摘要:

Genetic data organized in the form of genealogies can provide much information regarding the history and genetic structure of human populations. A large proportion of the population of Latin America is organized in small rural semi-isolated communities, with little immigration, and until the last 50–100 years, little emigration. These communities have a strong sense of their genealogical history, and this ‘genealogical conscience’ is a frequent leitmotif in modern Latin-American literature. In this communication, we compare the characteristics of fictitious genealogies described in two masterpieces of Latin-American literature, Garcia Márquez’ Cien Años de Soledad (A Hundred Years of Solitude) and Verissimo’s·Tempo e·Vento (Time and the Wind) with one existing well-studied population in Argentina, Aicuña All three populations exhibit a number of common characteristics, such as histories of long periods of civil war, and large pedigrees with complex paths of inheritance resulting in complex patterns of inbreeding. Genetic themes common to all three are: (1) the use of genealogical records to substantiate the property of the land or the political power of a kinship; (2) the genealogical registry of biological descendants, independent of their legal or marital status in the clan; (3) the existence of pedigrees of the aristocratic branches in the same kindreds, which illustrate the legal principle of primogeniture; (4) the value of last names as indicators of kinships and the extent of genetic isolation, and (5) the awareness of the deleterious consequences of

ISSN:0001-5652    

DOI:10.1159/000154361

出版商:S. Karger AG    

年代:1996

数据来源: Karger

摘要:

The aim of this study was to explore the association between socio-demographic factors and consanguineous marriages in the United Arab Emirates (UAE). This was a cross-sectional population-based study conducted in the cities of Al Ain and Dubai between October 1994 and March 1995. A multi-stage sampling design was used and a representative total sample of 2,200 UAE females aged 15 years and above were included in this study. Data on 2,033 (85.8%) UAE national families who consented to participate in the study were obtained. The rate of consanguineous marriages in the sample was found to be 50.5% with 95% estimated population confidence limits 49.2–51.8%. The socio-demographic factors considered were: husband’s age, wife’s age, husband’s and wife’s educational levels, husband’s occupation, wife’s occupation, housing conditions, husband’s parental kinship, wife’s parental kinship, and kinship between the spouses. Consanguinity is more common among women with educated husbands (secondary or university/high) than among women with less educated husbands. The results indicate that the frequency of consanguineous marriages significantly increases when the husband’s educational level is higher (p = 0.003). The distribution of relationship between spouses over the two generations of the study group and their parents is presented. The incidence of consanguineous marriages among the parents is 53% and 62% for the women and their husbands, respectively, and the overall incidence is 57%. The parallel patrilateral marriage is obviously the favoured practice when considering the parent’s kinship distributions. The results of step-wise multiple logistic regression analysis for the occurrence of consanguineous marriages show that the husband’s education and husband’s parents’ consanguinity status only are signifi

ISSN:0001-5652    

DOI:10.1159/000154362

出版商:S. Karger AG    

年代:1996

数据来源: Karger

摘要:

In this study we explore whether a phenocopy frequency (defined as a ‘penetrance’ for nondisease genotypes) can approximate or model genetic heterogeneity in a single-locus analysis. We simulated two types of heterogeneity situations: ‘sporadic models’, where there are two forms of a disease, one genetic and linked to a marker and the other purely random, and ‘genetic heterogeneity models’, where the disease is caused by either of two different loci, one linked to the marker and the other unlinked. We analyzed simulated data sets for linkage, assuming a single-locus analysis with varying phenocopy frequency, in analogy with earlier work on epistatic two-locus models. We found that in the presence of purely random sporadics, there was a difference between assuming any nonzero phenocopy frequency and a zero frequency, but that the actual value of the assumed phenocopy frequency had little effect on the maximum lod score. In contrast, when both forms of disease are genetic, and are generated under similar genetic parameters, assuming a positive phenocopy frequency will not, in general, compensate for the presence of the unlinked form. However, when the modes of inheritance of the two forms differ, the assumption of a nonzero phenocopy frequency does have an effect, either to increase or decrease the maximum lod score, depending on the modes of inheritance of the two disease forms. We conclude with practical recommendations for investigators, based on th

ISSN:0001-5652    

DOI:10.1159/000154363

出版商:S. Karger AG    

年代:1996

数据来源: Karger

摘要:

The allele frequencies of six VNTRs (D1S80, D4S43, ApoB 3’ VNTR, von Willebrand factor VNTR-I, DXS52 and DYS19) in 123 Amerindians from five tribes (Arara, Wayana-Apalai, Wayampi, Yanomama and Kayapo) were compared with three other Brazilian populations: Whites, Blacks, and individuals of Japanese extraction. The data clearly distinguished the four populations, and measurements of diversity show a decreasing average heterozygosity from Blacks to Whites, Japanese, and Indians. Seven novel alleles were observed; amongst them, two small DYS19 alleles and a large D4S43 allele occurred only in Indians, and may be useful genetic markers for this population. Other prominent features of the Amerindians were: (1) high frequency of ApoB allele 46; (2) absence of a shorter variant of D4S43 allele 1; (3) high frequency, limited to one tribe, of allele 12 of the von Willebrand VNTR. The study also demonstrated a heterogeneity of the Indian tribes, due to both different allele frequencies and the presence or absence of specific alleles. Gst was 0.106 for the five Indian populations, and 0.065 for Whites, Blacks and Japanese. HS and HT demonstrated that 11 % of the total diversity among Amerindians is caused by interpopulational variability, as compared with 7% for the other three racial groups. In contrast, diversity within each tribe is usually low, as demonstrated by a low average number of alleles per locus. These findings indicate that the study of a small number of tribes may not be representative of the variability of Amerindians, even if a large number of individuals are studied. To capture the whole range of genetic variability of Amerindians, it is necessary to study a large number of populations. The limited genetic diversity thus far observed for Amerindians seems to reflect both a genuine decrease of diversity and a bias caused by the study of limited numbers of tribe

ISSN:0001-5652    

DOI:10.1159/000154364

出版商:S. Karger AG    

年代:1996

数据来源: Karger

摘要:

The relationship between three p53 polymorphisms (BstUIand MsplRFLPs in exon 4 and intron 6, respectively, and a 16-bp duplication in intron 3) in placental tissue and placental weight was examined in an attempt to elucidate the effect of p53 alleles on non-malignant growth. Placental tissue is expressing the fetal genotype. Using the quantitative trait loci approach, allelic frequencies of the three p53 polymorphisms and ten alleles at other loci (ABO, PLAP, GC and ACPI) were compared for the high (≧700 g) and low (<400 g) tails (±1.4 SD) of the placental weight distribution in a Swedish sample of newborns. Significant associations were found in the three p53 polymorphisms examined but not for the other loci, suggesting that non-malignant cell growth may be influenced by polymorphic p53 variants. High placental weight was associated with increased frequencies of the 16-bp duplication (A2 allele), the codon 72 BstUlAl (pro) allele and the MsplAl allele. These three alleles were in strong linkage disequilibria, and high placental weight was therefore associated with the 2-1-1 haplotype. The fact that the strongest associations were found with intronic markers suggests linkage disequilibrium with growth-promoting sites at the p53 molecule as the most likely mechanism, although a direct functional involvement of the codon 72 pro/arg substitution in normal cell growth cannot be exclud

ISSN:0001-5652    

DOI:10.1159/000154365

出版商:S. Karger AG    

年代:1996

数据来源: Karger

摘要:

Meprins are membrane-bound oligomeric metalloendopeptidases belonging to the astacin protein family. The meprin isolated from human small intestinal mucosa was originally known as N-benzoyl-L-tyrosyl-p-aminobenzoic acid (PABA peptide) hydrolase (PPH). Here we describe the first genetic marker for the human MEP1A gene encoding the α subunit of this enzyme. The polymorphism changes codon 176 of the mature α chain of PPH from CAA to CAG. Using the polymerase chain reaction, this variation is easily detectable as a Hhal restriction fragment length polymorphism. The two alleles are both common, probably in all major race

ISSN:0001-5652    

DOI:10.1159/000154366

出版商:S. Karger AG    

年代:1996

数据来源: Karger