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Linkage of biopsy, cancer, and population records aimed at the estimation of family risks in neoplasia: a pilot study
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LINKAGE OF BIOPSY, CANCER, AND POPULATION RECORDS AIMED AT THE ESTIMATION OF FAMILY RISKS IN NEOPLASIA - A PILOT-STUDY
Author(s): BARRAI, I (BARRAI, I); NENCI, I (NENCI, I); GUIDI, E (GUIDI, E); DELLACQUA, G (DELLACQUA, G); FORMICA, G (FORMICA, G); BARBUJANI, G (BARBUJANI, G); MARZOLA, A (MARZOLA, A); MARANI, G (MARANI, G); BARALE, R (BARALE, R); BERETTA, M (BERETTA, M)
Source: JOURNAL OF EPIDEMIOLOGY AND COMMUNITY HEALTH Volume: 45 Issue: 2 Pages: 107-111 DOI: 10.1136/jech.45.2.107 Published: JUN 1991
Times Cited: 1 (from Web of Science)
Cited References: 15 [ view related records ] Citation Map
Abstract: Study objective-The aim was to link individual demographic and medical records into sibships to obtain the sibling distribution of biopsies and cancers, and thereby calculate heritability and recurrence risks in families, thus aiding early diagnosis and prevention of cancers.
Design-The 157 823 individual records of the inhabitants of the town of Ferrara in Italy were automatically linked into 106 821 sibships. A 10% sample (10 842 sibships) was then extracted from the distribution of sibships and tabulated, for linkage to medical records.
Patients-The biopsy records at the Institute of Pathological Anatomy of the University of Ferrara were manually linked to cancer records and then to sibships. It was possible to construct the distribution of 2062 biopsies and of 829 cancers in sibships.
Results-From the distribution of biopsies and tumours in sibships, it was possible to estimate the incidence of tumours in the population (0.052) and in siblings of affected (0.083), and to apply to such distributions current methods for the estimate of heritability (h2 = 0.246) and of recurrence risks of tumours in sibships, age independent.
Conclusions-The study shows that the procedure resulting in the estimation of incidences and recurrence risks for tumours could be completely automated, and extended to whole populations and homogeneous subgroups in post industrial cultures
Neolithic demic diffusion
No full textIn 1978, Paolo Menozzi, Alberto Piazza, and Luca Cavalli-Sforza paved the ground for a new multidisciplinary approach to the study of human prehistory, interpreting genetic evidence in the light of archaeological information. By producing synthetic maps of allele frequencies and summarizing them by principal component analysis (PCA), they identified an association between patterns in genetic diversity across Europe and in the Neolithic archaeological record showing the earliest documented dates of farming societies. Based on this observation, they proposed a model of demic diffusion from the Near East. They argued that the observed patterns were the result of population growth due to increased food availability in early farming communities, westward dispersal of early farmers, and relative isolation between dispersing farmers and local hunter-gatherers. These results played a major role in our understanding of the Neolithic transition, but were also criticized on methodological grounds. For instance, it has become increasingly clear that the interpretation of PCA plots is less straightforward than originally thought, and correlations should be corroborated by explicit comparison of alternative demographic models. Despite these valid criticisms, genetic and genomic studies, including those involving ancient DNA, have largely confirmed the crucial role of the Neolithic transition as a process of demographic change in European prehistory, with some qualifications. Today, there is still much to be learned about the details of that complex history, but many researchers regard the European population structure as largely reflecting the genetic consequences of three major migrations: from Africa in Upper Paleolithic times, from the Near East at the beginning of the Neolithic, and from the eastern steppes in the Bronze Age. This deep structure has not been erased, despite many additional processes involving historical migrations, isolation (i.e., drift) and local gene flow, and has been recognized thanks to the pioneering work of Menozzi, Piazza and Cavalli-Sforza
GEOGRAPHICAL STRUCTURING IN THE MTDNA OF ITALIANS
No full textGeographical patterns of mtDNA variation were studied in 12 Italian samples (1072 individuals) by two different spatial autocorrelation methods. Separate analyses of the frequencies of 12 restriction morphs show North-South dines, differences between Sardinia and the mainland populations, and the effects of isolation by distance. A recently developed autocorrelation statistic summarizing molecular similarity at all sites (AIDA; autocorrelation index for DNA analysis) confirms the presence of a clinal pattern; differences between random pairs of haplotypes tend to increase with their geographical distance. The partition of gene diversity, however, reveals that most variability occurs within populations, whereas differences between populations are minor (G(ST) = 0.057). When the data from the 12 samples are pooled, two descriptors of genetic variability (number of polymorphic sites and average sequence difference between pairs of individuals) do not behave as expected under neutrality, The presence of clinal patterns, Tajima's tests, and a simulation experiment agree in suggesting that population sizes in creased rapidly in Italy and Sicily but not necessarily so in Sardinia, The distribution of pairwise sequence differences in the Italian peninsula (excluding Sardinia) permits a tentative location of the demographic increase between 8000 and 20,500 years ago. These dates are consistent with archaeological estimates of two distinct;expansion processes, occurring, respectively, in the Neolithic and after the last glacial maximum in the Paleolithic, Conversely, there is no genetic evidence that such processes have had a major impact on the Sardinian population
Barriers to gene flow estimated by surname distribution in Italy
No full textSurname distributions were studied in order to reconstruct human migration patterns. Zones of sharp change in surname frequencies--presumably barriers to gene flow--were detected by the statistical technique of wombling (Barbujani et al. 1989), using data from consanguineous marriages (1910-64) collected from 280 Italian dioceses which we grouped into 80 provinces. The 28 observed surname boundaries were compared with physical (geographical) and cultural (linguistic) barriers, and with boundaries detected from distributions of 57 alleles in the same territorial subdivisions. Genetic and surname boundaries had similar locations, as expected given the analogy in the inheritance mechanism of genes and surnames. Physical barriers seemed to be the main cause of gene flow reduction. However, cultural factors alone (e.g. linguistic ones) also determined barriers that delimited areas of homogeneous gene (and surname) frequency probably due to increased endogamy. The observed similarity between spatial patterns of surnames, genes and languages supports the hypothesis of the co-evolution of genetic and linguistic variation
Duchenne muscular dystrophy - Frequency of sporadic cases
No full textA segregation analysis on 135 Duchenne families from Venetia (Italy) suggests that the proportion of sporadic cases might be less than expected. Support for this view is also given by an analysis of a pooled sample including 284 additional sibships from comparable studies published previously. Several hypotheses were tested: the maximum likelihood was obtained for a segregation frequency p=0.46 and for a proportion of sporadic cases x=0.227±0.048. © 1984 Springer-Verlag
Geographical patterns of gene frequencies in Italian populations of Ornithogalum montanum (Liliaceae)
No full textGeographic variation was studied at 15 electrophoretic loci (40 alleles) in Italian populations of Ornithogalum montanum Cyr. ex Ten. (Liliaceae). Homogeneity of allele frequencies was assessed by G tests; gene-frequency patterns were described by spatial autocorrelation statistics; matrices of genetic and environmental distance were compared through a series of Mantel's tests, and the zones of highest overall gene-frequency change per unit distance (steep multi-locus clines, or genetic boundaries) were identified. Nineteen allele frequencies appear heterogeneously distributed, but only 3 of them show significant spatial structure. Only 2 allele frequencies are correlated with 1 environmental parameter. Large genetic differences are observed between spatially close populations. These findings support a model of differentiation in which the genetic relationships between isolates do not depend on their spatial distances, but reflect mainly population subdivision and restricted gene flow. © 1991, Cambridge University Press. All rights reserved
Diversity of some gene frequencies in European and Asian populations. V. Steep multilocus clines
No full textRegions of abrupt genetic change, which result from either rapid spatial change of selective pressures or limited admixture, were investigated in Europe and Asia on the basis of eight red cell markers typed in 960 samples. Two methods were employed, one based on genetic distances and one on evaluation of the first derivative of the surfaces representing allele-frequency variation. Genetic divergence tends to be maximal between populations that are separated by physical factors (mountain ranges and seas) but also separated by cultural barriers (different language affiliation). This suggests that mating isolation, rather than adaptive response to environmental change, accounts for spatially abrupt genetic change at the loci studied and that cultural differences associated with language contribute to isolating populations. Although selection may have determined two wide allele-frequency gradients, the genetic structure of European and Asian populations seems primarily to reflect isolation by distance when investigated on a small scale and migration patterns (or absence of migration) when investigated on a larger scale
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