Consanguinity and inflammatory bowel diseases: is there a relation?

Genetic and Epigenetic Etiology of Inflammatory Bowel Disease: An Update

Inflammatory bowel disease (IBD) is a chronic disease with periods of exacerbation and remission of the disease. The etiology of IBD is not fully understood. Many studies point to the presence of genetic, immunological, environmental, and microbiological factors and the interactions between them in the occurrence of IBD. The review looks at genetic factors in the context of both IBD predisposition and pharmacogenetics.

Consanguinity and Positive Family History of Inflammatory Bowel Diseases in Children: A Multicenter Case–Control Study

Inflammatory bowel diseases (IBD), which comprise Crohn's disease (CD) and ulcerative colitis (UC), are rising trend in Saudi population. We aim to examine the association between consanguinity and family history and the risk of childhood IBD in Saudi children. A multicenter case–control study conducted in three tertiary hospitals in Jeddah and Riyadh, Saudi Arabia, during periods 2009 to 2021. Data about demographics, consanguinity, family history of IBD, and type of IBD were collected using a structured questionnaire. The same questionnaire was applied in matched case–control. Odds ratios (OR) and 95% confidence intervals (CI) were estimated using unconditional logistic regression analysis that was performed to compare both groups. The study population included 335 children: 167 IBD patients (49.9%) and 168 controls (50.1%). Of these IBD, 93 patients (56%) were CD and 74 patients (44%) were UC. Most of participants were females (72.1%) and their age more than 10 years (51.5%). There was first-degree consanguinity in 66 IBD patients (49.6%). No significant difference in first-degree consanguinity between cases and controls was noted (49.6% in cases vs. 50.4% in controls; OR = 1.02; 95% CI = 0.66–1.57). The consanguinity showed a more significant association with CD than UC (p < 0.05). Family history of IBD (father, siblings, and grandparents) as risk factors for IBD was identified: paternal history of IBD (OR = 0.25, 95% CI = 0.08–0.76), siblings' history of IBD (OR = 2.16, 95% CI = 1.92–2.43), and grandparent's history of IBD (OR = 0.22, 95% CI = 0.07–0.65). Family history of IBD showed a more significant association with CD than UC (p < 0.05). Consanguinity is strongly associated with IBD with more significant association with CD than UC and may possibly explain IBD rise in Saudi Arabia. The greatest risk of family history of IBD is in first-degree relatives, especially in siblings' rather than parents and grandparents.

Genetic analysis of four consanguineous multiplex families with inflammatory bowel disease

BACKGROUND

Family studies support a genetic predisposition to inflammatory bowel diseases (IBD), but known genetic variants only partially explain the disease heritability. Families with multiple affected individuals potentially harbour rare and high-impact causal variants. Long regions of homozygosity due to recent inbreeding may increase the risk of individuals bearing homozygous loss-of-function variants. This study aimed to identify rare and homozygous genetic variants contributing to IBD.

METHODS

Four families with known consanguinity and multiple cases of IBD were recruited. In a family-specific analysis, we utilised homozygosity mapping complemented by whole-exome sequencing.

RESULTS

We detected a single region of homozygosity shared by Crohn's disease cases from a family of Druze ancestry, spanning 2.6 Mb containing the NOD2 gene. Whole-exome sequencing did not identify any potentially damaging variants within the region, suggesting that non-coding variation may be involved. In addition, affected individuals in the families harboured several rare and potentially damaging homozygous variants in genes with a role in autophagy and innate immunity including LRRK1, WHAMM, DENND3, and C5.

CONCLUSION

This study examined the potential contribution of rare, high-impact homozygous variants in consanguineous families with IBD. While the analysis was not designed to achieve statistical significance, our findings highlight genes or loci that warrant further research. Non-coding variants affecting NOD2 may be of importance in Druze patients with Crohn's disease.

Incidence, Prevalence, and Clinical Epidemiology of Inflammatory Bowel Disease in the Arab World: A Systematic Review and Meta-Analysis

Objectives

Despite the recent findings of the rising incidence of inflammatory bowel disease (IBD) in Arab countries, there are limited data on the characteristics of IBD patients and the disease course in the Arab world. This systematic review aimed to investigate the incidence and epidemiology of IBD in the Arab world.

Material and Methods

We conducted a systematic literature review that utilized a comprehensive search of PubMed, Cochrane Central, SCOPUS, Google Scholar, and Web of Science from their inception till August 2020. We included cross-sectional, prospective, and retrospective studies that examined the prevalence and/or epidemiological characteristics of IBD in Arab countries.

Results

A total of 16 studies that examined IBD in Saudi Arabia, Egypt, Kuwait, the United Arab Emirates, Bahrain, Lebanon, and Oman were included. Generally, the included studies covered the period from the early 1990s to the late 2010s. A total of 1,627 ulcerative colitis (UC) patients and 1,588 Crohn's disease (CD) patients were included in this systematic review. The mean age at diagnosis ranged from 24.13 to 43.6 years in adult cases and from 4.5 to 16 years in pediatric cases. In most of the included studies, the majority of patients were male. The quantitative analysis revealed a pooled incidence rate of 2.33 (95% confidence interval [CI] 1.2-3.4) per 100,000 persons per year for UC in the Arab world. Likewise, the pooled incidence rate for CD in the Arab world was 1.46 (95% CI 1.03-1.89) per 100,000 persons per year.

Conclusion

There is a growing incidence of IBD in the Arab world, while IBD patients from Arab countries may present with some different characteristics, compared to their counterparts in Europe.

Environmental exposures and the risk of inflammatory bowel disease: a case-control study from Saudi Arabia

BACKGROUND AND AIMS

Environmental exposures play a key role in inflammatory bowel disease pathogenesis. The incidence of IBD has increased in the Arabic Peninsula with a disease phenotype that seems to differ from that of Western countries. We aimed to examine the association between environmental exposures and the risk of IBD in Saudi Arabia.

PATIENTS AND METHODS

We performed a case-control study comparing Saudi individuals with confirmed IBD and healthy controls. All subjects completed a detailed questionnaire that included data on demographics, clinical characteristics, childhood exposures, socioeconomic exposures, and parent factors. Associations between risk factors and inflammatory bowel disease were investigated through univariate and multivariate regression analysis.

RESULTS

The analysis included 82 patients and 160 controls. According to multiple logistic regression analysis, holding a University/Master degree education level or a PhD degree reduced the risk of inflammatory bowel disease by 10-fold (odds ratio = 0.1, confidence interval = 0.1-0.3), receiving seven vaccines or more during childhood increased the risk of developing inflammatory bowel disease by nine-fold (odds ratio = 9.2, confidence interval = 2.9-29.4) and maternal use of oral contraceptives pills increased the risk by 11-fold (odds ratio = 11.4, confidence interval = 3.3-39.3).

CONCLUSION

Inflammatory bowel disease occurrence was independently associated with education level, number of childhood vaccination, and maternal use of oral contraceptives pills in this population of inflammatory bowel disease patients. This is the first study examining environmental exposures as risk factors for inflammatory bowel disease in Saudi Arabia.

Regional variation of pediatric inflammatory bowel disease in Saudi Arabia: Results from a multicenter study

BACKGROUND

Incidence and severity variations of inflammatory bowel disease (IBD) have been reported from Western populations between continents and regions of the same countries. However, no data were available from other countries.

AIM

To investigate the regional differences in the IBD profiles of pediatric patients from the Kingdom of Saudi Arabia.

METHODS

Data from a national multicenter IBD study were used. The incidence, time trend, and clinical presentation of Crohn’s disease (CD) and ulcerative colitis (UC) in the Central region (CR), Western region (WR), and Eastern region (ER) were analyzed and compared. Statistical analysis included Poisson regression analysis for incidence variation and Chi-square test for demographic and clinical parameters. A P < 0.05 was considered significant.

RESULTS

The prevalence of positive family history was lower in children with CD from the ER than the CR or the WR. Consanguinity rate was higher in children with CD and UC from the CR and the ER, respectively. The incidences and time trends of CD and UC were not significantly different between regions. In the ER, a significantly higher percentage of children with CD presented with abdominal pain (P < 0.001), blood in stools (P = 0.048), stricturing or penetrating disease (P = 0.029), higher erythrocyte sedimentation rate (P < 0.001), higher C-reactive protein (P < 0.001), higher anemia (P = 0.017), and lower albumin level (P = 0.014). For children with UC from the ER, a significantly higher percentage presented with anemia (P = 0.006) and a lower percentage with pancolitis (P < 0.001).

CONCLUSION

The most important finding is the identification of significantly more severe presentation of CD in the ER of the Kingdom of Saudi Arabia. Prospective studies are needed to explain such variations.

Epidemiology, disease burden, and treatment challenges of ulcerative colitis in Africa and the Middle East

Ulcerative colitis is an idiopathic, chronic, inflammatory bowel disorder characterized by an unpredictable course of alternating cycles of relapse and remission. Traditionally viewed as a disease of Western countries, the prevalence of ulcerative colitis is reported to be increasing in the developing world. In these regions, there is the potential to further explore the etiology of the disease, mainly through genetic studies. With this in mind, we consider available data relating to the epidemiology, clinical manifestations, and disease course of ulcerative colitis in Africa and the Middle East. Current treatment approaches in these countries are also reviewed and discussed in the context of new, small molecule, orally administered therapies. Areas covered: Available data on the epidemiology, clinical manifestations, and risk factors of ulcerative colitis in Africa and the Middle East are reviewed using a PubMed database search. Expert commentary: Epidemiologic studies from African and Middle Eastern countries suggest disease trends similar to the West, and an important health and economic burden. The management of ulcerative colitis within these developing countries is challenging, with the need to improve early diagnosis, access to healthcare, and patient education, along with facilitation of access to treatment options and improvement of medication adherence.

Mutations in Interleukin-10 Receptor and Clinical Phenotypes in Patients with Very Early Onset Inflammatory Bowel Disease: A Chinese VEO-IBD Collaboration Group Survey

BACKGROUND

Interleukin-10 (IL10) signaling plays an important role in the pathogenesis of very early onset inflammatory bowel disease (VEO-IBD) in children. However, little is known about the role of the IL10 axis in children with VEO-IBD in China.

METHODS

The Chinese VEO-IBD Collaboration Group was created to collect clinical and genetic data from patients deficient in IL10 and the IL10 receptor. High-throughput sequencing was performed to identify mutations in these genes.

RESULTS

We identified 32 compound heterozygous mutations and 9 homozygous mutations in IL10 receptor subunit alpha and 1 homozygous mutation in IL10 receptor subunit beta. Among these mutations, 10 novel mutations were identified, and 6 pathogenic mutations had been previously described. In patients with IL10 receptor subunit alpha mutations, c.301C>T (p.R101RW) and c.537 G>A (p.T179T) were the most common mutations. For 88.1% of the patients, the initial symptom was diarrhea, with a time of onset of 10.4 ± 8.0 days. Oral ulcers were the first symptom in 23.8% of the patients, with a time of onset of 9.7 ± 2.8 days. Extraintestinal manifestations included perianal abscesses (22/42), perianal fistulas (23/42), oral ulcers (20/42), and recurrent eczema (15/42). Twelve patients underwent enterostomy. These patients also had lower average Z scores in height-for-age and weight-for-age. Various treatment strategies were used, including fecal microbiota transplantation; however, only hematopoietic stem cell transplantation was efficacious.

CONCLUSIONS

This study identified genotypes and phenotypes of Chinese VEO-IBD infants with IL10 receptor mutations. Our study expands the current knowledge on the involvement of the IL10 axis in patients with VEO-IBD.

A cross-sectional survey of multi-generation inflammatory bowel disease consanguinity and its relationship with disease onset

Background\Aim: Consanguinity influences the phenotypic variations of some hereditary and immune-mediated disorders, including inflammatory bowel disease. This study estimated the prevalence of consanguinity among the ancestors of patients with inflammatory bowel disease and examined the effect of various consanguinity levels on inflammatory bowel disease onset.

PATIENTS AND METHODS

Patients with inflammatory bowel disease who were seen at two gastroenterology outpatient clinics were consecutively recruited and surveyed for demographics, disease onset, and presence of ancestral consanguinity within three generations. The prevalence of different consanguinity levels was calculated. The association between age at inflammatory bowel disease onset and consanguinity was examined.

RESULTS

Two hundred seventeen patients were recruited. The mean age, mean age at diagnosis, and mean illness duration were 32.9 ± 13.4, 18.6 ± 11.5, and 8.6 ± 7.7 years, respectively. Of the cohort, 53.5% were women, and 74.2% were native Saudis. Cigarette smoking was reported in 17.1%; 51% had Crohn's disease, while the remaining patients had ulcerative colitis. A family history of inflammatory bowel disease was reported in 29.5% of patients; consanguinity within three generations was reported in 57.6%. Consanguinity in more than one generation was reported in 38.7%; 17.5% had consanguinity in three consecutive generations. There was no association between inflammatory bowel disease onset and multi-generation consanguinity, but there was an association with disease subtype in favor of ulcerative colitis (b coefficient = 7.1 [95% confidence interval = 4.1, 10]).

CONCLUSIONS

Consanguinity is extremely common among Saudi patients with inflammatory bowel disease but does not seem to influence age at disease onset. Genetic studies are needed to further clarify the effect of consanguinity on disease behavior.

Clinical Pattern of Early-Onset Inflammatory Bowel Disease in Saudi Arabia: A Multicenter National Study

BACKGROUND

The objectives of this multicenter national study were to compare the clinical phenotype of early-onset inflammatory bowel disease (IBD) (EO-IBD) with IBD in older children and to examine whether there is any variability in consanguinity rate and familial aggregation in EO-IBD compared with later onset IBD.

METHODS

A retrospective analysis was performed on children aged 0 to 14 years with IBD in 17 centers located in geographically distinct regions in Saudi Arabia, from 2003 to 2012. Data of patients with EO-IBD (0 to <6 yrs) were compared with those with later onset IBD (6-14 yrs). Moreover, we evaluated differences in clinical pattern of infantile or toddler onset IBD subgroup (0-3 yr) as compared with those presenting in older children.

RESULTS

Of 352 IBD patients identified during the 10-year study period, 76 children (21.6%) younger than 6 years were diagnosed with IBD. Among the Crohn's disease (CD) group, infantile or toddler onset CD subgroup showed a more frequent isolated colonic involvement (L2) than later-onset group (57% versus 20%; P = 0.002). Positive family history was significantly more common in the infantile or toddler onset ulcerative colitis subgroup (29.4% versus 4.2% in later onset ulcerative colitis; P < 0.0001). The consanguinity rate was significantly higher in the infantile or toddler onset CD subgroup as compared with later onset CD group (57.1% versus 25.3%; P = 0.04).

CONCLUSIONS

In conclusion, EO-IBD exhibits a unique clinical phenotype with a strikingly higher familial aggregation in early-onset ulcerative colitis. Our data suggest a significant genetic impact on the onset of CD in the very young children.

Inflammatory bowel disease in Turkish children

BACKGROUND

This study was undertaken to evaluate demographics, clinical manifestations, laboratory findings and outcomes of children with inflammatory bowel disease (IBD) in Turkey.

METHODS

We analyzed the medical records of 127 children diagnosed with IBD (under 18 years old) between January 2004 and January 2012 in 8 pediatric gastroenterology centers.

RESULTS

Of the 127 patients, 90 (70.9%) suffered from ulcerative colitis (UC), 29 (22.8%) from Crohn's disease (CD), and 8 (6.3%) from IBD unclassified. The mean age of the 127 patients was 11.6 ± 4.1 years, and 11.8% of the patients were below 5 years old. Of the patients, 49.6% were male, and males were more predominant in patients with CD than in those with UC (72.4% vs. 42.2%, P = 0.008; a male/female ratio of 2.62 in CD, P = 0.0016). Approximately one fifth of the patients had extra-intestinal manifestations and 13.3% of the patients had associated diseases. Extraintestinal manifestations and associated diseases were more common in early onset disease [P = 0.017, odds ratio (OR) = 4.02; P = 0.03, OR = 4.1]. Of the patients, 15% had normal laboratory parameters including anemia, high platelet count, hypoalbuminemia, hypoferritinemia, and high sedimentation rate. Area under receiver operation characteristics was used to predict pancolitis in patients with UC. The values of C-reactive protein, sedimentation rate and pediatric ulcerative colitis activity were 0.61 (P = 0.06), 0.66 (P = 0.01) and 0.76 (P = 0.0001), respectively. Four (4.4%) patients with UC underwent colectomy, and finally two (1.5%, 95% confidence interval: 0-3.7%) patients died from primary disease or complications.

CONCLUSIONS

IBD is an increasing clinical entity in Turkey. Features of IBD are similar to those in other populations, but prospective multicenter studies are needed to analyze the true incidence of IBD in Turkish children.

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.