Frequency of consanguinity among the population of Beni Abbes
The high level of consanguinity detected (55.06%) could be explained by the fact that individuals opt for consanguineous marriage as a tradition. The social structure of the Beni Abbes region ensures that families are in many cases very united by socio-economic factors that force members of these families to live in close proximity.
This frequency is significantly higher than the Algerian average of 38.8% [16]. With regard to the distribution by type of kinship in the population (first cousins marriages and second cousins marriages), a clear preference for 1st cousin marriages (37.08%) is found among the studied couples. This result is in perfect agreement with those recorded in the populations of Tlemcen Mountains and Highlands [15]. However, it does not agree with the results recorded in the populations of Sabra, where there has been a clear preference for 2nd cousin marriages [17].
In his study on consanguineous marriages in Beirut in 1986, Khalt M indicates that the type of first cousin marriages is most prevalent among Arab-Muslim populations and is a characteristic feature of this group [20].
Intergenerational variation of consanguineous marriages among the population of Beni Abbes
These results obtained testify the existence of continuity in the practice of marriages between relatives. The tendency to marry a first cousin is preferable both in the generation of the studied couples 67.35% than in the parents 52.08% and in grandparents 62.85%. The high rate of consanguinity across the three generations can be explained by the fact that Beni Abbés has always been a genetic isolate [21] and is likely to continue to be so.
Inter-local variability in the frequency of consanguineous unions of the population of Beni Abbes compared to those of populations in geographically neighboring regions
High consanguinity rates in the three populations of Beni ounif, Beni Abbés, and Igli which respectively 65.65%, 55.06%, and 49.28% can be explained by the fact that these three populations were already genetic isolates according to the 1989 study by Bachir and Abdulkader on the distribution of frequencies of blood groups and their genes on populations in southwestern Algeria [21].
The comparison of the inbreeding rate of the population of Beni Abbés with some populations of geographically neighboring regions (Fig. 2) shows that it is lower than the frequencies recorded in the highlands of the wilaya of Tlemcen [15], relatively close to those recorded in Ghardaïa [16], and it is well below the frequencies recorded in Biskra and El Oued [16].
Comparison of the frequency of consanguineous marriages of the population of Beni Abbés to those of the Arab-Muslim world
The high consanguinity rate recorded at the end of the study carried out on the population of Beni Abbés (56.06%) is one of the highest rates in the Arab Muslim world; it reinforces the results obtained by the survey conducted in 2007 in 11 wilayas (from different regions) by the National Foundation for Medical Research (FOREM) that consanguineous marriage is a widespread practice in Algeria and enriched the scientific literature in this field.
Biological effects of consanguineous unions on abortion and mortality
Effects of consanguinity on abortion
The correlation established between consanguinity and abortion in our population is consistent with those in Iraq [27] and Turkey [28], who reported twice as many abortions among first cousin consanguineous couples as in non-consanguineous couples.
On the other hand, our results do not agree with the results of studies realized in Pakistan that has shown lower rates of abortions in families where consanguinity is customary across successive generations, presumably because of the increasing effect homozygosity on fetal development [29].
Influence of consanguinity on mortality
The values of relative risk (1.55) and attributable risk (0.23) mean that the risk of mortality of children from consanguineous marriages is high compared to that of children from non-consanguineous marriages.
Our results are consistent with those Abbad et al. [13] and Moussouni et al. [17] which unambiguously confirm that prenatal and postnatal mortality rates and infant morbidity increase when couples are in consanguineous unions.
These results reinforce those achieved since 1984 [14], 2007 [16], and 2017 [17], particularly with regard to the negative effects of consanguinity on public health in Algeria, and alert the public authorities to the need to install genetic counseling in services to level of all health structures to reduce these effects.
Despite the results recorded, difficulties in particular social (it was very difficult to convince the subjects to join the survey) which explains the size of the sample compared to the relatively long time to realize the study.