Congenital malformations and consanguinity

Effects of consanguinity in a cohort of subjects with certain genetic disorders in Qatar

Background

Consanguineous marriages are common in the Middle East including the Gulf countries. The rate of consanguinity in Qatar is approximately 54%, which are mainly first cousins’ marriages. Previous studies showed that consanguinity increases the prevalence of birth defects and other genetic disorders. Thus, we studied the effects of consanguinity in a cohort of subjects with certain genetic disorders in Qatar.

Methods

This cross‐sectional study was conducted at two centers in Qatar (Hamad Medical Corporation “HMC” and Shafallah “SC”) including 599 Qatari families with certain types of genetic and nongenetic anomalies.

Results

Consanguineous marriages were seen in 397 of 599 (66.2%) Qatari families and first cousin group counts for 65% in Qatari population. In the total cohort and at HMC, all consanguineous marriages had a significantly higher risk of Autosomal Recessive disorders than nonconsanguineous marriages (total cohort: odds ratio (OR) = 1.72; 95% CI: 1.10, 2.71; p = .02; HMC: OR = 2.98; 95% CI: 1.37, 6.09; p = .005). On the other hand, at HMC, nonconsanguinity was significantly related to chromosomal abnormality (OR = 6.36; 95% CI: 1.13, 35.85; p = .036).

Conclusion

Our data suggest a significant role of parental consanguinity in increasing the prevalence of genetic disorders; mainly Autosomal Recessive disorders. Chromosomal abnormality disorders were significantly higher among nonconsanguineous marriages. These results help better inform policy makers on social, educational, and public health initiatives that might mitigate the impact of genetic disease in the Qatari society.

Elevated birth prevalence of conotruncal heart defects in a population with high consanguinity rate

BACKGROUND

The aetiology of conotruncal heart defects is poorly understood and the birth prevalence varies geographically. The known risk factors for developing conotruncal heart defects are as follows: CHD in siblings, genetic chromosomal abnormalities, paternal age >30 years, high parity, low birth weight, prematurity, and maternal diabetes.

OBJECTIVE

The aim of this study was to characterise conotruncal heart defects, birth prevalence, mortality, and morbidity in the population of southern Israel, of whom 75% are Jewish and the rest are mostly Bedouin Arabs.

METHODS

The data were obtained from Soroka University Medical Center database of births and newborns. Conotruncal heart defects cases were identified by ICD9 codes.

RESULTS

During 1991-2011, there were 247,290 singleton live births and 393 conotruncal heart defects in Soroka University Medical Center. The birth prevalence per 10,000 live births of tetralogy of Fallot, transposition of the great arteries, and truncus arteriosus was 9.5, 5, and 1.8, respectively. In the multivariate analysis, Bedouin descent (adjusted odds ratio 2.40, p35 years (1.66, p=0.004), and siblings with congenital heart defects (1.98, p=0.005) were associated with tetralogy of Fallot, and Bedouin descent (1.61, p=0.05), siblings with congenital heart defects (2.19, p=0.004), and diabetes mellitus (7.15, p<0.001) were associated with transposition of the great arteries. In a univariate analysis, Bedouin descent (p=0.004) and congenital heart defects in siblings (p<0.001) were associated with truncus arteriosus.

CONCLUSION

We observed higher birth prevalence of conotruncal heart defects compared with the birth prevalence reported worldwide, specifically among the Bedouins, a population characterised with high consanguinity rate. Therefore, genetic counselling and early fetal echocardiograms should be encouraged, especially in high consanguinity rate populations. Naturally, further educational efforts are needed in order to decrease consanguinity and its related consequences.

Is consanguinity prevalence decreasing in Saudis?: A study in two generations

BACKGROUND

Saudi population is unique in that there is a strong preference for cousin marriages in the general population. We studied the prevalence of consanguinity in educated Saudi females and compared the results with the results obtained in their parents, to access if a generation difference in which extensive educational activities have prevailed to inform the people of the influence of cousin marriages on health, has made any difference in prevalence of consanguineous marriages.

METHOD

A total of 600 Saudi women (421 university students and 179 women attending outpatients' clinics) were interviewed about their own and their parents' consanguinity.

RESULTS

The total consanguinity (first and second cousins) was 29.7% in the parents. Consanguinity was significantly higher among the daughters than the parents, where 37.9% of the 293 married women had consanguineous marriages. The prevalence of consanguinity was studied in different age groups, though no significant pattern was observed. A strong correlation was found between consanguinity of parents and their daughters; consanguinity was highest (52.3%) in the daughters of parents who were themselves consanguineous.

CONCLUSION

The results did not reveal any decrease in the prevalence of consanguinity over a generation. This shows that the tradition of marrying within the family is a preferred practice, despite the awareness that certain genetic disorders occur at a higher frequency in cousin marriages. There is a need at the primary health care level to inform the public of the consequences of this common practice.

Consanguinity and reproductive health among Arabs

Consanguineous marriages have been practiced since the early existence of modern humans. Until now consanguinity is widely practiced in several global communities with variable rates depending on religion, culture, and geography. Arab populations have a long tradition of consanguinity due to socio-cultural factors. Many Arab countries display some of the highest rates of consanguineous marriages in the world, and specifically first cousin marriages which may reach 25-30% of all marriages. In some countries like Qatar, Yemen, and UAE, consanguinity rates are increasing in the current generation. Research among Arabs and worldwide has indicated that consanguinity could have an effect on some reproductive health parameters such as postnatal mortality and rates of congenital malformations. The association of consanguinity with other reproductive health parameters, such as fertility and fetal wastage, is controversial. The main impact of consanguinity, however, is an increase in the rate of homozygotes for autosomal recessive genetic disorders. Worldwide, known dominant disorders are more numerous than known recessive disorders. However, data on genetic disorders in Arab populations as extracted from the Catalogue of Transmission Genetics in Arabs (CTGA) database indicate a relative abundance of recessive disorders in the region that is clearly associated with the practice of consanguinity.

Consanguinity and advanced maternal age as risk factors for reproductive losses in Alexandria, Egypt

BACKGROUND

Consanguinity has been a long-standing social habit among Egyptians. Estimates of consanguinity ratios in different parts of Egypt ranged from 29 to 50%. This study aimed at delineating the role of consanguinity and advanced maternal age on reproductive losses in Alexandria, Egypt.

METHODS

A case-control study, on 730 couples with history of reproductive losses and 2,081 normal couples, was done during the period October, 1998 until August, 2000.

RESULTS

Of the 730 couples with reproductive losses, consanguinity frequency was 68.8% with 56.2% first cousins. Prenatal loss and infant deaths were highly encountered among consanguineous marriages (p < 0.0001). In a multivariate logistic regression analysis, consanguinity between couples increased the relative risk of repeated abortion (OR: 3.95; 95% CI: 3.04-5.14), stillbirths (OR: 10.6; 95% CI: 6.7-17.0), neonatal death (OR: 17.2; 95% CI: 10.8-27.3), post-neonatal death (OR: 14.5; 95% CI: 10.6-19.9) and total reproductive losses (OR: 8.3; 95% CI: 6.9-10.1). A positive association was found between advanced maternal age and repeated abortion (OR: 3.19; 95% CI: 2.04-4.97) as well as total reproductive losses (OR: 2.37; 95% CI: 1.74-3.2).

CONCLUSION

This study, the largest-reported case-control study on reproductive losses in Alexandria, strongly suggests that consanguinity may play a major role in the high rates of prenatal and infant mortality while advanced maternal age has a significant role in the causation of repeated abortion, and they must be taken into account for genetic counseling in Egypt. Because of the possibility of controlling, the study gives clear indications for prevention.

Neural tube defects in the Asir Region of Saudi Arabia

BACKGROUND

The aim of the study was to determine the incidence of neural tube defects (NTD) among admissions at a regional referral hospital in Saudi Arabia, compare trends over several years and note any influence of prenatal folic acid treatment.

PATIENTS AND METHODS

For every NTD admission into the newborn unit of Asir Central Hospital, during the period January 1995 through December 1998, data were collected on the infant and mother and input into a programmed form.

RESULTS

During the period, 64 infants were admitted with NTDs, giving an incidence of 0.78/1000 births in the region. The yearly admission frequency (4.5%-8%) was closely the same (average 6.6%) over the 4-year period (P>0.05). The sex incidence was equal and the major lesions were myelomeningocele (70%) and encephalocele (23%). Thoracolumbar (44.4%) and lumbosacral (40%) regions were the most common sites of spina bifida; encephalocele were largely occipital (93%). A majority (87%) of infants with myelomeningocele were hydrocephalic at birth. Fifty percent of the infants were offspring of consanguineous marriage (first and second cousins). Eighty-three percent of the mothers attended antenatal care, but 70% of these reported late (from the 12th week of pregnancy). Only 25% of the 64 mothers were on folate supplementation during the affected pregnancy and no mother received preconceptional folic acid supplementation.

CONCLUSION

The incidence of NTD in the region appears to be non-declining over the years, a situation which is at variance with experience in Western countries. There is a need to consider an intensive approach to periconceptional folic acid supplementation for Saudi women. Genetic counseling may also be important.

Consanguinity and recurrence risk of stillbirth and infant death

OBJECTIVES

The aim of this study was to estimate the recurrence risk for stillbirth and infant death and compare results for offspring of first-cousin parents with results for offspring of unrelated parents.

METHODS

The study population consisted of all single births with a previous sibling born in Norway between 1967 and 1994. Altogether, 629,888 births were to unrelated parents, and 3466 births were to parents who were first cousins. The risk of stillbirth and infant death was estimated for subsequent siblings contingent on parental consanguinity and survival of the previous sibling.

RESULTS

For unrelated parents, the risk of early death (stillbirth plus infant death) for the subsequent sibling was 17 of 1000 if the previous child survived and 67 of 1000 if the previous child died before 1 year of age. For parents who were first cousins, the risk of early death for the subsequent sibling was 29 of 1000 if the previous child survived and 116 of 1000 if the previous child died.

CONCLUSIONS

The risk of recurrence of stillbirth and infant death is higher for offspring of first-cousin parents compared with offspring of unrelated parents.

A study of possible deleterious effects of consanguinity

The aim of the study was to determine whether consanguineous marriages result in reproductive wastage and an increased incidence of illness in the offspring in a community with a long history of inbreeding and an expected high rate of consanguineous marriage. A representative sample of 2200 women aged > or = 15 years from Dubai and Al Ain, two cities in the United Arab Emirates, representing on the one hand a modern metropolis and on the other a traditional society, were studied. A questionnaire, which included questions on age, parity, gravidity, number of stillbirths, number of abortions, number of children alive, neonatal deaths and specific illnesses in children, was administered by nurses in antenatal and gynaecological clinics in the two cities. The rate of consanguineous marriage was 50.5% and parity, gravidity, ages and number of children were similar in consanguineous and non-consanguineous groups. There was no significant difference in rates of abortion, stillbirth and neonatal death between the two groups. Overall, there was statistically significant higher reproductive wastage in consanguineous couples, but when the category of less than second cousins was excluded from the consanguineous group no difference was found in reproductive wastage between consanguineous and non-consanguineous marriages. Children born to consanguineous unions also had significantly higher incidences of illnesses (37.1%) than those of non-consanguineous unions (29%). The occurrence of malignancies, congenital abnormalities, mental retardation and physical handicap was significantly higher in offspring of consanguineous than non-consanguineous marriages. In conclusion, consanguinity did not result in reproductive wastage, but was found to be an important factor in the causation of specific illnesses in offspring.

Consanguinity among the Saudi Arabian population

This study was conducted on 3212 Saudi families to investigate the prevalence of consanguineous marriages. The families were interviewed and the information on the relationship between the husband and wife was obtained. The overall rate of consanguinity shows that 57.7% of the families screened were consanguineous. The most frequent were first cousin marriages (28.4%) followed by distant relative marriages (15.2%) and second cousin marriages (14.6%). The families were grouped according to the province of their origin and the consanguinity rates were calculated accordingly. There were slight differences in the consanguinity rates in the five provinces, which ranged from 52.1% to 67.7%. In each province first cousin marriages were the most frequently encountered pattern, ranging from 17.9% to 40.9%. The inbreeding coefficient (F) was calculated for each province and ranged from 0.020 to 0.030. Within each province, there were several significant differences among the populations in the different areas. The highest rate of consanguinity was 80.6% in Samtah and the lowest rate was around 34% in Abha in the South Western province. These results place Saudi Arabia among the countries of the world with a high rate of consanguinity. The possible consequences of increased consanguinity are presented and discussed.

Congenital malformations, reproductive wastage and consanguineous mating

A study was undertaken in Jawaharlal Institute of Postgraduate Medical Education and Research, Pondicherry, South India, to understand the relation between congenital developmental disorders and consanguinity and also reproductive wastage and consanguinity. Four hundred children with existing congenital developmental disorders were studied with regard to their consanguineous parentage and compared with 1,000 randomly selected patients attending the paediatric outpatient department. There was a significantly higher prevalence of consanguinity in the study group (p < 0.001) and greater frequency in rural areas. The common types of consanguineous marriages were between first cousins (50.6%) and uncle and niece (42.4%). Frequency of consanguinity was not significantly related to religion and caste. The mean coefficient of inbreeding was 0.056. Consanguinity had no significant effect on average pregnancy rate and reproductive wastage. The frequency of consanguinity was significantly higher especially with autosomal recessive disorders (p < 0.001), congenital heart diseases (p < 0.001), multiple malformations (p < 0.001), neurological malformations (p < 0.005), chromosomal disorders (p < 0.01), genitourinary disorders (p < 0.02) and mental retardation-developmental disorders (p < 0.02). These observations stress the need for communicating the deleterious effects of inbreeding to the public through regular health education.

Perinatal mortality in Bahrain

A review of 583 perinatal deaths at the Ministry of Health hospitals in Bahrain, during the years 1985-1987 revealed a perinatal mortality rate of 19.6 per 1,000 total births. Lethal congenital malformations accounted for 145 (24.9%) deaths. Of the 438 normally formed infants there were 42.2% antepartum, 115 (26.3%) intrapartum and 138 (31.5%) early neonatal deaths; in 82.7% of cases the death was considered to be unavoidable. The population of Bahrain for 1986 according to the Central Statistics Organization (1) was 435,065, the majority of which was served by the Ministry of Health Maternity Service with approximately 10,000 deliveries per annum. The Ministry of Health provides maternity services through one main maternity hospital and 2 peripheral hospitals with consultant obstetric care. In addition to these, there are 3 maternity units run by midwives. High risk cases are usually delivered in the main hospital as there is a neonatal intensive care unit attached to it. The latter also acts as a referral centre for all sick babies in Bahrain. An analysis of the causes of perinatal deaths is an effective way of assessing the efficiency of maternity services. The objective of this study was to identify and improve the various factors influencing perinatal mortality in Bahrain.