Preliminary evidence for genetic anticipation in Crohn's disease

A new face of old cells: An overview about the role of senescence and telomeres in inflammatory bowel diseases

Cellular senescence is a pivotal factor contributing to aging and the pathophysiology of age-related diseases. Despite the presence of inflammation and abnormal immune system function in both inflammatory bowel diseases (IBD) and senescence, the relationship between the two remains largely unexplored. Therefore, our study aimed to investigate the intricate connection between cellular senescence, telomeres, and IBD. The review highlights the presence of senescence markers, particularly p16 and p21, in IBD patients, suggesting their potential association with disease progression and mucosal inflammation. We emphasize the critical role of macrophages in eliminating senescent cells and how disturbance in effective clearance may contribute to persistent senescence and inflammation in IBD. Additionally, we shed light on the involvement of telomeres in IBD, as their dysfunction impairs enterocyte function and disrupts colonic barrier integrity, potentially exacerbating the pathogenesis of the disease. Targeting senescence and telomere dysfunctions holds promise for the development of innovative therapeutic approaches to mitigate intestinal inflammation and alleviate symptoms in IBD patients. By unraveling the precise role of senescence in IBD, we can pave the way for the discovery of novel therapeutic interventions that effectively address the underlying mechanisms of intestinal inflammation, offering hope for improved management and treatment of IBD patients.

Role of telomere shortening in anticipation of inflammatory bowel disease

BACKGROUND

The existence of genetic anticipation has been long disputed in inflammatory bowel disease (IBD) in the absence of the explanatory mechanism.

AIM

To determine whether it was predictive of genetic anticipation, we evaluated telomere length in IBD. We hypothesized that multiplex IBD families exhibit a genetic defect impacting telomere maintenance mechanisms.

METHODS

We studied three IBD families with multiple affected members in three successive generations. We determined telomere length (TL) in lymphocytes and granulocytes from peripheral blood of the affected members using flow cytometry and fluorescence in-situ hybridization (flow FISH). We also performed whole exome sequencing in the blood of all available family members and used PhenoDB to identify potential candidate gene variants with recessive or dominant modes of inheritance.

RESULTS

Out of twenty-four patients of European descent selected to participate in the study, eleven patients, eight parent-child pairs affected by IBD, were included in the genetic anticipation analysis. Median difference in age at diagnosis between two successive generations was 16.5 years, with earlier age at onset in the younger generations. In most of the affected members, the disease harbored similar gastrointestinal and extraintestinal involvement but was more aggressive among the younger generations. TL was not associated with earlier age at onset or more severe disease in members of successive generations affected by IBD. NOD2 gene mutations were present in the Crohn’s disease patients of one family. However, no gene variants were identified as potential candidates for inheritance.

CONCLUSION

Telomere shortening appears unlikely to be involved in mechanisms of possible genetic anticipation in IBD. Further studies using a larger sample size are required to confirm or refute our findings.

Familial aggregation of inflammatory bowel disease in India: prevalence, risks and impact on disease behavior

Background/Aims

Information about familial aggregation of inflammatory bowel disease (IBD) in Asia is limited. We aimed to analyze the prevalence and risk of familial IBD in an Indian cohort and compare familial and sporadic cases.

Methods

Familial IBD cases were identified from a large prospectively maintained IBD registry. The prevalence of IBD in first- and seconddegree relatives of index cases was evaluated. The disease behavior was compared to that of sporadic cases.

Results

Total 3,553 patients (ulcerative colitis [UC], 2,053; Crohn’s disease [CD], 1,500) were included. Familial IBD was noted in 4.13% of CD and 4.34% of UC patients. Family history was commoner in pediatric group (< 18 years) (P= 0.0002; odds ratio [OR], 2.8; 95% confidence interval [CI], 1.6–4.8). Majority had paternal transmission (UC, 67.42%; CD, 70.97%). Concordance of disease type was higher in UC (79.7%) compared to CD (37.1%). Familial IBD was associated with higher cumulative relapse rate (CD, P< 0.001; UC, P< 0.001), higher cumulative rate of surgery (CD, P< 0.001; UC, P< 0.001) and higher rate of biologic use (CD, P= 0.010; UC, P= 0.015). Pan-colitis was higher in familial UC (P= 0.003; OR, 1.935; 95% CI, 1.248–3.000). Fistulizing disease was commoner in familial CD (P= 0.041; OR, 2.044; 95% CI, 1.030–4.056).

Conclusions

The prevalence of familial IBD in India appears comparable to rest of Asia but lower than the West. It is associated with a younger age of onset, higher incidence of pan-colitis in UC and fistulizing complications in CD. Familial IBD has higher cumulative relapse, surgery and biologic use rates. Hence, family history of IBD could have important prognostic implications.

Change in Prevalence of Family History During Long-term Follow-up of Patients With Pediatric-onset Inflammatory Bowel Disease

OBJECTIVES

The aim of the study was to prospectively study changes in prevalence of positive family history (FH+) in pediatric-onset inflammatory bowel disease (IBD) in contrast to previously published cross-sectional data.

METHODS

An observational cohort study was performed using a prospective pediatric-onset IBD database including 485 patients with disease duration ≥10 years as of December 2016. Proband characteristics and FH+ were obtained at diagnosis and subsequently from the database, medical records, and follow-up telephone interviews in 2006 and 2016.

RESULTS

Updated 2016 information was obtained from 322 (66%) patients and included in analysis with median follow-up of 18 years (interquartile range 14, 26). Prevalence of FH+ increased from 13.7% at diagnosis to 26.6% at 20 years for first-degree relatives and from 38.5% to 52.2% for all relatives. At 20-year follow-up, an additional 10.0% of probands had a sibling, 6.1% had a parent, 1.9% had a grandparent, and 4.5% had a cousin diagnosed with IBD. FH+ at diagnosis was associated with greater risk for additional FH+ at 20 years (43% vs 22%, P < 0.001). Non-Jewish Caucasians had significantly lower risk of a FH+ compared to Jewish Caucasians (P = 0.002), but similar risk to African Americans (P = 0.55). FH+ at diagnosis was not associated with disease type (P = 0.33) or age at diagnosis (P = 0.24).

CONCLUSIONS

This prospective study documents changes in family history of IBD in pediatric-onset IBD patients over time. Prevalence of FH+ increased for first-degree and all relatives at 20 years by 12.9% and 13.7%, respectively. FH+ at diagnosis was associated with a 2-fold greater likelihood of subsequent FH+ at 20 years.

Trends in the epidemiology of inflammatory bowel disease among Jewish Israeli adolescents: a population-based study

BACKGROUND

The incidence and prevalence trends of inflammatory bowel disease (IBD) vary between developed and developing countries.

AIM

To investigate the prevalence and associated sociodemographic factors of IBD in Israeli Jewish adolescents METHODS: The files of the army medical corps were reviewed for adolescents recruited in 2002-2016 with confirmed IBD. Covariate data included birth date, patient and parental country of birth, number of children in the household, age at diagnosis, and socioeconomic status. Findings were compared with the remaining recruits without IBD.

RESULTS

Of the 1,144,213 adolescents recruited, 2372 (0.2%) had IBD (Crohn's disease, 68%). Median age of the cohort was 17.1 years (interquartile range, 16.9-17.3). Over the study period, the annual point prevalence per 100,000 examinees significantly increased: total IBD, 58 to 373; Crohn's disease, 42 to 425; ulcerative colitis, 16 to 128. Mean age at IBD diagnosis decreased from 15.0 ± 2.8 years in 2002-2008 to 14.3 ± 3.1 years in 2009-2016 (P < 0.0001). Significance was maintained on separate analyses of Crohn's disease and ulcerative colitis. Both diseases were significantly less prevalent in subjects from families with at least one parent born in a developing country and ≥3 children. There was a significant association of lower socioeconomic status with lower prevalence of Crohn's disease (odds ratio 0.41, 95% confidence interval, 0.31-0.54) and ulcerative colitis (odds ratio 0.25, 95% confidence interval, 0.15-0.42).

CONCLUSIONS

The point prevalence of Crohn's disease and ulcerative colitis in Israeli Jewish adolescents increased six-fold and eight-fold, respectively, over 15 years along with a decrease in age at diagnosis.

The Rise and Fall and Rise of Linkage Analysis as a Technique for Finding and Characterizing Inherited Influences on Disease Expression

For many years, family-based studies using linkage analysis represented the primary approach for identifying disease genes. This strategy is responsible for the identification of the greatest number of genes proven to cause human disease. However, technical advancements in next generation sequencing and high throughput genotyping, coupled with the apparent simplicity of association testing, led to the rejection of family-based studies and of linkage analysis. At present, genetic association methods, using case-control comparisons, have become the exclusive approach for detecting disease-related genes, particularly those underlying common, complex diseases. In this chapter, we present a historical overview of linkage analysis, including a description of how the approach works, as well as its strengths and weaknesses. We discuss how the transition from family-based studies to population comparison association studies led to a critical loss of information with respect to genetic etiology and inheritance, and we present historical and contemporary examples of linkage analysis "success stories" in identifying genes contributing to the development of human disease. Currently, linkage analysis is re-emerging as a useful approach for identifying disease genes, determining genetic parameters, and resolving genetic heterogeneity. We posit that the combination of linkage analysis, association testing, and high throughput sequencing provides a powerful approach for identifying disease-causing genes.

Familial and ethnic risk in inflammatory bowel disease

Familial aggregation in inflammatory bowel disease (IBD) has been established for several decades, reflecting shared genetic and environmental susceptibility. A positive family history remains the strongest recognizable risk factor for the development of IBD and is reported in around 8-12% of IBD patients. Crohn’s disease shows a more frequent familial pattern than ulcerative colitis. The risk of developing IBD in first-degree relatives of an affected proband is increased 4- to 8-fold. The risk for twins and children born from couples who both have IBD is also substantially higher; a cumulative effect of the number of family members affected has been described, with the highest incidence being described for families with three or more affected members. Herein, we review the available evidence regarding familial IBD, and briefly discuss the variation of IBD across different races and ethnicities, hoping to provide a useful update and a practical guide that can serve clinicians as a guide for counseling.

A rising incidence and poorer male outcomes characterise early onset paediatric inflammatory bowel disease

BACKGROUND

The incidence of paediatric inflammatory bowel disease diagnosed before age 10 years is reportedly increasing, but national data are limited.

AIM

To characterise the epidemiology, phenotype and clinical outcomes of children diagnosed with inflammatory bowel disease before age 10 years, and compare with data from children diagnosed aged 10-16 years.

METHODS

A review of all Irish cases of early onset inflammatory bowel disease (diagnosis <10 years, EO-IBD) presenting between January 2000 and December 2014 was undertaken and compared to a cohort of later onset paediatric inflammatory bowel disease patients (diagnosis between 10 and 16 years, LO-IBD). Diagnostic investigations, phenotype, treatments, and long-term clinical and surgical outcomes were analysed.

RESULTS

One hundred and ninety children (99 male) with EO-IBD were identified; 92 (48%) CD, 77 (41%) UC and 21 (11%) IBDU. The incidence of EO-IBD increased by 0.6 per 100 000 per year (0.8-3.2 per 100 000 per year), with a significant increase in UC by 0.06 per 100 000 per year (P=.02). Males with CD had more upper GI disease (L4a; 48% vs 21%; P=.007), more extensive disease distribution (L3±L4; 31% vs 11%; P=.05) and more severe disease activity at presentation (52% vs 31%; P=.05) than females. Fewer patients with early onset than later onset Crohn's disease had ileocolonic disease (L3; 10% vs 20%; P<.001). More relapses were observed in the first year post-diagnosis in early onset than later onset IBD (1.02 vs 0.5 mean relapses; P<.001).

CONCLUSIONS

EO-IBD is increasing in incidence. Males have more extensive and severe disease phenotypes, and younger patients have higher relapse rates than older children. Further research to explain these findings is warranted.

Inflammatory bowel disease

Scandinavian researchers have contributed to the present understanding of inflammatory bowel disease (IBD). Important epidemiological data and family risk factors have been reported from all the Nordic countries, original twin studies mainly from Denmark and Sweden, and relationships to cancer and surgery mostly from Sweden. In collaboration with the industry, development of medical compounds was for a long time in the front line of international research, and the Scandinavian countries participated in the clinical breakthrough of biologic treatment. At present, many Nordic centers are working in the forefront of IBD research. An increasing number of young investigators have entered the scene along with the extended distribution of University clinics and research laboratories in these countries. This presentation of IBD gives a brief overview in the fields of clinical epidemiology and molecular biology. Many areas are covered by International collaborations with partners from Nordic centers. IBD was a topic focused by the founders of Scandinavian Journal of Gastroenterology. After 50 years one may state that the journal's history reflects important pieces of scientific knowledge within these diseases. The early scope of Johannes Myren for IBD was shown through his work in the original World Association of Gastroenterology (OMG), and after 50 years we can clearly support the view that global perspectives in IBD are increasingly important.

Family history of inflammatory bowel disease among patients with ulcerative colitis: a systematic review and meta-analysis

BACKGROUND AND AIMS

Despite numerous shared susceptibility loci between Crohn's disease and ulcerative colitis, the prevalence of family history among ulcerative colitis patients is not well-established and considered to be less prevalent. A systemic review and meta-analysis were conducted to estimate the prevalence of family history of inflammatory bowel disease in ulcerative colitis patients, and its effect on disease outcomes.

METHODS

PubMED was searched to identify studies reporting the prevalence of family history of inflammatory bowel disease among ulcerative colitis patients. Definitions of family history, study type, and subtypes of family history prevalence were abstracted, as were disease outcomes including age at ulcerative colitis diagnosis, disease location, surgery and extraintestinal manifestations. Pooled prevalence estimates were calculated using random effects models.

RESULTS

Seventy-one studies (86,824 patients) were included. The prevalence of a family history of inflammatory bowel disease in ulcerative colitis patients was 12% (95% confidence interval [CI] 11 to 13%; range 0-39%). Family history of ulcerative colitis (9%; 22 studies) was more prevalent than Crohn's disease (2%; 18 studies). Patients younger than 18years of age at time of diagnosis had a greater family history of inflammatory bowel disease (prevalence 15%, 95% CI: 11-20%; 13 studies). There were no differences in disease location, need for surgery, or extraintestinal manifestations among those with a family history, although very few studies reported on these outcomes.

CONCLUSIONS

Overall, 12% of ulcerative colitis patients have a family history of inflammatory bowel disease, and were more likely to have a family history of ulcerative colitis than Crohn's disease. Pediatric-onset ulcerative colitis patients were more likely to have a family history of inflammatory bowel disease.

Association of linear growth impairment in pediatric Crohn's disease and a known height locus: a pilot study

The etiology of growth impairment in Crohn's disease (CD) has been inadequately explained by nutritional, hormonal, and/or disease-related factors, suggesting that genetics may be an additional contributor. The aim of this cross-sectional study was to investigate genetic variants associated with linear growth in pediatric-onset CD. We genotyped 951 subjects (317 CD patient-parent trios) for 64 polymorphisms within 14 CD-susceptibility and 23 stature-associated loci. Patient height-for-age Z-score < -1.64 was used to dichotomize probands into growth-impaired and nongrowth-impaired groups. The transmission disequilibrium test (TDT) was used to study association to growth impairment. There was a significant association between growth impairment in CD (height-for-age Z-score < -1.64) and a stature-related polymorphism in the dymeclin gene DYM (rs8099594) (OR = 3.2, CI [1.57-6.51], p = 0.0007). In addition, there was nominal over-transmission of two CD-susceptibility alleles, 10q21.1 intergenic region (rs10761659) and ATG16L1 (rs10210302), in growth-impaired CD children (OR = 2.36, CI [1.26-4.41] p = 0.0056 and OR = 2.45, CI [1.22-4.95] p = 0.0094, respectively). Our data indicate that genetic influences due to stature-associated and possibly CD risk alleles may predispose CD patients to alterations in linear growth. This is the first report of a link between a stature-associated locus and growth impairment in CD.

Familial aggregation and antimicrobial response dose-dependently affect the risk for Crohn's disease

BACKGROUND

An increased risk of Crohn's disease (CD) has been reported consistently in first-degree relatives of patients. Our aim was to test whether a combination of CD-associated genes involved in innate immunity and/or antibody responses to microbial antigens may be valuable in identifying healthy relatives at risk.

METHODS

We investigated 86 families from Belgium and northern France, 45 with at least 3 first-degree relatives with CD, 24 with a single case, and 17 control families without inflammatory bowel disease (IBD). The cohort consisted of 186 CD patients, 290 healthy relatives, and 142 controls (total 618). Genetic (NOD2, NOD1, TLR4, CARD8) and serologic markers (ASCA, ACMA, ALCA, ACCA, ASigmaMA, OmpC, CBir1, I2) were determined in all subjects. All Belgian families were prospectively followed up for 54 months.

RESULTS

In multiple-affected families, an increment of affected first-degree relatives and of positive antibodies were additive risks factors for CD (P < 0.0001), independent of NOD2 mutations. When comparing subjects from multiple-affected families, having 3 additional first-degree relatives with CD and 1 additional positive antibody increased the odds for CD to 9.19 (95% confidence interval [CI]: 4.07-20.80). After a follow-up of 54 months among all Belgian families, a total of 4 new diagnoses of IBD were confirmed in the multiple-affected families only, resulting in a 57-fold increase in incidence within multiple-affected families compared to the known incidence of IBD in our region.

CONCLUSIONS

We found an additive risk increment for CD in subjects from multicase families per additional affected relative and per additional positive antibody, independent of NOD2. Furthermore, a very high disease incidence was observed in these multiple-affected families.

Long-term health outcomes in pediatric inflammatory bowel disease: a population-based study

BACKGROUND

The long-term sequelae of inflammatory bowel disease (IBD) may differ between children and adults. We evaluated the health status of patients with pediatric onset of IBD and controls in early adulthood.

METHODS

A questionnaire on the current health status and disease history was mailed to patients with childhood onset IBD diagnosed during 1987-2003 in 2 university hospitals in Finland. Matched controls were randomly selected from the Population Register Centre.

RESULTS

A total of 368 (67%) of the 550 patients and 646 (37%) controls responded (median age 20 years). Ulcerative colitis (UC) was the most common primary diagnosis (58%) reclassified as Crohn's disease (CD) in 8.5%. Of the patients, 80% had been on glucocorticoids at some point (median duration of the disease 8.3 years). One-third of CD patients had undergone intestinal resection. In UC, total colectomy was common (24%). The frequency of joint diseases (5.4% versus 0.2%) and biliary duct diseases (2.7% versus 0.3%) was higher in patients than in controls (P < 0.001). Overall quality of life was decreased in the patients (mean score 5.7 versus 6.0 in controls, P < 0.001). Further, some impediment on adult height and weight was observed among male patients.

CONCLUSIONS

IBD in children may have a more aggressive disease course than in adults, since most pediatric patients need glucocorticoids, and abdominal surgery is frequent. At 8 years from diagnosis, most patients have active disease and quality of life is slightly lower than in the rest of the population.

The complexity and challenges of genetic counseling and testing for inflammatory bowel disease

Inflammatory bowel disease (IBD) is an umbrella term referring to two chronic idiopathic intestinal diseases: ulcerative colitis (UC) and Crohn's disease (CD). Both UC and CD are characterized by immune activation that leads to symptoms, but the location, severity and behavior of the inflammation varies among individuals and in characteristic ways between UC and CD. A majority of patients with IBD are diagnosed in young adulthood, but the response to therapy is variable and difficult to predict, with some patients demonstrating a prompt and effective remission while others have continuous symptoms that do not respond to existing medical options. Surgery remains a frequent and necessary occurrence among patients with IBD, but in UC it is considered curative, while in CD only temporizing. Clinical observations, epidemiological studies, and molecular genetics have provided strong evidence that both genetic and environmental factors are important determinants for disease susceptibility. In recent years, a number of genes have been identified that associate with CD and UC, although the clinical utility of these discoveries in patients or in susceptible family members has not been determined. Nonetheless, it is hoped that these fundamental advances in our understanding of IBD will lead to better therapies for patients and prevention strategies for those who are susceptible. Effective incorporation of clinical genetic testing for IBD into practice will require appropriate education and counseling.

Family and twin studies in inflammatory bowel disease

Studies examining the inheritance of inflammatory bowel disease (IBD) within different family groups have been the basis for recent molecular advances in the genetics of IBD. The derived heritability in Crohn’s disease (CD) is higher than in many other complex diseases. The risk of IBD is highest in first-degree relatives of a CD proband, but first-degree relatives of a proband suffering from ulcerative colitis (UC) and more distant relatives are also at increased risk. Disease concordance rates in IBD have been examined in multiplex families and in three large European twin studies.

IBD: a family affair

The recent molecular advances in the understanding of the genetics of inflammatory bowel disease (IBD) have their grounding in studies examining IBD within different family groups and populations. The risk of IBD is highest in first-degree relatives of an IBD proband but more distant relatives are also at increased risk. The risk is higher for relatives of a CD proband. The risks of developing IBD for 'high-risk' relatives might be as great as 1 in 3 but in general first-degree relatives have a 1 in 10-20 risk. Three recent systematic studies have identified a total of 326 European twin pairs to examine disease concordance rates. The derived heritability in Crohn's disease is greater than for many complex diseases and is currently under detailed examination. Strong concordance has been shown, in particular for disease type and disease location, in multiplex families and twin studies. More than 75% children are diagnosed with IBD at a younger age than their parents but true genetic anticipation appears unlikely.

Specificities of inflammatory bowel disease in childhood

In parallel with overall population trends, the incidence of paediatric ulcerative colitis (UC) has remained stable, whereas that of paediatric Crohn's disease (CD) has increased in recent decades. Still rare among preschool children, the incidence of both UC and CD rises steadily from middle childhood through adolescence. There is an unexplained preponderance of males with early-onset CD, and an equal gender distribution in paediatric UC. Observations on the familiality of paediatric inflammatory bowel disease (IBD) suggest that genetic susceptibility is particularly important to disease pathogenesis in young patients. In comparison to adult-onset disease, childhood UC is usually extensive but the anatomic localization of paediatric CD varies, as in adults. UC manifests uniformly as bloody diarrhea whereas the symptomatology of paediatric CD is much more diverse. Linear growth impairment frequently complicates chronic intestinal inflammation in paediatric CD. Key contributing factors have been defined; better immunomodulatory therapy and emerging biologic agents will potentially reduce its prevalence.

Age and family history at presentation of pediatric inflammatory bowel disease

OBJECTIVES

Young children are thought to be a unique subset of pediatric patients with inflammatory bowel disease (IBD). The authors' objective was to evaluate the differences in initial clinical presentation of young and older children with IBD and to determine whether a positive family history of IBD is associated with the age of presentation.

METHODS

The authors reviewed the records of all patients with new diagnoses of Crohn disease (CD) and ulcerative colitis (UC) who presented between July 1996 and July 1999. Initial evaluation included assessment of growth parameters and laboratory values (hemoglobin concentration, platelet count, erythrocyte sedimentation rate, and serum albumin). Inquiry regarding a family history of IBD was made in every patient.

RESULTS

There were 153 patients with new diagnoses (82 with CD and 71 with UC), with a mean age of 11.9 years (range, 16 months-18 years). The children with CD had a higher sedimentation rate and platelet count and a lower mean hemoglobin concentration and serum albumin at presentation than did children with UC. Body mass index (BMI) was significantly lower in patients with newly diagnosed CD than in those with UC. The only significant laboratory differences between patients younger than 11 years and those 11 years or older was a higher mean platelet count in patients with CD who were younger than 11 years. Of the younger patients with CD, 41.7% had a positive family history of IBD, which was significantly greater that that found in the older patients with CD.

CONCLUSIONS

Except for higher platelet counts, a lower BMI, and a higher frequency of positive family history in young children with CD, there were no significant differences in the presentation of young children with IBD compared with older children.

What are the major arguments in favour of the genetic susceptibility for inflammatory bowel disease?

Epidemiological data, notably concordance rates in twin pairs and familial aggregation, have provided strong evidence for the importance of the genetic contribution in inflammatory bowel diseases. Genome wide scanning has been remarkably successful in identifying a number of susceptibility loci. The identification of the IBD1 gene on chromosome 16 as NOD2/CARD15 definitely establishes that a significant proportion of Crohn's disease has an underlying genetic cause. In addition, our knowledge of the clinical impact of other genes in modelling disease phenotypes has increased in parallel. These results have led to great optimism that important clinical applications will result from genetic research in the near future.

Review article: maintenance treatment of Crohn's disease

The aetiology of Crohn's disease is unknown and therefore no curative treatments are available for the disease. The natural history of Crohn's disease is characterized by recurrent flare-ups of symptoms. Several drug treatments are effective in inducing clinical remission. However, no drug treatments are available in order to prevent clinical relapses, although several drug regimens may delay clinical flare-ups. Crohn's disease treatment for maintaining clinical remission needs to be tailored in relation to specific characteristics of each patient. The frequency of clinical relapse indeed shows marked variations in subgroups of patients, as the likelyhood of relapse is higher in patients in clinical remission for less than 6 months. Treatment strategies for maintaining remission may therefore differ among inactive patients. In chronically active, steroid-dependent or steroid-refractory Crohn's disease patients immunomodulatory drugs (azathioprine 2-2.5 mg/kg by mouth, 6-mercaptopurine 1-1.5 mg/kg by mouth, or methotrexate 15-25 mg/i.m./week) should be added to oral mesalazine (2.4 g/day), while in long-term inactive Crohn's disease patients mesalazine alone may be effective in delaying relapse. Recently, treatment with anti-tumour necrosis factor-alpha monoclonal antibodies (Infliximab or CDP571) has shown efficacy in delaying relapse in responsive patients. One other issue which needs to be considered before selecting drug treatments for maintaining remission in Crohn's disease, is that Crohn's disease activity is currently assessed on the basis of standard clinical scores which may not appropriately reflect the biological activity of the disease. Clinical remission as defined by standardized scores may include heterogeneous subgroups of patients showing different endoscopic and histological activity or persistence of activated immunocompetent cells within the gut. Several sub-clinical markers of relapse have indeed been reported in quiescent Crohn's disease, although their usefulness in clinical practice in currently uncertain.

Preliminary evidence of genetic anticipation in Graves' disease

Despite strong epidemiologic evidence in favor of a genetic component in the etiology of Graves' disease, few hereditary risk factors have been consistently identified. The term genetic anticipation denotes a decrease in the age of onset as disease is passed through generations. In the past 5 years, genetic anticipation has been described in immune-mediated diseases such as rheumatoid arthritis and chronic inflammatory bowel disease, and recently this phenomenon has been linked to unstable expanded trinucleotide repeat sequences in several diseases. If present in Graves' disease, anticipation could provide clues to its genetic etiology. The aim of the present study was to investigate whether genetic anticipation may occur in Graves' disease. Age at diagnosis and age at ascertainment were registered and compared in 33 same-gender parent-offspring pairs with Graves' disease from multiply affected families primarily ascertained for a genetic linkage study. The mean age at diagnosis was 46.6 years (range, 16-77) in the parents and 34.1 years (range, 16-44) in the children. The difference in the mean age at diagnosis between parents and their children was 12.5 years (95% confidence interval 3.0-21.9), p = 0.010. Children were younger than their parents at diagnosis in 25 of 33 pairs (76%). In 7 pairs (21%), the parent was diagnosed after the child according to the calendar years. Essentially similar results were obtained after controlling for gender and smoking habits. In conclusion, our data suggest that patients in the second affected generation seem to acquire their disease at an earlier time in life in familial cases of Graves' disease, indicating that genetic anticipation might occur.

Clinical features in familial cases of Crohn's disease and ulcerative colitis in Italy: a GISC study. Italian Study Group for the Disease of Colon and Rectum

OBJECTIVE

Previous studies have reported genetic anticipation, genomic imprinting, and phenotypic concordance of some clinical features in familial cases of Crohn's disease (CD) and ulcerative colitis (UC). The aim of our study was to investigate the phenotypic features of affected members in a large sample of CD and UC Italian families.

METHODS

In a multicenter study, CD and UC families were recruited. Affected members were questioned about date of birth, gender, age at onset of symptoms and at diagnosis, location and extension of disease, occurrence of extraintestinal manifestations, use of steroids and/or of immunosuppressive drugs, need for resective surgery, and number of relapses per year (< 1 yr or > or = 1 yr). Statistical analysis was performed with chi2, Fisher's, Mann-Whitney U, and binomial probability tests, when appropriate.

RESULTS

A total of 128 families with 270 affected members were studied: 35 were CD, 64 UC, and 29 mixed families (when UC and CD affected different members). In 99 of 128 families (77%), the diagnosis was concordant. In CD families, a high concordance for localization (46%), extraintestinal manifestations (67%), need for steroids (77%), need for immunosuppressive drugs (100%), need for surgery (29%), and relapse rate (36%) was found. In UC families, a high concordance for disease extension (33%), need for steroids (47%), and relapse rate (34%) was disclosed. A higher than expected concordance for ileal localization (p < 0.4) in CD families and extensive colitis (p < 0.05) in UC families was demonstrated. A generation difference of 15-20 yr in mean ages at onset of symptoms and at diagnosis was recorded. No features of more aggressive disease in subsequent generations and no differences in gender of transmitting parents and relatives were found.

CONCLUSIONS

Our study shows a high rate of concordance for diagnosis and clinical features in UC and, especially, CD families. The disease occurred 15-20 yr earlier than in previous generations without features of increased severity.

Recent advances in inflammatory bowel disease

The last decade has seen tremendous advances in our knowledge, which has led to genuine improvements in our understanding of the pathogenesis and management of inflammatory bowel disease (IBD). The combined power of cellular and molecular biology has begun to unveil the enigmas of IBD, and, consequently, substantial gains have been made in the treatment of IBD. Refinements in drug formulation have provided the ability to target distinct sites of delivery, while enhancing the safety and efficacy of older agents. Simultaneous progress in biotechnology has fostered the development of new agents that strategically target pivotal processes in disease pathogenesis. This article addresses our current understanding of the pathogenesis of IBD, including the latest developments in animal models and covers agents currently used in the treatment of IBD as well as emerging therapies.

Molecular genetics and Crohn's disease

This article reviews basic molecular genetics and summarizes recent work in the genetics of Crohn's disease. Family studies are summarized, and candidate genes are described. The current state of knowledge and the implications of possible inheritance of Crohn's disease for patient care are discussed.

A critical review of epidemiological studies in inflammatory bowel disease

This review addresses the difficulty in interpreting the results of epidemiological studies in IBD and in making meaningful comparisons between studies. Both ulcerative colitis and Crohn disease appear to be more common in some industrialized countries such as Scandinavia, United Kingdom, North America and less common in Central and Southern Europe, Asia and Africa. Given data showing an increased incidence of ulcerative colitis in the United Kingdom, it is crucial that more studies be conducted in developing countries. While the incidence of Crohn disease has increased strikingly in many areas, the incidence of ulcerative colitis has remained fairly stable in most. This could be due to the rising number of community-based studies, as well as the improved accuracy in diagnosing Crohn disease. Although, the incidence of IBD among Blacks in Africa is low, infection rates are high, life expectancy is lower than in developed countries. Data from the USA suggest that rates are similar in Afro-American and Caucasian populations. Rates for Jewish populations may be slightly higher than in non-Jewish populations but this also varies geographically. Careful attention to genetic, environmental, and socioeconomic factors must be accounted for in these studies. There is no strong evidence to support that IBD is more common in urban than in rural settings and migration towards more accessible health care has not been adequately addressed. Recent epidemiological studies suggest that mortality rates for IBD are similar to that of the general population for the majority of patients. However, older patients with IBD and newly diagnosed cases with severe diseases are at increased risk of dying. Epidemiological studies remain important in assisting with health policy planning and in hypothesis testing of etiological factors. As better diagnostic techniques become widely available and public health registries are increasingly used, it is possible that geographic differences will diminish. International collaborative studies will be better equipped to answer research questions addressing risk factors and disease natural history. We have summarized in Table V the essential criteria to conduct a sound epidemiological study, which would permit future testing of hypotheses among different populations.

Familial and sporadic inflammatory bowel disease: different entities?

The strongest risk factor for developing inflammatory bowel disease (IBD) is having a relative with the disease. Familial IBD may be one homogeneous subgroup, phenotypically different from sporadic IBD. Several observations support a role for familiarity in disease site and behavior, particularly in Crohn's disease (CD), but published findings do not all concur. Early disease onset is often found in children with IBD who have a parent with the disease. Genetic anticipation may explain this finding but other explanations and/or observational biasis are more likely. Location and type may differ between familial and sporadic CD cases: family studies report many cases involving both small bowel and colon, and few cases of colonic disease alone, although such features may be secondary to early age at onset. Most studies found no effect of positive family history on severity and course of CD. In ulcerative colitis (UC), phenotypic differences between familial and sporadic cases appear to be limited, but little data are available for analysis. No difference has been found between familial and sporadic IBD as far as disease markers such as pANCA, ASCA, or intestinal permeability are concerned. In conclusion, the only message available for clinical practice is that the relative risk of IBD in first-degree relatives is increased by a factor of 10-15 compared with the general population. Families should not receive genetic counseling/information about age at onset and disease severity.

Inflammatory bowel disease

Till about 3 decades ago, inflammatory bowel disease (IBD) was considered as non-existent in our country. However, since that time several reports of IBD, mainly ulcerative colitis have been published. More recently, Crohn's disease is also being reported from the country. This trend of UC appearing first in a population followed by CD also appears to be true in other developing nations. A substantial increase in the rates of CD over UC in the last few decades is reported from developed nations as well. Of the other epidemiological factors, an increased risk of CD and lower risk of UC in smokers is established in adults. However, it appears that smoking increases the risk of IBD in children. The etiology of IBD remains elusive. Within the triad of genetics, immunity and antigen responsible for the development of IBD, maximum advances have been made in the field of immune aberrations and this is being exploited to treat the disease. It is well established that IBD results from a disordered immune system in the gut, in response to an unidentified antigen in a predisposed individual. The immune response is enhanced and revolves around antigen-presenting cells, CD 4 T-lymphocytes and tumor necrosis factor alpha. CD results from an enhanced Th1 activity. The pathogenesis of UC is less clear but appears to be humoral. Advances in diagnostics include the availability of serology, ultrasound and nuclear scans, none of which have been tried in our setting where infectious diseases and tuberculosis is rampant. Growth failure and the importance of nutrition in IBD, especially CD, cannot be underemphasized. In many situations nutritional interventions have been used solely as a form of therapy for CD. Newer steroid molecules with minimal systemic effects are also being considered. Other treatment options highlighted are the use of immunosuppressive agents, biologic agents and role of surgery.

Problems in the identification of hereditary nonpolyposis colorectal cancer in two families with late development of full-blown clinical spectrum

The recognition of Hereditary Nonpolyposis Colorectal Cancer (HNPCC) remains difficult despite the most recent advancements of molecular biology and technology. We describe two families with early onset of cancer but no suspicion of hereditary tumors; during follow-up, both families developed a tumor spectrum highly suggestive of HNPCC, thus emphasizing the importance of family history for a proper identification of hereditary tumors or cancer aggregation. Microsatellite instability was negative in tumors from both families and, as expected, no germline mutations of the major DNA mismatch repair genes (MSH2 and MLH1) could be detected. Suspicion of the disease at the time of proband's lesion might have led to prevention, or early diagnosis, of at least three malignant tumors. We conclude that a possible genetic origin should always be suspected in individuals with early-onset neoplasms of the large bowel and probably of other organs such as the endometrium, small bowel, and urothelium, even when the initial pedigree does not show marked aggregation of cancers or vertical transmission.

Anticipation in inflammatory bowel disease: a phenomenon caused by an accumulation of confounders

Inflammatory bowel disease (IBD) has a definite genetic component as documented by epidemiological and linkage evidence. It shows an earlier onset of disease in children of affected patients than in their parents. This has lead to speculations about genetic anticipation in this disorder. 2,007 IBD patients with sporadic disease and 472 multiplex familial cases (including 103 affected parents and 99 children of affected patients) were evaluated with a multi-item questionnaire as part of a study of inflammatory bowel disease genetics. The Mann-Whitney U-test and the general linear model were used for analysis. Clinical characteristics such as presence of fistulae, stenoses, extraintestinal manifestations, and other parameters, which are related to the severity of the disease, were found to be similar between familial and sporadic cases of IBD (corrected P > or = 0.31 for all tests). The mean-age-of onset in children of affected patients was 19.4 years earlier than in their parents. However, the age of the parental cohort was significantly higher (27 years) and the diagnostic interval also longer (1.7 years). If these confounders are corrected in a general linear model, no significant difference is evident for the age-of-onset between the groups (P > or = 0.52). There is no evidence for genetic anticipation in inflammatory bowel disease. The absence of genetic anticipation is consistent with the clinical similarity of familial and sporadic inflammatory bowel disease. This finding justifies the primary genetic analysis of familial disease under the assumption that their genetic background will be representative for all presentations of IBD.

Assessing changes in ages at onset over successive generation: an application to breast cancer

Decreased age at onset in successive generations has been observed for a number of diseases. Two nonparametric matched and unmatched test statistics are proposed, taking into account not only current age or age at death for unaffected individuals and age at disease onset for affected individuals, but also possible correlations among family members. Both are asymptotically normal with readily estimated variances from the data. A simulation study is conducted to compare the proposed tests with the commonly used paired t-test and log-rank test. It has been shown that the proposed test statistics yield valid conclusions in assessing genetic anticipation under all situations considered. However, the paired t-test is valid only when the censoring distributions are comparable between two generations, whereas the log-rank test is valid when the correlation among family members is weak. As expected, the matched test is most powerful when the data are heterogeneous, and the unmatched and the log-rank tests are most powerful when the data are homogeneous and the correlation is weak. Lastly, a population-based family study of breast cancer conducted at the Fred Hutchinson Cancer Research Center is used for illustration of the proposed and the log-rank tests. The preliminary analysis suggests that there appears a decreased age at onset over the successive generations in breast cancer.

Genetics and inflammatory bowel disease

Genetic factors have a definite role in the etiology of inflammatory bowel disease (IBD). The mode of inheritance suggests a polygenic disease with the penetrance of the genetic factors being strongly influenced by the lifestyle of an industrialized society. Molecular techniques, which have become available through the progress of the human genome project, allowed a first series of linkage studies in pairs of affected siblings with IBD, which suggested multiple genomic susceptibility regions. These regions are still large, but considerable progress is being made toward the identification of actual disease genes. It is hoped that an understanding of the genetic etiology of IBD will lead to enhanced diagnostic procedures, more effective therapeutic interventions, and preventive strategies in the future.

Anticipation in Crohn's disease may be influenced by gender and ethnicity of the transmitting parent

OBJECTIVE

We sought to examine whether anticipation (an earlier age of onset in succeeding generations) is observed in Crohn's disease (CD) patients within the New York metropolitan area, and whether there are differences in the degree of anticipation with respect to gender and ethnicity of the affected parent.

METHODS

Sixty-one parent-child pairs both affected by CD were identified; about half of the pairs were of Ashkenazi Jewish descent. An additional 17 pairs of second-degree relatives with CD were also identified. The intergenerational difference in age at diagnosis (AAD) was used to perform regression analysis and the degree of anticipation among subsets of patients separated on the basis of gender and ethnicity of the transmitting parent was determined.

RESULTS

The AAD was consistently (90% of the time) lower in the younger member of the 61 parent-child pairs (35.3+/-1.6 yr vs 20.8+/-1.1 yr, p = 0.0001). Furthermore, the degree of anticipation was significantly greater for father-child pairs (20.6+/-3.2 yr) than for mother-child pairs (11.7+/-2.1 yr). However, when the patient population where the parent had an AAD of < 28 was analyzed separately, there was a lack of clear-cut evidence of anticipation in the population as a whole. Only when the population was subdivided by ethnicity was there convincing evidence of anticipation in the Jewish population.

CONCLUSION

Ascertainment bias may be responsible for the apparent anticipation observed in the CD population as a whole or in the nonJewish CD subgroup. However, the Jewish CD population displays strong evidence of anticipation even after correction for ascertainment bias.

Evidence for genetic anticipation in nodal osteoarthritis

OBJECTIVE

Evidence was sought for genetic anticipation (disease occurring at an earlier age in subsequent generations, with increasing severity) in nodal osteoarthritis (NOA).

METHODS

Age at symptom onset and disease severity was compared within 30 parent/offspring pairs with NOA. Correlation between the offspring age of disease onset and the parental age at conception was also assessed.

RESULTS

The age at onset of nodal symptoms was earlier in the offspring (43 years (95% confidence intervals (CI) 38 to 47) v 61 (CI 58 to 65); mean difference 18 years (CI 13 to 22): p < 0.001) as was larger joint symptom onset (48 years (CI 41 to 55) v 67 (CI 61 to 73); mean difference 20 years (CI 13 to 27): p < 0.01). A negative correlation existed between age of offspring symptom onset and parental age at conception. Fifteen (50%) offspring had similar or more extensive disease than their parents.

CONCLUSIONS

These results suggest genetic anticipation occurs in NOA and if confirmed a search for trinucleotide repeats is warranted.

Genetics of psoriasis: paternal inheritance and a locus on chromosome 6p

The pathogenesis of psoriasis is not fully understood, but population and twin studies suggest a large heritable component to the etiology. Several large population studies have also suggested a parental sex effect. Since 1994, three main genetic loci (on chromosomes 17q, 4q, and 6p) have been reported in genome scans. With a view to elucidating the genetic basis of psoriasis, we have carried out linkage analysis in a large number of families with well-characterized psoriasis. From a cohort of 1250 probands with psoriasis, 395 individuals (301 affected, 94 unaffected) in 103 families were recruited. Each subject was carefully examined by an experienced dermatologist and stringent diagnostic criteria applied. Genotypes were generated at 11 polymorphic loci on chromosomes 17q, 4q, and 6p and the results were analyzed parametrically and nonparametrically. In the population from which the probands were drawn, there was evidence of a parental sex effect, more probands having an affected father than an affected mother. Genetic anticipation was also apparent and most marked if the disease was inherited from the father. The loci on chromosomes 17 and 4 were not replicated but there was strong evidence for linkage to chromosome 6p (maximum two point LOD score 4.63 at D6S291). The evidence for linkage in sibling pair analysis was greatest when the allele was of paternal origin and was most significant in those families without psoriatic arthritis. These studies confirm the presence of a susceptibility gene on chromosome 6p. The available evidence suggests that a different genetic susceptibility may underlie psoriasis and psoriatic arthritis.

Mapping susceptibility loci in inflammatory bowel disease: why and how?

The cause of the inflammatory bowel diseases Crohn's disease and ulcerative colitis is unknown, but epidemiological evidence suggests that it is multifactorial with a strong genetic component. Several genetic loci probably contribute to disease susceptibility, accounting for the complex pattern of inheritance and heterogeneous clinical manifestations. The combination of candidate gene studies and, more recently, genome-wide searches has resulted in the identification of a number of putative susceptibility loci. With large-scale, fine-mapping studies under way, and accelerating progress in the physical mapping of the human genome, rapid progress is now being made towards the identification of the genes responsible for inflammatory bowel disease.

Inflammatory bowel diseases: health care and costs in Sweden in 1994

BACKGROUND

Inflammatory bowel disease (IBD) has highly variable course and severity. Since comprehensive data on its impact are scarce, we analyzed all IBD care and costs in Sweden (population, 8.8 million).

METHODS

A cross-sectional observational study, using national registers and surveys on ambulatory care, hospital admissions, medication, sickness leave, and early retirement for IBD in 1994, was carried out. We calculated direct health care costs and indirect 1-year costs caused by morbidity.

RESULTS

Ambulatory care was concentrated to specialists in internal medicine at hospitals. One-fourth of the patients accounted for 48% of 1994 hospital admissions. Medication was predominantly aminosalicylates and steroids. Sickness leave episodes were long--on average, 6 weeks. Although uncommon, early retirements lasted 14 years on average. With regard to the underlying prevalence, the use of health care and compensations by Crohn's disease patients was two to four times that of patients with ulcerative colitis. Morbidity took 68% of total costs. Among direct costs, admissions accounted for 58%. Neither complications nor surveillance added much.

CONCLUSION

Ulcerative colitis is twice as common as Crohn's disease. In health care use, these roles are reversed. Since morbidity causes two-thirds of the costs, comprehensive analyses, including indirect costs, are necessary when evaluating new diagnostics and therapies.

The role of Peyer's patches in the age-related incidence of Crohn's disease

Recently researchers have suggested that clinical subsets of Crohn's disease occur, which are variously described as inflammatory, fibrostenotic, and fistulizing. In addition, it has been observed that within families with multiple cases, often there is concordance of the site and type of disease. The lesions of Crohn's disease occur in segments that suggest that distribution of Peyer's patches. When the age-related incidence of Crohn's disease was plotted for all countries from which such data were available, the peaks of greatest case frequency occurred at ages 15 to 25 years and paralleled a similar peak representing the number of Peyer's patches as a function of age. This correlation suggests that Crohn's disease may develop as an inflammatory process specifically targeting these important lymphoid structures. Similar peaks of activity in the adolescent to early adult years occur for appendicitis and tonsillitis.