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PubMedDate not supplied

Trends in patrilineal parallel first cousin marriages among Israeli Arabs: 1949-1995.

BACKGROUND: Consanguineous marriages are one of the means by which lineal clans maintain themselves. As it happens, there is a biological price to be paid for consanguinity, which is strongly felt particularly in populations where mortality is low. PRIMARY OBJECTIVE: This study seeks to estimate trends in consanguinity among the Muslim and Druze populations of Israel during the period 1949-1995. METHODS: The Israel Population Register is a continuously updated disk record of all current and former citizens. A copy of this record, as of 31 October 1995, was used to construct a file of all Muslim and Druze marriages that had taken place between 1949 and 1995. The marriage records include the given names of the paternal grandfathers of husband and wife. Couples whose grandfathers have the same name may be parallel patrilineal first cousins. A probability algorithm was constructed which provides an estimate, for each name, of how many of these couples are in fact first cousins. The estimates are then summed over all names to provide a population estimate. This procedure was carried out separately by religion, marriage period and region. RESULTS AND CONCLUSIONS: Statistically significant declines in consanguinity were found for the Muslim populations of northern Israel, since 1965, and for Jerusalem, since 1949. For the Bedouin of the Negev only a temporary decline was found, for a short time after the reopening of the borders with Gaza, Sinai and the West Bank in 1967. Significant declines in consanguinity were also found for the Druze of northern Israel, after 1982. It is considered, though not demonstrated, that the secular declines are associated with increasing levels of education and urbanization known to have occurred in these populations.

Algorithms↗

PubMed1987

An epidemiologic approach to the evaluation of the effect of inbreeding on prereproductive mortality.

Although many studies report deleterious effects of inbreeding on prereproductive mortality (death before age 20 years), such effects are usually measured in terms of genetic load, a concept much debated in the literature. To evaluate the public health impact of inbreeding on prereproductive mortality in terms of relative and attributable risks, the authors reviewed 31 studies with 294 observations comparing various stages of infant and child mortality in offspring of unrelated parents with offspring of first cousin, first cousin once removed, and second cousin marriages, respectively. Compared with offspring of unrelated parents, offspring of first cousin marriages have a higher risk of prereproductive mortality (median relative risk (RR) = 1.41, signed-rank test, p less than 0.01). Offspring of first cousin once removed and second cousin marriages had median relative risks of 1.16 and 1.26, respectively. Countries with relatively higher rates of consanguineous marriages (greater than 5%) had lower median relative risks than did countries with lower consanguinity rates. Also, the higher the mortality rate in the population, the lower the effect of consanguinity (median relative risk). Because of the rarity (less than 5%) and declining trends of consanguineous marriages in many places of the world, and because of their modest effect on prereproductive mortality (RR less than 2.0), it can be shown that the attributable risk of prereproductive mortality due to consanguineous marriages is less than 5%. Except for a few places with very high inbreeding levels, inbreeding has a minor impact on mortality in the prereproductive period.

Consanguinity↗

PubMed1986

Detection of lymphocytotoxic antibodies in relatives of patients with type I diabetes.

Concentrations of lymphocytotoxic antibodies were measured in serum samples from 19 patients recently diagnosed as having type I diabetes and 43 healthy relatives (33 consanguineous and 10 non-consanguineous). The specificity of the reaction was tested at 15 degrees C and 37 degrees C against T lymphocytes and purified helper/inducer and cytotoxic/suppressor subsets. The concentrations of lymphocytotoxic antibodies in each of the three test groups were significantly higher than those in controls (type I patients, p less than 0.005; consanguineous relatives, p less than 0.001; and non-consanguineous relatives, p less than 0.002). The frequency of detection of the antibodies was also greater in each of the study groups (p less than 0.01, p less than 0.01, and p less than 0.05, respectively). Cytotoxicity affected both subsets at 15 degrees C but only cytotoxic/suppressor cells at 37 degrees C. The findings of lymphocytotoxic antibodies in healthy relatives of type I diabetics, irrespective of consanguinity, suggests that an environmental agent such as a virus is at least partially responsible for this lymphocytotoxic effect. Furthermore, the residual cytotoxic/suppressor cell killing at 37 degrees C could explain the defect of suppressor cells observed in these patients.

Adolescent↗

PubMed1983

Genetic aspects of myopia among the Shia Muslim Dawoodi Bohras of Udaipur, Rajsthan.

359 sibs from 92 families, where any one member of the family (basic unit of study) was found to be affected, were screened for myopia. Data on age at onset, parity and severity were studied in relation to consanguinity. Significant consanguinity differentials in the manifestation of myopia were seen. Offspring who were the product of a consanguineous mating manifested myopia more frequently as compared to the offspring from the non-consanguineous matings (control group). Males from consanguineous matings were affected in a higher frequency and manifested myopia at early ages. Myopia was found to be birth order-dependent. Pedigree analysis has shown that myopia is not a monogenic trait. The most plausible mode of inheritance of myopia seems to be polygenic with variable expressivity, and shows gene dosage effect.

Birth Order↗

PubMed2005

Genetics, obesity, and environmental risk factors associated with type 2 diabetes.

AIM: To determine the association between consanguineous marriages, obesity, and environmental risk factors associated with type 2 diabetes, in the adult Qatari population. METHODS: The case-control study was carried out among diabetic patients and healthy subjects at the Primary Healthcare Clinics (PHCs) and the survey was conducted from February to November 2003. The study included 338 cases (with diabetes) and 338 controls (without diabetes). Face-to-face interviews were based on a questionnaire that included variables such as age, gender, socioeconomic status, parity, income level, cigarette smoking, physical activity, body mass index (BMI), obesity, and lifestyle. Their health status was assessed by medical conditions, family history, physical examination, blood pressure, blood glucose, blood count, lipid profile, cholesterol total, HDL, LDL, and triglycerides analysis. RESULTS: The mean age (in years-/+standard deviation) of cases versus controls was 45.5-/+8.9 vs 42.4-/+8.0, P<0.001. The study revealed that there were statistically significant differences between diabetic and control subjects with respect to body mass index, low educational level, consanguineous marriage, and number of children (P<0.001). The obesity was considerably more frequent among diabetes subjects (P<0.001). Self reported family history (in first degree relatives) of diabetes (62.1% vs 44.4%, OR=2.06, 95% confidence interval (CI)=1.49-2.83) P<0.001) was prominent among diabetic subjects. The diabetes was significantly common among the consanguineous marriages of the first degree relatives compared with the control group (33.1% vs. 24.6%, OR=1.59, 95% CI=1.11-2.29), P=0.008). Systolic blood pressure (P=0.023) and glucose fasting (P<0.001) levels were significantly higher in diabetic patients than in control subjects. The logistic regression model showed that smoking (OR=2.42 95% CI=1.66-3.54, P<0.0001); degree of consanguinity (OR=1.38 95% CI=1.13-1.69, P=0.002), BMI (OR=1.41 95% CI=1.12-1.76), P=0.003), level of education (OR=1.23 95% CI=1.04-1.45, P=0.017), number of children (OR=1.34 95% CI=1.02-1.77, P=0.037), and systolic blood pressure (OR=1.01 95% CI=1.00-1.02, P=0.044) were considered as associated risk factors for diabetes. CONCLUSION: The present study revealed that obesity, consanguinity, blood pressure, total cholesterol, HDL-cholesterol, and triglycerides were more prevalent in diabetic patients. The characterization of these factors will contribute to defining more effective and specific strategies to screen for and control diabetes and cardiovascular disease in a developing country.

Adult↗

PubMed1981

Genetic implications of mating structure in a Caribbean isolate.

Mating patterns in the population of St. Barthélémy, French West Indies, are examined to evaluate the expected genetic consequences of consanguinity avoidance and of failure to mate due to celibacy and emigration. Nearly 60% of all individuals reaching mating age on "St. Bart" never contribute to the gene pool of succeeding generations. This greatly reduces the effective population size and, therefore, increases genetic drift or random inbreeding. The consequent loss of heterozygosity is partially countered by the fact that the individuals who fail to reproduce within the population tend to be more closely related to the population than are those who do reproduce. This nonrandom failure to mate results in nonrandom inbreeding, which reduces total pedigree inbreeding. Total inbreeding is also reduced by consanguinity avoidance. However, the effect of avoiding close consanguineous matings is, to some extent, reversed by an apparent preference for more distant relationships, especially with second cousins. Generally similar results are found for the related Northside French population of St. Thomas. U.S. Virgin Islands. A recently developed mathematical model predicts the expected effect on heterozygosity of partial or complete avoidance of, or preference for, any combination of consanguineous matings, and also takes into account nonrandom failure to mate. Application of this model to these two populations suggests that under some circumstances nonrandomness in celibacy and emigration may have a greater influence on genotype distributions than does consanguinity avoidance.

Consanguinity↗

PubMed1993

Inbreeding patterns in the Basque Country (Alava Province, 1831-1980).

A considerable number of studies have shown that Spain is one of the countries on the European continent with a high level of inbreeding and that, in general, this level decreased more quickly and later than the levels in the rest of Europe. The types and frequencies of consanguineous marriages (up to third cousins), the mean inbreeding coefficient, and secular trends have been studied within the Basque Country (Alava Province) using information from ecclesiastic dispensations from 1831 to 1980. A total of 5583 consanguineous marriages were registered in Alava over the whole period (150 years), and 79 different categories of relationship were observed. The analysis of the structure of consanguinity has shown some appreciable levels of close consanguineous unions: 0.08% (uncle-niece or aunt-nephew marriages) and 0.96% (first-cousin marriages) of the total number of marriages. This seems to be a common phenomenon among provinces of northern Spain. The rates of total consanguinity and the mean coefficient of inbreeding in the population of Alava from 1861 to 1980 were 4.62% and 0.00124, respectively. The temporal trend pattern of inbreeding in Alava closely fits the pattern observed in other large European populations: France, Italy, and Belgium. This early fall in the level of inbreeding in Alava compared to the levels found in both large and small populations in central and western Spain might be due to the early industrial development of the Basque Country and the resulting loss of importance of landownership.

Consanguinity↗

PubMed2002

Finding genetic contributions to sporadic disease: a recessive locus at 12q24 commonly contributes to patent ductus arteriosus.

The causes of many sporadic diseases are unexplained; the contribution of recessive loci with reduced penetrance is one possibility that has been difficult to explore. We describe an approach to this problem by first searching for diseases with higher prevalence in populations with high rates of consanguinity, then determining whether disease cases are more commonly the product of consanguinous union than controls in such populations, followed by analysis of genetic linkage in consanguinous cases. We demonstrate the utility of this approach by investigation of congenital heart disease in Iran. We found that patent ductus arteriosus (PDA), a common congenital heart disease, accounts for a higher fraction of congenital heart disease in Iran (15%) than in the United States (2-7%). Moreover, Iranian PDA cases demonstrated a marked increase of parental consanguinity (63%), compared with the general Iranian population (25%) or control cases with tetralogy of Fallot (30%). The recurrence of PDA among siblings was 5%. A genomewide analysis of linkage in 21 unrelated consanguinous PDA cases demonstrated a multipoint logarithm of odds score of 6.27 in favor of linkage of PDA to a 3-centimorgan interval of chromosome 12q24, with 53% of kindreds linked. These findings together establish a recessive component to PDA and implicate a single locus, PDA1, in one third or more of all PDA cases in Iran; they further suggest a role for this locus in PDA worldwide. Finally, these results suggest a general approach to the identification of recessive contributions to sporadic diseases.

Chromosome Mapping↗

PubMed1991

Inbreeding in Finland.

We have compiled data on the frequency of first-cousin marriages in Finland using royal dispensation records for the time period 1810-1872 and national population statistics for the time period 1878-1920. For the earlier period, 0.315% of Finland's marriages were contracted between first cousins (2,331 of 739,387). During the second time period, 0.174% of Finland's marriages took place between first cousins (1,325 of 761,976). These figures, which yield average kinship coefficients of 0.00020 and 0.00011, respectively, show that the level of inbreeding in Finland due to first-cousin marriage has been quite low. An analysis of individual parishes shows that first-cousin marriages are, on average, substantially less frequent than predicted by a random-mating model. In order to evaluate determinants of first-cousin marriage, several predictive variables have been examined: parish ethnic composition (proportion of Swedish and Finnish speakers), husband's occupation (graded into 6 socioeconomic levels), geographic distance between spouses' premarital residences, population density, parish endogamy, and urban vs. rural residence. Various logistic and linear regression models were analyzed in which consanguinity was the dependent variable. The best predictors of consanguinity were ethnic composition and occupation. The other variables were not in general significant predictors. These results show that many of the "mate availability" factors that would be predicted theoretically to account for consanguinity variation (population density, geographic isolation, urban vs. rural residence) do not. Instead, the best predictors of consanguinity at the first-cousin level are cultural factors such as ethnicity and occupation. Evaluation of cultural variables can provide a greatly enriched interpretation of complex biosocial phenomena such as inbreeding.

Consanguinity↗

PubMed2004

Clinical investigation of genetic contributions to childhood-onset epilepsies and epileptic syndromes.

Although there have been major advances in the understanding of the molecular bases of certain inherited epilepsy syndromes, clinical studies are still needed to verify the possible genetic contributions to common epilepsies. We examined the proportions of positive family histories of epilepsy (within second-degree relatives) and consanguinity (within first-degree relatives) in 311 probands with childhood-onset epilepsy, and found that they had high family history rates of epilepsy (19.3%) and consanguinity (6.1%). A positive family history of epilepsy was found more in probands with generalized epilepsy than in ones with localization-related epilepsy, and more in probands with idiopathic/cryptogenic epilepsy than in ones with symptomatic epilepsy. However, on analysis after the symptomatic epilepsies had been divided into two categories, probands with pre- or perinatal symptomatic generalized epilepsy and ones with postnatal symptomatic localization-related epilepsy showed high positive family history rates, similar to ones with idiopathic/cryptogenic epilepsy. On the other hand, a positive family history of consanguinity was noted more in probands with generalized epilepsy than in ones with localization-related epilepsy, but there was no significant difference between probands with idiopathic/cryptogenic epilepsy and ones with symptomatic epilepsy. These findings suggest that in addition to the hereditary effect on idiopathic/cryptogenic epilepsy, a genetic susceptibility may contribute to the development of pre- or perinatal symptomatic generalized epilepsy, and to that of postnatal symptomatic localization-related epilepsy. Furthermore, a genetic predisposition seems to have an influence through consanguinity on the etiologies of both idiopathic/cryptogenic and symptomatic generalized epilepsies.

Adolescent↗

PubMed2001

Classification of epilepsy syndromes and role of genetic factors.

In this report the types of epilepsy syndromes seen in children in a tertiary referral center in Beirut, Lebanon were studied and the importance of consanguinity and family history in the occurrence of these syndromes was investigated. Records of 230 pediatric patients evaluated during a 1-year period with the diagnosis of single seizure, febrile seizure, or epilepsy were reviewed. Each patient was classified according to the International League Against Epilepsy classification. The occurrence of consanguinity, of family history of febrile seizures or epilepsy, and of other variables was noted. Thirty-six percent of patients were diagnosed with localization-related epilepsy, 21.7% with generalized epilepsy, 11.7% with undetermined generalized or focal, and 24.3% with special syndromes. Twelve percent of patients were diagnosed with idiopathic, 15.1% with symptomatic, and 30.3% with cryptogenic epilepsies. Consanguinity was more common in patients with symptomatic and cryptogenic epilepsies than in patients with idiopathic epilepsies or with incidental seizures (P < 0.05). Family history of epilepsy was more common in patients with symptomatic, cryptogenic, and idiopathic epilepsies than in patients with incidental seizures (P < 0.05). Family history of febrile seizures but not consanguinity was more common in patients with febrile seizures (P < 0.05). We conclude that genetic factors are important not only in idiopathic epilepsies and febrile seizures but also in cryptogenic and symptomatic epilepsies.

Adolescent↗

PubMed2002

Epidemiological and genetic study of 121 cases of oral clefts in Kuwait.

AIM: The aim of the study was to ascertain some epidemiological factors such as sex and consanguinity that may be associated with cleft lip with or without cleft palate (CL +/- CP) in Kuwait as well as to conduct genetic segregation analysis of these families. SETTING AND SAMPLE POPULATION: A total of 113 families ascertained through 121 CL +/- CP and CP surgical probands in Kuwait. The frequencies of cleft types and the epidemiological variables were calculated using SPSS version 5.0 software. Chi-square for goodness-of-fit test was used to test the significance of the associated epidemiological variables to facial clefts. Genetic segregation analysis was performed on 76 families with extended pedigrees and included only those with non-syndromic CL +/- CP (NS CL +/- CP). Major locus segregation analysis was used to fit models to the observed family patterns under Class A regressive models as implemented by REGD routine in S.A.G.E. release 4.0. A test for heterogeneity was also conducted to complete data set in addition to two subsets: Arabs and nomads. RESULTS: Of the 121 patients, 34(28.1%) had CP, 30(24.8%) had CL and 57 (47.1%) had CL + CP. The male to female ratio was 0.89 for CP, 1.14 for CL, 1.35 for CL + CP and 1.2 for all the clefts. The percentage of consanguineous families among those with a positive family history (60%) was not significantly different from that of the general population (54.3%), whereas for all the families with clefts the percent consanguineous was significantly lower (38%). No evidence of heterogeneity in the results between the Arab and nomad subsets was observed. The results for the major locus segregation analysis were inconclusive. CONCLUSION: No definite association was observed between consanguinity and the occurrence of facial clefts in Kuwait. General transmission models in the full data set showed no evidence of heterogeneity in the results between the Arab and nomad subsets.

Adolescent↗

PubMed1996

Childhood neuromuscular disorders: a decade's experience in Saudi Arabia.

The study describes the pattern of childhood neuromuscular disorders seen in a decade (1982-1992) at King Khalid University Hospital, Riyadh, Saudi Arabia. Similar data are scanty outside Europe and North America, and lacking in Saudi Arabia. Eighty-four children (< or = 16 years) were assigned to an entity of neuromuscular disease following review of the clinical, biochemical and neurophysiological data, and after re-examination of the histological and histochemical features of the muscle biopsies. Of the 84 ascertained cases, 40 (48%) had different forms of muscular dystrophy (MD), 26 (31%) had one of the various types of spinal muscular atrophy (SMA) and two (2.4%) hereditary motor and sensory neuropathy type I. The rest were miscellaneous cases including one (1.2%) with dermatomyositis. Of the dystrophies, severe childhood autosomal recessive muscular dystrophy (SCARMD) was more prevalent (30%) than Duchenne type (25%), conforming with observations from North African countries known to have a high incidence of consanguineous marriages. Family history of other cases of SCARMD included three males and three females, one of whom died at 15 years, and consanguinity was evident in 63%. Congenital MD, inherited in an autosomal recessive pattern, was also common (30%). A history of consanguinity was present in 55%. Of the 26 cases of SMA, type I (Werdnig-Hoffman disease) was the most prevalent (69%). Consanguinity was ascertained in 65% of SMA families and histories revealed another 14 affected siblings. Autosomal recessive forms seem to constitute the bulk of neuromuscular disorders in Saudi Arabia.

Adolescent↗

PubMedDate not supplied

Inbreeding effects on fertility and sterility: a case-control study in Saguenay-Lac-Saint-Jean (Québec, Canada) based on a population registry 1838-1971.

Effects of inbreeding on couples' fertility and primary sterility were investigated in five marriages between uncle and niece, 251 marriages between first-degree cousins, and 358 marriages between first-degree cousins once removed from Saguenay-Lac-Saint-Jean. Three control groups matched on the demographic and socioeconomic characteristics of the consanguineous couples were created. The number of children born to each couple was extracted from a computerized population registry. The level of primary sterility was found to be similar in all consanguineous and non-consanguineous groups. The mean number of children in all three consanguineous groups was not found to be significantly different from that calculated in their respective control groups (p > 0.05). These results are compatible with those obtained in virtually all the studies reported thus far in different populations.

Case-Control Studies↗

PubMed1994

Inbreeding and congenital heart diseases in a north Indian population.

The study was performed in six mohallahs (colonies) of Aligarh City (North India). All six mohallahs are predominantly inhabited by Qureshi (meat sellers, a highly endogamous group) Muslims. A total of 1721 infants and children up to the age of 6 years were examined to determine the incidence of congenital heart diseases (CHD) in relation to the degree of consanguinity of the parents. Around 43% of the subjects were the offspring of consanguineous marriages including second-cousin, first-cousin-once-removed and first-cousin. A higher percentage of CHD was found in the offspring of consanguineous marriages: about 3.37% out of 741 children as compared to 1.22% in 980 offspring of non-consanguineous marriages, whereas in the first-cousin offspring, the percentage of CHD rose to 4.41%. The differences were found to be statistically significant. The present study suggests a genetic influence and also casts doubt on the applicability of a polygenic threshold model to all forms of cardiac malformation.

Chi-Square Distribution↗

PubMed1988

Traditional Arabian marriages and mental health in a group of outpatient Saudis.

This is a prospective study of 150 consecutive outpatients who were either married or divorced. Marriage custom in Saudi Arabia is unique to the culture of that country and several different kinds of marriage are identified: arranged marriage of cousins; marriage of a couple who have not met before consummation; marriage of a couple who have met once before consummation; forced marriage; and, rarely, marriage preceded by a period of courtship. Marital discord defined by the patients as fully or partially responsible for their presenting symptoms, was correlated with the different kinds of marriage. Discord was found to be more likely when the couple had never met or when there had been a period of courtship; more likely associated with anxiety and dysthymic disorders; and to affect females more than males. Polygamy was a definite stress. The consanguinous marriage had a higher rate of marital discord than the non-consanguinous, but this was found to be not statistically significant. In 40% of discordant, consanguinous marriages the discord was directly related to the degree of consanguinity.

Anxiety Disorders↗

PubMed2003

A locus for asphyxiating thoracic dystrophy, ATD, maps to chromosome 15q13.

Asphyxiating thoracic dystrophy (ATD), or Jeune syndrome, is a multisystem autosomal recessive disorder associated with a characteristic skeletal dysplasia and variable renal, hepatic, pancreatic, and retinal abnormalities. We have performed a genome wide linkage search using autozygosity mapping in a cohort of four consanguineous families with ATD, three of which originate from Pakistan, and one from southern Italy. In these families, as well as in a fifth consanguineous family from France, we localised a novel ATD locus (ATD) to chromosome 15q13, with a maximum cumulative two point lod score at D15S1031 (Zmax=3.77 at theta=0.00). Five consanguineous families shared a 1.2 cM region of homozygosity between D15S165 and D15S1010. Investigation of a further four European kindreds, with no known parental consanguinity, showed evidence of marker homozygosity across a similar interval. Families with both mild and severe forms of ATD mapped to 15q13, but mutation analysis of two candidate genes, GREMLIN and FORMIN, did not show pathogenic mutations.

Asphyxia↗

PubMed2005

Genetic contribution to high neonatally lethal malformation rate in the United Arab Emirates.

OBJECTIVES: We examined the contribution of genetic disorders to congenital anomalies (CA) causing neonatal deaths in the Al Ain Medical District (AMD) in the United Arab Emirates (UAE) because of the high consanguineous marriage rate in the community. METHODS: Charts of all neonatal deaths in the three perinatal units, which accounted for 99% of all births in AMD (1992-2000), were studied. Data regarding pregnancy, a family history including the level of parental consanguinity, the results of genetic evaluations and neonatal outcomes were recorded as part of an ongoing malformation surveillance system. Causes of death were based on clinical, laboratory and imaging findings. RESULTS: Of the 508 neonates who died, 212 (42%) had CA, which were the leading cause of death. Forty-four percent of the CA were due to definite genetic disorders and 75% of these were single gene defects. Multisystem malformations were the commonest congenital malformations. Parental consanguinity was associated with a 2-fold increased risk of non-chromosomal multisystem malformations. CONCLUSIONS: Lethal malformations were the leading cause of neonatal deaths, and parental consanguinity was associated with an increased risk of autosomal recessive disorders. The results underscore the importance of genetic screening and counseling in strategies for further significant reductions in the neonatal mortality rate in the UAE.

Abnormalities, Multiple↗