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PubMed1991

Frequency of first-cousin marriages from civil marriage certificates in Argentina.

In Argentina information concerning relatedness of mates, especially first cousins, was introduced into the legal marriage certificate, record, and statistical report in 1968. The 1980-1981 biennial data, including 212,320 legal marriage reports, were analyzed for all of Argentina, subdivided into 22 states and 494 counties. The registered 0.373% of first-cousin marriages allows an estimate of consanguineous marriages of 0.629% and a mean inbreeding coefficient of alpha = 0.00031. This estimate lies between the observed alpha = 0.00011 from hospital births and alpha = 0.00052 from Roman Catholic Church dispensations. These differences are not large, and they may be due to sampling variations, indicating a low rate of inbreeding in Argentina. The frequency of first-cousin marriages in the 22 Argentine states is heterogenous, and 9 counties, representing 5 different regions, were identified as having a high rate of first-cousin marriage. Three of these were previously known as genetic isolates. A second series of data, including all 32,690 legal marriages registered in the state of Buenos Aires during the first half of 1984, showed a frequency of first-cousin marriages of 0.677%. First-cousin mates, compared with non-first-cousin mates, had a higher frequency of both mates being born in the same state of Buenos Aires and similar frequency distributions for age at marriage, single previous marriage status, level of education, and rate of unemployment. It is concluded that legal marriage data on consanguinity is reliable, inexpensive, universal, and enduring. The last two characteristics make them suitable for the survey of geographic clusters and time trends.

Argentina↗
PubMed1990

[Genetic epidemiologic study of hydrocephalus].

This paper described the epidemiological pattern and genetic features of congenital hydrocephalus. 77 214 births (live and still) were monitored, among whom 84 were hydrocephalus, incidence of 1.09%. The results suggested that the maternal occupation, age, number, of gravidity and educational level may be major contributors to the incidence of hydrocephalus. The incidence of hydrocephalus was significantly different between urban and rural areas, and its prevalence in the offsprings of parental consanguinity was 9.8%, being 9 times higher than those of non-consanguineous marriages (P less than 0.001). The incidence of hydrocephalus in the first degree relatives of the patient was 12.82%, being 10.76 times higher than that of the general population. The herebitability of the first degree relative was 49.6%.

China↗
PubMed1989

[The genes of the Pascuense population].

An analysis of the interaction of evolutionary factors such as migration, mutation, selection random drift, and consanguinity upon the genome of Easter islanders is attempted. As many primitive populations, the Easter islanders genome has at least 2/3 of genetic loci in an isogenic state. The HLA system is reduced; other polymorphisms present high genic frequencies differentiating Easter islanders from other Andean and european populations. They are more similar to polynesians, with whom they share language and culture. Migration has been the main factor affecting the Easter islanders genome, leading to a ten fold increase in population and a 60% caucasian admixture. A linkage disequilibrium of the HLA9, w10 haplotype exists. In XIX century generations consanguinity was very low (alpha coefficient 7 x 10(-5) which may be explained by the exogamic tradition of the population; this acted as a factor opposed to random drift. A recent decrease in infant mortality rate leads to a relaxation of natural selection and contributes to hybridization of the population.

Chile↗
PubMed1989

[Genetic epidemiological investigation of cleft lip and cleft palate].

From July 1, 1985 to June 31, 1987, the birth defect monitoring was carried out in 30 hospitals in Anhui Province. It was found that there were 116 cases of cleft lip (CL) and cleft palate (CP) in 46,811 perinatals. The incidence rate of CL and/or CP was 2.48%. It was higher level both in China and abroad. Among these cases, there were 105 cases (90.52%) with CL +/- CP. The incidence rate of CL and CP related to maternal age, birth order, educated level, resident place, occupation and pregnant season was studied. The frequency of first degree relative was 28.26%. That was about thirteen times higher than the birth population frequency. The incidence rate in the offspring of parental-consanguinity was 9.53% (9/944). This is significantly higher than that of non-consanguineous marriage (P less than 0.001). There were three same sex twins affected by CL +/- CP in the 548 pairs of twins, none of the twins with CL +/- CP had identical one. Only one pair of the female twins was affected by different defects. The heritability was found to be 59.6% and was lower than data in other reports. It suggests that environmental factors play a major role in the etiology.

Cleft Lip↗
PubMed1988

Epidemiologic study of gestational trophoblastic diseases in Saudi Arabia.

The role of cultural and socioeconomic diversities (that is, marriage, conceptions at the extremes of reproductive life, consanguinity, economic affluence and such) were analyzed for significance in the epidemiologic study of gestational trophoblastic disease (GTD) in Saudi Arabia. For the study period, the incidence of hydatidiform mole remained unchanged at a mean of one in 448 pregnancies and one in 6,130 for its malignant counterpart. In the instance of molar pregnancies, the youngest (less than 20 years of age) and the oldest (more than 40 years of age) had significantly higher than expected incidence; in contrast, in malignant GTD, the trend was for a higher than expected frequency for the older age group only (more than 40 years of age). Consanguinity showed no significant epidemiologic role.

ABO Blood-Group System↗
PubMed1988

[Blood polymorphism in the study of isolated communities].

Isolated communities offer a unique opportunity for the study of biological and social consequences of consanguinity and migration. The studies of genetic polymorphisms have contributed greatly, not only to knowledge of the genetic constitution of a given individual and population, but also to clarify either relationship between structure and function of polymorphic traits or the susceptibility to multifactorial diseases, in which interaction between the gene and environment cannot be ignored. For over 25 years, we have investigated the effect of consanguinity and genetic polymorphisms in 9 isolated communities in Western Japan. We reported here different values of gene frequency for each polymorphic trait, compared with the neighboring communities and described how we applied these data to clarification of the genetic constitution of isolated communities as well as of genetic susceptibility to some diseases.

Anemia, Aplastic↗
PubMed1985

Inbreeding and matrimonial structure in a Pyrenean community (Ansó, Huesca, Spain), 1712-1982.

Using data from parish records from 1712 to 1982 in a Spanish Pyrenean village, Ansó, the effects of the raw nuptiality, the types of consanguineous marriages and the rate and evolution of inbreeding on the mating structure have been studied. This structure has been modified in the course of time mostly through the secular variations in the frequency of consanguineous marriages. Recent inbreeding decrease in Ansó is related to the population diminution and cultural changes associated with isolate breakdown.

Consanguinity↗
PubMed1985

Incidence in Italy, genetic heterogeneity, and segregation analysis of cystic fibrosis.

Taking advantage of the availability of an archive of consanguineous marriages that gives accurate estimates of consanguinity in Italy, it has been possible to calculate the increase of first- and second-cousin marriages among 624 couples of cystic fibrosis (CF) parents over the general population. From these estimates, the incidence of CF in Italy has been found to correspond approximately to 1/2,000. In turn, the same data have been used to test the hypothesis of genetic heterogeneity of CF, recently proposed, which is based on the presence of two distinct genetic disorders having similar frequencies. If such a hypothesis were true, the number of first-cousin marriages among CF parents should be significantly higher than that observed in our present study. Finally, the segregation analysis of 624 CF sibships has yielded under multiple selection a segregation ratio of 0.252, confirming the recessive mode of inheritance.

Consanguinity↗
PubMedDate not supplied

[Genetic counseling of acrocephalosyndactylia].

The present paper describes a case with clinical and radiological characteristics of Apert's syndrome. He was the first offspring from second cousins marriage. We considered that in this case, consanguinity is an associated feature. Perhaps this case may be the third one reported in the literature with consanguineous parents. We comment the different classifications of the acrocephalosyndactylias for genetic counseling purposes.

Acrocephalosyndactylia↗
PubMed1979

[Distal renal tubular acidosis: report of 3 cases].

Three observations of R.T.A. with nerve deafness are reported. Case 1 and 2 concern consanguinous brothers whose parents are not affected, which confirm the syndrom as an autosomal recessive entity. The third, sporadic, case relates to a 13-year-old non consanguinous girl. Metabolic abnormalities and renal evolution with nephrocalcinosis was such as in Albright disease. However a progressive nerve deafness makes distinction. The authors underline the importance of this sometimes difficult distinction for genetic counseling.

Acidosis, Renal Tubular↗
PubMed1980

Evidence for genetic control of nondisjunction in man.

Data on factors associated with the occurrence of Down syndrome in a highly inbred population were evaluated to investigate the presence of a genetic control of nondisjunction in man. In Kuwait, close consanguinity occurs in 40% of marriages. In its main obstetric hospital, 20 trisomic Down babies out of 11,614 singleton births were delivered over a 12-month period. Chi-square analyses indicate the occurrence of Down syndrome to be linked to two independent factors: consanquinity of parents and maternal age. The relative risk is approximately four times greater for closely related than for nonrelated parents (P less than .005); a possible explanation for this is the existence of a gene that induces mitotic nondisjunction in the homozygous fertilized ovum. An alternative explanation is the existence of an autosomal recessive gene which results in meiotic nondisjunction in the homozygous parents. Consanguinity is usually perpetuated in certain families, or sections of the population, and parents in highly inbred families have a higher probability to be homozygotes for that gene.

Adult↗
PubMed1978

Epidemiology of anti-lymphocyte antibodies in systemic lupus erythematosus.

Lymphocytotoxic antibodies (LCTA) occur in 80% of SLE patients and 40% to 60% of their asymptomatic relatives. They occur equally in consanguineous and nonconsanguineous relatives, are more common with close proband contact, and vary directly with LCTA activity in the proband. LCTA are also increased in laboratory personnel handling SLE blood. Anti-RNA antibodies are found in SLE patients and consanguineous relatives. Both antibodies are primarily IgM in relatives but are IgM and IgG in SLE patients.

Autoantibodies↗
PubMed1984

Association between familial hypercholesterolaemia and church affiliation. Is this the result of sociocultural isolation of migrant farmers in 19th-century South Africa?

The family trees of 57 Afrikaans -speaking familial hypercholesterolaemia (FH) index cases were traced to look for founder surnames, for an association between FH and affiliation to the Gereformeerde Kerk (GK), and for consanguinity. Two possible founder surnames were identified. Each occurred in more than 5% of individuals and both were well known among the founders of the GK. Affiliation to the GK was much more common in our sample (45% of 994 individuals) than in the general population (5%), an overall odds ratio of 7,38. This association was stronger in older generations. There were 21 consanguineous marriages, the two suspected founder surnames and affiliation to the GK featuring prominently among them.

Consanguinity↗
PubMed1982

[Study of an isolated West Indies population. II. Estimation of the inbreeding value (author's transl)].

Saint-Barthélémy, a small island near Guadeloupe, has been isolated since the 18th century. A first estimation of genetic size at each generation gives an estimation of the present inbreeding value due to random genetic drift. It is of the order of half a per cent. A census of matings between closely related persons (first or second cousins), during the three last generation may provide an estimation of the inbreeding value related to choice of mates based on relatedness using Sutter's equation of apparent consanguinity. This estimation is of the same order (0.8%) but is restricted to the cumulative effect of random genetic drift and non-random mating between relatives during these three last generations. A full estimation of remote consanguinity at present time requires a detailed analysis of genealogies.

Consanguinity↗
PubMed1980

[Population structure of forest Nentsee. II. Results of a geneologic study].

Inbreeding and its effect on fertility have been investigated in small (N approximately 1500) population of fisherman, hunters and reindeer breeders living in Northwestern Siberia. Average coefficient of inbreeding in total population was found to be 0.012, ranging from 0.003 to 0.016 between six subisolates. 8% of the total number of matings were matings between close relatives of uncle-niece, first cousins and double first cousins type. Nine polygamic matings were observed among presently living males belonging to elder generation. Comparative analysis of fertility in women whose reproduction had been completed was performed for 64 consanguineous and 120 non-consangineous matings. Insignificant decrease of average number of live births and surviving children was observed in matings of uncle-niece type and could be attributed to the greater number of sterile couples than in control matings. No differences have been observed when consanguineous matings of first cousins type were compared with control families with almost the same proportion of sterile couples. It can be concluded that if inbreeding has any distinct effect on fertility in families in the Forest Nentsee, this happens mainly as a result of increased proportion of sterile matings in inbred part of the population.

Consanguinity↗
PubMedDate not supplied

The epidemiology of juvenile-onset insulin-dependent diabetes mellitus in Turkish children. A retrospective analysis of 477 cases.

The hospital records of 477 patients under 18 years of age with insulin-dependent diabetes mellitus (IDDM) who were followed in the Endocrinology Unit of Hacettepe University Children's Hospital between the years 1969 and 1991 were analyzed for age, sex, residence at time of diagnosis, date of onset of symptoms, date of diagnosis, family history of IDDM, and consanguinity between parents. The distribution of age at diagnosis showed a small peak between 4 and 6 years of age and a main peak between 12 and 14 years. In girls, the main peak appeared between 10 and 12 years, and in boys between 12 and 14. A significant difference was not seen between sexes (239 males and 236 females). The frequency of diagnosis showed seasonal variations the lowest in autumn and the highest in winter. Consanguinity between parents was 23.9 percent, and 10.3 percent of the patients had IDDM in first degree relatives.

Adolescent↗
PubMed1993

Trends in consanguineaous marriage in Karnataka, south India, 1980-89.

Analysis of data on 106,848 marriages in the cities of Bangalore and Mysore, South India, between 1980 and 1989 showed that levels of consanguineous marriage varied between cities through time and by religion. The average coefficient of inbreeding was higher in Bangalore (F = 0.0339) than in Mysore (F = 0.0203), principally reflecting large-scale, post-Independence rural migration into Bangalore. Although there was some evidence of a decline in consanguineous marriages in Mysore, there was no convincing support in either city for earlier projections of a rapid reduction in the popularity of unions between close biological relatives.

Adolescent↗
PubMed1995

[Blood relationship].

In every-day medical practice, blood relationship of spouses hardly ever play an important part. Mainly for genetic counselors and pediatricians the question of consanguinity of a child's parents arises when either a rare, often hereditary, disorder is diagnosed for the first time in a family, or potential parents want information on the risk for hereditary diseases. A probability calculus based on the corresponding hereditary factors of the joint ancestors establishes how likely homozygotes for hereditary diseases among the offspring of [blood]-related spouses - often cousins of the first or second degree - is. Furthermore, proof of the parents' consanguinity may explain a child's unexpected hereditary disease [especially autosomal recessive disorders] and, at the same time, it means a higher risk of repetition for the affected child's desired siblings. Incest represents a special form of genetic risk; this question arises either in connection with the adoption of a child, which was conceived by an incestuous couple, or with such a child's own family planning later on. Even the parents' descent from an ethnically, politically, religiously or linguistically isolated background may gave a similar impact on the appearance of hereditary disorders: an accumulation of rare genes has to be taken into account; factors causing disorders have to be expected among these genes, too. In the following, all major aspects of the situations described above will be given in detail.

Consanguinity↗