Consanguinity and multiple sclerosis susceptibility: A case control study

Identification and structural characterization of a pathogenic ARSA missense variant in two consanguineous families from Jammu and Kashmir (India) with late infantile metachromatic leukodystrophy

BACKGROUND

Metachromatic leukodystrophy (MLD) is a rare lysosomal storage disorder caused by a deficiency of Arylsulfatase A (ARSA) enzyme activity. Its clinical manifestations include progressive motor and cognitive decline. ARSA gene mutations are frequent in MLD.

METHODS AND RESULTS

In the present study, whole exome sequencing (WES) was employed to decipher the genetic cause of motor and cognitive decline in proband's of two consanguineous families from J&K (India). Clinical investigations using radiological and biochemical analysis revealed MLD-like features. WES confirmed a pathogenic variant in the ARSA gene. Molecular simulation dynamics was applied for structural characterization of the variant.

CONCLUSION

We report the identification of a pathogenic missense variant (c.1174 C > T; p.Arg390Trp) in the ARSA gene in two cases of late infantile MLD from consanguineous families in Jammu and Kashmir, India. Our study utilized genetic analysis and molecular dynamics simulations to identify and investigate the structural consequences of this mutation. The molecular dynamics simulations revealed significant alterations in the structural dynamics, residue interactions, and stability of the ARSA protein harbouring the p.Arg390Trp mutation. These findings provide valuable insights into the molecular mechanisms underlying the pathogenicity of this variant in MLD.

Genetic etiology of hereditary hearing loss in the Gulf Cooperation Council countries

The past 30 years have seen an exponential growth concerning the identification of genes and variants responsible for hereditary hearing loss (HL) worldwide. This has led to a huge gain in our understanding of molecular mechanisms of hearing and deafness, which improved diagnosis for populations with hereditary HL. Many communities around the world, especially in the Middle East and North Africa, have a high prevalence of consanguineous marriages. Congenital monogenic conditions, such as recessive HL, are more common in these populations due to high consanguinity rates. Many studies have shown that high rates of consanguinity, endogamy, and first cousin marriages were observed in the six countries of the Gulf Cooperation Council (GCC). The intent of this study is to investigate the etiology of HL in the GCC region. A deep literature review of genes and variants responsible for HL in this region revealed 89 recessive DNA pathogenic variants reported in 138 cases/familial cases. A total of 21 genes responsible for non-syndromic hearing loss (NSHL) and 17 genes associated with syndromic hearing loss (SHL) were reported in cases from the GCC region. Out of 156 reported affected cases, 112 showed HL only, and 44 showed HL associated with other clinical manifestations. This data suggests that in the GCC region 72% of HL forms are non-syndromic and 28% are syndromic. For individuals with NSHL, 66% of variants were detected in four genes (GJB2, OTOF, TMC1 and CDH23), with a predominance of variants located in the GJB2 gene (37.5%). However, among SHL, Usher syndrome was the more frequent as it has been observed in 41% of the reported syndromic GCC cases. Finally, our analysis showed that HL genetics testing and research in the GCC region took advantage of the next generation sequencing (NGS)-based techniques, as approximately 58% of reported variants were identified using this technology.

Consanguineous marriage and its relevance to divorce, polygyny and survival of marriage: evidence from a population-based analysis in Jordan

BACKGROUND

Consanguinity has been extensively studied in the context of its negative health outcomes for offspring and socio-demographic factors, but little evidence-based research has been done on its potential social benefits.

AIM

To examine the association between consanguineous marriage and the risk of divorce or separation, polygyny, and survival of marriage in Jordan.

SUBJECTS AND METHODS

Data were obtained from the 2018 Jordan Population and Family Health Survey, covering a nationally representative sample of ever-married women of reproductive age. Descriptive statistics, multiple logistic regression, and survival analysis techniques were used for data analysis.

RESULTS

The prevalence of consanguineous marriage was found to be 27.5% in Jordan in 2018, while the prevalences of polygyny and divorced/separated rates were 4.4% and 4.7%, respectively. Both consanguineous and polygyny rates showed declining trends, but divorce/separation rate showed an increasing trend. Compared to non-consanguineous marriages, the risk of divorce/separation and polygyny were found to be lower among women with consanguineous marriage, while the survival of marriages was found to be higher for consanguineous marriages than for non-consanguineous marriages.

CONCLUSIONS

Findings revealed that consanguinity has some social benefits as it plays protective roles against divorce or separation, polygyny and enhances the survival of marriages.

Shared breastfeeding & other early multiple sclerosis risk factors: A case-control study

BACKGROUND

Multiple sclerosis (MS) is a chronic inflammatory autoimmune disease. Etiology is thought to be multifactorial with genetic and environmental factors interplay. Our objective in this study is to evaluate culture specific and other early life risk factors for MS. We examined the association between MS and breastfeeding including shared breastfeeding, parental consanguinity, being born abroad or living abroad during childhood, prematurity, vaccination, tonsillectomy, rank among siblings, number of siblings, number of household members (HHM) at birth, and age first time joining school.

METHODS

This is an age and sex matched case-control study that was conducted in Riyadh, Kingdom of Saudi Arabia (KSA). We enrolled 300 cases and 601 controls. A structured questionnaire about demographics, consanguinity and potential environmental factors was answered by participants. Data was analyzed using logistic regression adjusting for covariates occurring later in life such as waterpipe smoking and performing Hajj.

RESULTS

About two thirds of the cases and the controls were females. Mean age was 34.8 (9.2) for the cases and 33.6 (10.6) for the controls. We found that shared breastfeeding (OR=0.58; 95% CI, 0.35-0.96, p = 0.033), and older age first joining school (OR=0.83; 95% CI, 0.73-0.94, p = 0.005) were associated with decrease risk of MS. While longer duration of breastfeeding by biological mother (OR=1.03; 95% CI, 1.01-1.04, p = 0.001), rank among siblings of ≥6 (OR=1.69; 95% CI, 1.11-2.56, p = 0.014), and larger number of HHM at birth (OR=2.32; 95% CI, 1.64-3.28, p = 0.001) were associated with increased risk. Patients with MS were less likely to receive formula with breastfeeding than controls (OR=0.72; 95% CI, 0.51-0.99, p = 0.046). No association was found with breastfeeding by biological mother, number of siblings, prematurity, being born abroad or living abroad during childhood, vaccination, consanguinity, or tonsillectomy.

CONCLUSION

The findings of this case-control study add to the accumulating evidence that early life factors could modify the risk of developing MS. Among these, novel associations with shared breastfeeding and number of HHM at birth are suggested. Future studies are needed to verify the observed results.

Demographic and clinical characteristics of familial and sporadic multiple sclerosis: A single center exploratory study from Abu Dhabi

Demographic and clinical characteristics of Familial Multiple Sclerosis (FMS) have not been fully investigated yet in Abu Dhabi. The aim of this single center exploratory study was to investigate demographic and clinical characteristics of FMS compared to sporadic MS (SMS) in Abu Dhabi. A chart review single center study was conducted in 98 patients with MS. Group comparisons were performed using Mann-Whitney and Chi-Square tests as appropriate. A p < 0.05 was considered statistically significant. 24.5% were patients with FMS and 83% were Emirates. No significant differences in demographic and clinical characteristics were found between patients with FMS and SMS in overall all MS patients and in the Emirati group analyzed alone. Patients with FMS did not differ in demographic and clinical characteristics compared to patients with SMS. Further prospective studies are needed to elucidate environmental and genetic risk factors contributing to FMS in the Emirati population.

Consanguinity: A blessing or menace at population level?

Consanguinity has highly complex and multifaceted aspects with sociocultural as well as biological debates on its pros and cons. The biological upshot of consanguinity includes the increased homozygosity, which results in manifold increased risk of genetic disorders at family and population levels. On the other hand, in addition to social, cultural, political, and economic benefits, consanguineous marriages have biological advantages at the population level. The consequence of consanguineous marriages is an upsurge in the number of homozygous diseased individuals with fewer chances of mating and reduced chances of survival, therefore evolutionarily confining the transmission of disease alleles to future generations and encouraging its elimination from a population. Protective effects of consanguinity have also been observed in a few diseases in different populations. Although attractive for many reasons, nonconsanguineous marriages will cause risk alleles to spread throughout the population, making most individuals carriers, and ultimately will resume the production of recessive diseases in subsequent generations. Although consanguinity, from an evolutionary point of view, is beneficial at the population level, it increases the risk of diseases in the very next generation. Presently, there is no treatment for most of the genetic disorders; we cannot opt for consanguinity for long-term benefits. Nonconsanguineous marriages are a better strategy by which we may delay disease manifestation for some generations until science offers a viable solution.

Sociodemographic, environmental and lifestyle risk factors for multiple sclerosis development in the Western region of Saudi Arabia. A matched case control study

Objectives:

To examine the association of exposure to sociodemographic, environmental, and lifestyle risk factors during adolescence with the development of multiple sclerosis (MS).

Methods:

We conducted a case-control study between October 2017 and January 2018 at King Fahd General Hospital (KFH) in Madinah, Saudi Arabia. Data were collected by direct physician-subject interviews. We utilized a questionnaire modified from the environmental risk factors in multiple sclerosis questionnaire (EnvIMS-Q). Chi-square tests were used to examine associations of selected risk factors with the development of MS, a p-value of <0.05 was considered significant.

Results:

A total of 80 cases and 160 controls were enrolled into the study. Smoking during adolescence significantly increased the risk of MS, with an adjusted odds ratio (AOR) of 4.165, and a 95% confidence interval (CI) of 1.449-11.974. Large body size, assessed using a figure rating scale, also increased the risk of MS (AOR=8.970, 95% CI=1.032-77.983), as well as a history of measles infection (AOR=3.758, 95% CI=1.455-9.706). Furthermore, exposure to sunlight during the weekend for more than 4 hours/day decreased the risk of MS (AOR=0.063, 95% CI=0.006-0.654), so did the consumption of fish for more than once per week (AOR=0.206, 95% CI=0.055-0.773).

Conclusion:

The risk of developing MS is significantly increased by exposure during adolescence to smoking, a history of measles infection, and large body size (obesity).