Evolution of consanguinity in the Bishopric of Lugo (Spain) from 1900 to 1979

BACKGROUND: The levels of consanguinity in human populations are known to be influenced by demographic and geographical factors, and by socio-cultural customs that govern spouse choice. Within the general model applicable to the populations of Western Europe, Galicia (north-west Spain) is a region that is especially interesting, due to its geographical and historical peculiarities that could have conditioned its behaviour pattern with respect to consanguinity. PRIMARY OBJECTIVE: The object of this paper is to analyse the evolution of the consanguinity structure levels in the rural population of the Bishopric of Lugo (Galicia) during the period 1900-1979. SUBJECTS AND METHODS: The study covers a total of 752 parishes included in 52 municipalities of the rural area of the Bishopric of Lugo. Of a total of 117,583 marriages in the period studied, 6701 were between biologically related individuals up to the level of second cousins. The percentage of the different types of consanguineous marriages, the consanguinity rates, and the average coefficient of inbreeding of the population was calculated. Also, for the analysis of the temporal variation of consanguinity, version 3.01 of Jandel Scientific's Table Curve program was used. MAIN OUTCOMES AND RESULTS: The consanguinity rate for the whole of the period is 5.70% and the average coefficient of inbreeding is 2.2477 x 10(-3), values which fall within the observed range for Spanish populations. As for the consanguinity structure, the most frequent types of consanguineous marriages are between second cousins (2.65% of all marriages), but the high proportion of marriages between uncles/nieces or aunts/nephews (0.16%) and first cousins (2.12%) with regard to the total number of marriages should be emphasized. The average value of the M22/M33 ratio is 0.80, and throughout the study period it was above the 0.25 expected in conditions of panmixia. Regarding the evolution of the average coefficient of inbreeding, its annual values fit a polynomial regression curve with one ascending and one descending branch and an inflection point in the year 1919. CONCLUSIONS: As in other rural areas of Galicia, the structure of consanguinity in the Bishopric of Lugo is characterized by the high proportion of marriages between uncles/nieces or aunts/nephews and first cousins, a phenomenon which appears to be generalized in the rural populations of northern Spain. It is suggested that the high proportion of uncle/niece marriages that have been found in the population studied are very probably due to the important migratory phenomenon which took place in this region at the end of the 19th century and in the first third of the 20th century.     

Consanguinity in the Bishopric of Ourense (Galicia,Spain) from 1900 to 1979

Background : Knowledge of the levels of inbreeding in the human population is interesting because it is one of the characteristics that conditions its genetic structure and has important genetic-medical repercussions in the descendants of marriages between close relatives. Galicia (north-west Spain) is a region with very special geographic, historic and social characteristics that makes it particularly interesting for consanguinity studies. Primary objective : The object of this investigation is the study of the levels of inbreeding and the structure of consanguinity in rural area of the Dioceses of Ourense (Galicia) during the period 1900-1979. Subjects and methods : In the study, data corresponding to 437 parishes, integrated in 80 municipalities of the rural area of the Dioceses of Ourense were analysed. In the period studied, of a total of 110 128 marriages, 9010 took place between biologically related individuals up to the level of second cousins. The rate of consanguinity and the average coefficient of inbreeding of the population, as well as the percentage of the different types of consanguineous marriages, were calculated. Main outcomes and results : The rate of consanguinity for the period 1900-1979 is 8.18% and the average coefficient of inbreeding is 3.0662 &#50 10 &#109 3. The most frequent type of consanguineous marriage is between second cousins (4.00% of all marriages). There is a notably high frequency of marriages of multiple relationships (0.52%) and the frequency of uncle-niece or aunt-nephew marriages is 0.16%. The average value of the M22/M33 ratio is 0.66 and during the 80 years studied, with regard to the temporal variation of the average coefficient of inbreeding, the annual values followed a polynomial curve with an inflection point in 1921. Conclusions : The highest values of consanguinity detected in Galicia, for the same period, were registered in the Dioceses of Ourense and the high rate of uncle-niece or aunt-nephew marriages habitual in this region was confirmed. The latter is explained by the important incidence in the Galician population of the migration to America at the end of the 19th and beginning of the 20th century. However, when the relative frequency of this type of marriage with respect to the total number of consanguineous marriages is calculated, it has relatively low values due to the high proportion of marriages between second cousins and marriages of multiple relationships, the highest in Galicia for an equal period of time. The rate of marriages between first cousins is also the highest in Galicia, confirming a phenomenon that appears to be common in the rural areas of the northern area of the Iberian Peninsula.     

Consanguinity in the Bishopric of Ourense (Galicia,Spain) from 1900 to 1979

BACKGROUND: Knowledge of the levels of inbreeding in the human population is interesting because it is one of the characteristics that conditions its genetic structure and has important genetic-medical repercussions in the descendants of marriages between close relatives. Galicia (north-west Spain) is a region with very special geographic, historic and social characteristics that makes it particularly interesting for consanguinity studies. PRIMARY OBJECTIVE: The object of this investigation is the study of the levels of inbreeding and the structure of consanguinity in rural area of the Dioceses of Ourense (Galicia) during the period 1900-1979. SUBJECTS AND METHODS: In the study, data corresponding to 437 parishes, integrated in 80 municipalities of the rural area of the Dioceses of Ourense were analysed. In the period studied, of a total of 110 128 marriages, 9010 took place between biologically related individuals up to the level of second cousins. The rate of consanguinity and the average coefficient of inbreeding of the population, as well as the percentage of the different types of consanguineous marriages, were calculated. MAIN OUTCOMES AND RESULTS: The rate of consanguinity for the period 1900-1979 is 8.18% and the average coefficient of inbreeding is 3.0662 x 10(-3). The most frequent type of consanguineous marriage is between second cousins (4.00% of all marriages). There is a notably high frequency of marriages of multiple relationships (0.52%) and the frequency of uncle-niece or aunt-nephew marriages is 0.16%. The average value of the M22/M33 ratio is 0.66 and during the 80 years studied, with regard to the temporal variation of the average coefficient of inbreeding, the annual values followed a polynomial curve with an inflection point in 1921. CONCLUSIONS: The highest values of consanguinity detected in Galicia, for the same period, were registered in the Dioceses of Ourense and the high rate of uncle-niece or aunt-nephew marriages habitual in this region was confirmed. The latter is explained by the important incidence in the Galician population of the migration to America at the end of the 19th and beginning of the 20th century. However, when the relative frequency of this type of marriage with respect to the total number of consanguineous marriages is calculated, it has relatively low values due to the high proportion of marriages between second cousins and marriages of multiple relationships, the highest in Galicia for an equal period of time. The rate of marriages between first cousins is also the highest in Galicia, confirming a phenomenon that appears to be common in the rural areas of the northern area of the Iberian Peninsula.     

Serotypes, virulence genes, and intimin types of Shiga toxin (verotoxin)-producing Escherichia coli isolates from human patients: prevalence in Lugo, Spain, from 1992 through 1999

We have analyzed the prevalence of Shiga toxin-producing Escherichia coli (STEC) in stool specimens of patients with diarrhea or other gastrointestinal alterations from the Xeral-Calde Hospital of Lugo City (Spain). STEC strains were detected in 126 (2.5%) of 5,054 cases investigated, with a progressive increase in the incidence from 0% in 1992 to 4.4% in 1999. STEC O157:H7 was isolated in 24 cases (0.5%), whereas non-O157 STEC strains were isolated from 87 patients (1.7%). STEC strains were (after Salmonella and Campylobacter strains) the third most frequently recovered enteropathogenic bacteria. A total of 126 human STEC isolates were characterized in this study. PCR showed that 43 (34%) isolates carried stx(1) genes, 45 (36%) possessed stx(2) genes and 38 (30%) carried both stx(1) and stx(2). A total of 88 (70%) isolates carried an ehxA enterohemolysin gene, and 70 (56%) isolates possessed an eae intimin gene (27 isolates with type gamma1, 20 with type beta1, 8 with type zeta, 5 with type gamma2, and 3 with type epsilon). STEC isolates belonged to 41 O serogroups and 66 O:H serotypes, including 21 serotypes associated with hemolytic uremic syndrome and 30 new serotypes not previously reported among human STEC strains in other studies. Although the 126 STEC isolates belonged to 81 different seropathotypes (associations between serotypes and virulence genes), only four accounted for 31% of isolates. Seropathotype O157:H7 stx(1) stx(2) eae-gamma1 ehxA was the most common (13 isolates) followed by O157:H7 stx(2) eae-gamma1 ehxA (11 isolates), O26:H11 stx(1) eae-beta1 ehxA (11 isolates), and O111:H- stx(1) stx(2) eae-gamma2 ehxA (4 isolates). Our results suggest that STEC strains are a significant cause of human infections in Spain and confirm that in continental Europe, infections caused by STEC non-O157 strains are more common than those caused by O157:H7 isolates. The high prevalence of STEC strains (both O157:H7 and non-O157 strains) in human patients, and their association with serious complications, strongly supports the utilization of protocols for detection of all serotypes of STEC in Spanish clinical microbiology laboratories.