already suggested not only by cultural data but also by protein polymorphisms.

Genetic relationships among the Native American populations

Red cell antigen data were used to investigate the genetic relationship among the Native American populations and their affinities with Siberian and Eastern Asian populations. Correspondence analysis showed a clear subdivision of all the Native American populations into three clear-cut clusters corresponding to the three linguistic families (identified by Greenberg)--Amerind, Na-Dene and Eskimo-Aleut. This result, as well as the close genetic resemblance between the Eskimos and the Asian populations, support the conclusion that the Americas were populated during at least three distinct and subsequent migration waves of people coming from Asia.

Analysis of HLA class II haplotypes in the Cayapa Indians of Ecuador: a novel DRB1 allele reveals evidence for convergent evolution and balancing selection at position 86

PCR amplification, oligonucleotide probe typing, and sequencing were used to analyze the HLA class II loci (DRB1, DQA1, DQB1, and DPB1) of an isolated South Amerindian tribe. Here we report HLA class II variation, including the identification of a new DRB1 allele, several novel DR/DQ haplotypes, and an unusual distribution of DPB1 alleles, among the Cayapa Indians (N = 100) of Ecuador. A general reduction of HLA class II allelic variation in the Cayapa is consistent with a population bottle-neck during the colonization of the Americas. The new Cayapa DRB1 allele, DRB1*08042, which arose by a G-->T point mutation in the parental DRB1*0802, contains a novel Val codon (GTT) at position 86. The generation of DRB1*08042 (Val-86) from DRB1*0802 (Gly-86) in the Cayapa, by a different mechanism than the (GT-->TG) change in the creation of DRB1*08041 (Val-86) from DRB1*0802 in Africa, implicates selection in the convergent evolution of position 86 DR beta variants. The DRB1*08042 allele has not been found in > 1,800 Amerindian haplotypes and thus presumably arose after the Cayapa separated from other South American Amerindians. Selection pressure for increased haplotype diversity can be inferred in the generation and maintenance of three new DRB1*08042 haplotypes and several novel DR/DQ haplotypes in this population. The DPB1 allelic distribution in the Cayapa is also extraordinary, with two alleles, DPB1*1401, a very rare allele in North American Amerindian populations, and DPB1*0402, the most common Amerindian DPB1 allele, constituting 89% of the Cayapa DPB1.(ABSTRACT TRUNCATED AT 250 WORDS)

Genetic characterization of the Cayapa Indians of Ecuador and their genetic relationships to other Native American populations

One-hundred sixty-four Cayapa Indians living in the Esmeraldas Province (northwest Ecuador) were studied for several erythrocyte genetic markers (ACP1, ADA, AK1, CA2, ESD, GLO1, G6PD, PGD, PGM1 subtyping and thermostability, PGM2, SODA, and HB). The Cayapa show allele frequencies typical of those of South American Indians. The absence of the CA2*2, G6PD*A, G6PD*A-, HBB*S, and HBB*C alleles and the low PGM1*1A and PGM1*2A and high PGM1*1B allele frequencies indicate that very little (no more than 2%), if any, genetic admixture has occurred with the black community living in the same area. Correspondence analysis was used to study the genetic relationships between the Cayapa and other linguistically defined Amerind populations and between the Amerinds and the other two native American groups, the Na-Dene and Eskimo-Aleut. The results of this analysis, obtained on the basis of some erythrocyte and serum markers and some blood group systems, show (1) the close affinity between the Cayapa and other South American populations, (2) the absence in the Amerind group of a clear-cut correspondence between linguistic classification and genetic relatedness, and (3) the evident distinctiveness of the Amerinds from other native American people.

The Cayapa Indians of Ecuador: a population study of seven protein genetic polymorphisms

The Cayapa Indians are a population of 3600 individuals living in Ecuador, along the Cayapas River and its tributaries. They are thought to have migrated from the Andes, north of Quito, and settled in the Cayapas area five centuries ago as a consequence of Inca expansion and of the Spanish conquest. In order to study the genetic structure of the Cayapa and their relationships with other native American peoples, and to enquire on the possibility of admixture from nearby Black communities, we have investigated a sample of 139 individuals for seven plasma genetic markers (F13A, F13B, ORM1, AHSG, C6, C7 and APOC2) by isoelectric focusing and immunoblotting. The following gene frequencies have been found: F13A*1 = 0.824, F13A*2 = 0.176; F13B*1 = 0.126, F13B*3 = 0.874; ORM1*1 = 0.554, ORM1*2 = 0.446; AHSG*1 = 0.275, AHSG*2 = 0.725; C6*A = 0.131, C6*B = 0.814, C6*A21 = 0.055; C7*1 = 1.000; APOC2*1 = 1.000. The findings confirm, whenever the comparison was possible, quite a good resemblance of the Cayapa with other Native American populations.

Survey of seven plasma protein polymorphisms in the Amhara and Oromo populations of Ethiopia

The Ethiopian population is very difficult to specify due to a very high degree of intermixing among different peoples. The two groups of the present study, the Amhara and Oromo, constitute 38% and 35% of the population, respectively. In order to investigate the genetic composition of the Amhara and Oromo, genetic polymorphisms of seven plasma proteins (F13A, F13B, ORM1, AHSG, C6, C7, and APOC2), already identified as useful anthropological markers, were studied. No statistically relevant differences were found between the two groups for all of the systems examined. ORM1 and F13A showed frequencies in the range observed in other populations of Caucasoid and Negroid origin. F13B, AHSG, and C6 displayed gene frequencies and a number of variant alleles that seem particular to these two groups. No variation was observed for C7 and APOC2. Correspondence and distance analyses were used to interpret and compare the gene frequencies of the Amhara and Oromo with those of other related populations. These methods locate Ethiopians in an intermediate position between African Blacks and a group of Caucasoid populations, confirming cultural and historical data. © 1994 Wiley-Liss, Inc.

Marriage distances among the Afroamericans of Bluefields, Nicaragua

In a sample of 311 couples from the Afroamerican community of Bluefields, Eastern Nicaragua, the distribution of matrimonial distance shows a deviation from the leptokurtic rule. This results from assortative mating among the population.

Investigations on the variability of four genetic serum protein markers (HP; TF, GC and PI subtypes) in Italy

14 population samples from various Italian regions with a total of 2.577 unrelated male and female individuals were typed for four polymorphic serum protein polymorphisms: HP, and TF, GC and PI subtypes. The regional distribution of the allele frequencies of these four polymorphisms shows a considerable heterogeneity, which is for the most part statistically significant, thus indicating an obvious genetic variability of the population of the Italian Peninsula.

Genetic structure of the population of Sicily

Genetic heterogeneity within Sicily was investigated on the basis of ACP1, ADA, ESD, GLO1, PGD, PGM1, PGM2, SODA, ABO, and MN gene frequencies, and compared to those of other regions of Italy for which these same loci have been examined. Correspondence analysis revealed no differences within the island, at least at the provincial level, but showed genetic differentiation among Italian regions, distinctly clustering northern, central, and southern populations, respectively. These data indicate a close relationship between Sicily and southern Italy. In addition, the contribution of Middle Eastern populations to the gene pool of Sicily was evident.

Gm and Km allotypes in four Sardinian population samples

Serum samples of 683 unrelated male and female individuals of four Sardinian population samples (Sassari, Nuoro, Oristano and Cagliari) were typed for G 1 m (1,2,3,17), G 3 m (5,6,10,11,13,14,15,16,21,26), and Km (1). Phenotype, haplotype (Gm), and allele frequencies (Km), respectively, show a remarkable variability between these four population samples. Comparisons with other Italian populations reveal the considerable genetic difference of the Sardinians, which is in particular caused by the presence of the haplotype Gm1,3;5,10,11,13,14,26 in them. This haplotype is quite uncommon in Europeans and may reflect gene flow from Eastern populations (Phoenicians?) who came to this island in ancient-history times.

ESD, GLO1, PGD, PGM1 and PGM2 gene frequencies in the Salerno Province (Italy)

Esterase D (ESD), glyoxalase 1 (GLO1), phosphogluconate dehydrogenase (PGD) and phosphoglucomutase 1 and 2 (PGM1 and PGM2) systems have been studied in the Salerno province (Campania, Southern Italy). The mean weighted frequencies for the Campania region were calculated. These frequencies show a general similarity to those reported for the other Italian regions.

Size and shape of human cranial sutures--a new scoring method

A method for the differentiation of sutural patterns of the human cranial vault is introduced. Three criteria of differentiation are considered, one for size and two for shape: 1) maximal shape extension; 2) basic configuration; 3) secondary protrusion. The method is illustrated here for the coronal and lambdoid sutures of 70 recent Italian skulls (35 adult males and 35 adult females). Differences between coronal and lambdoid sutural size and shape can be detected analytically; for example, the coronal suture commonly shows lesser degrees of shape extension, a simpler basic configuration, and an absence of secondary protrusion. Heterogeneity within each suture, as well as a relationship among corresponding sections and between the three criteria adopted, have been also observed; symmetry predominates for both the sutures, and sexual differences are slight.

Red-cell enzyme polymorphisms in the Reggio Calabria province (Italy)

Acid phosphatase (ACP1), adenosine deaminase (ADA), esterase D (ESD), glyoxalase 1 (GLO1), phosphogluconate dehydrogenase (PGD) and phosphoglucomutase 1 and 2 (PGM1 and PGM2) polymorphisms have been studied in the Reggio Calabria province (Southern Italy). The ACP1*A allele and ADA, GLO1, PGD and PGM1 systems have frequencies similar to those reported for Sicily and Southern Italy.

Migration pattern and genetic marker distribution of the Afro-American population of Bluefields, Nicaragua

On a sample of the population of mixed African ancestry living in Bluefields, Nicaragua, the pattern of migration and the distribution of red cell and serum genetic markers have been studied. It is concluded that, in spite of a considerable level of internal and external migration, a distinctive genetic structure is maintained by the population. Moreover, a strongly negative assortative mating can be observed between people inhabiting the western and eastern areas of Nicaragua. It is estimated that most, if not all, of the genetic pool of the population is accounted for by a process of admixture between African and Indian peoples.

Red cell polymorphisms in Sardinia

Acid phosphatase (ACP1), esterase D (ESD) and phosphoglucomutase 1 (PGM1) polymorphisms have been studied in Sardinia and the following gene frequencies have been found: ACP1*A = 0.235, ACP1*B = 0.684 and ACP1*C = 0.081; ESD*2 = 0.118 and PGM1*2 = 0.233. These findings confirm the genetic uniqueness of Sardinians compared to the other Italian and European populations.

Genetic study of the haptoglobin polymorphism in Italy: I. Bari and Genoa provinces

A random sample of 686 unrelated subjects from Bari (Southern Italy) and Genoa (Northern Italy) provinces was studied for HP polymorphism. The correlation between the HP*1 frequencies and geographical coordinates was studied for the populations of Italy, Europe, Middle East and Mediterranean basin. The results reveal the existence of a gradient of declining HP*1 frequencies from north-west to south-east across Europe and the Middle East.

The Alu I-induced bands in metaphase chromosomes of orangutan (Pongo pygmaeus). Implications for the distribution pattern of highly repetitive DNA sequences

Restriction endonucleases have been recently proved to be active on fixed chromosomes, thus they are useful in chromatin structure studies. Within this class of enzymes, Alu I is able to detect the presence and localization of highly repetitive DNA sequences in human and in other mammalian and dipteran species. In this paper the pattern obtained on fixed metaphase chromosomes of orangutan (Pongo pygmaeus) by Alu I digestion and Giemsa staining is shown. The results are discussed in the light of the distribution, in this species, of the I-IV human satellite DNAs. It is also suggested that in Pongo some highly repetitive sequences, different from the major human satellites, are present.

Variations of supraorbital bony structures in Sienese skulls

Various non-metrical traits were examined in the supraorbital region in a series of skulls of recorded sex (147 males, 130 females), age (18-80 years) and provenance (Siena and surroundings), using a standard method of categorization and notation introduced by two of the authors in 1983. The results are discussed from a topographic-anatomical point of view in relation to trait variation and with respect to the usefulness of the method applied for population studies.

New cytogenetic techniques in the study of primate genome evolution

Fixed metaphase chromosomes of different species and genera of Primates (five species of Macaca genus and Callithrix jacchus) have been studied after Alu I restriction enzyme digestion and DA-DAPI counterstaining, in the attempt to determine some qualitative characteristics of their DNAs and specifically of the DNA localized in the heterochromatic components of the karyotypes. The results have been discussed in the light of those already published on humans, confirming the potentiality of this approach in the study of the phyloevolutive relationships in Primates.

On the variability of Gc subtypes in Italy

909 individuals from different places of Italy were analyzed for the distribution of Gc subtypes. The observed heterogeneity in the distribution of the allele frequencies was found to be statistically significant. Comparing our results with those reported by other authors it is seen that within Italy a considerable regional variation in the frequencies of the Gc subtype alleles is present. However, there are no indications for any particular distribution patterns or gradients. In one of our samples (Bari district), one case of Gc 1S-1C3 was found.

Variations in form of the hypoglossal canal

Variation in the nature and extent of division of the hypoglossal canal can be classified by a simple scoring scheme. Applied to three series of crania of differing provenance, the results indicate a continuity in expression of the trait rather than the dichotomous character utilized in previous studies. The similarity in results in these three populations, of widely differing environment, suggests fairly strict canalization of development.

A morphotypological analysis of an Italian population: association with obesity

The morphotypological method of Brian (1960) was applied to the data collected in Aosta (N. Italy) during an investigation on human obesity. The data consist of anthropometric measurements on members of families ascertained by the presence of obesity in the children and therefore the frequency of obesity is much higher than in the general population. One of the morphotypes was found only among the obese and two others were much more common among the obese than among the non-obese. More than 80% of the obese (vs. 10% of the non-obese) belonged to these three classes. There was a positive parent-offspring association for two of the components of the morphotype (morphy and somy).

Variations in the method of the division of the hypoglossal canal in Sienese skulls of known age and sex

In 300 Sienese skulls of known age and sex (146 male and 154 female) 6 modes of expression of bipartition of the hypoglossal canal were studied on the basis of a new scheme of notation that takes into account gradually increasing intensity. The analysis of data, including also the traditional method of notation confirms the criticisms expressed by various authors on the loss of information when the variability of this trait is neglected, especially with reference to age-dependent changes (hyperostotic effects).

Characterization of a rare allele of the phosphoglucomutase locus 1 (PGM81) in an Italian family by isoelectric focusing

A rare phenotype at the phosphoglucomutase locus 1 with an electrophoretic mobility similar to that of PGM1 8-1 was found in an Italian family. The study of this variant was performed by isoelectric focusing on polyacrylamide gel. Also the isoelectric point of the PGM81 gene product was determined.