Genetic factors underlying gluten-sensitive enteropathy

The contribution of genes to osteoarthritis

Osteoarthritis (OA) is the most prevalent form of arthritis in the elderly. A large body of evidence, including familial aggregation and classic twin studies, indicates that primary OA has a strong hereditary component that is likely polygenic in nature. Traits related to OA, such as longitudinal changes in cartilage volume and progression of radiographic features, are also under genetic control. In recent years several linkage analyses and candidate gene studies have been performed and unveiled some of the specific genes involved in disease risk, such as FRZB and GDF5. This article discusses the impact that future genome-wide association scans can have on our understanding of the pathogenesis of OA and on identifying individuals at high risk for developing severe OA.

The contribution of genes to osteoarthritis

Osteoarthritis (OA) is the most prevalent form of arthritis in the elderly. A large body of evidence, including familial aggregation and classic twin studies, indicates that primary OA has a strong hereditary component that is likely polygenic in nature. Furthermore, traits related to OA, such as longitudinal changes in cartilage volume and progression of radiographic features, are also under genetic control. In recent years, several linkage analysis and candidate gene studies have been performed and have unveiled some of the specific genes involved in disease risk, such as FRZB and GDF5. The authors discuss the impact that future genome-wide association scans can have on our understanding of the pathogenesis of OA and on identifying individuals at high risk for developing severe OA.

The MYO9B gene is a strong risk factor for developing refractory celiac disease

BACKGROUND & AIMS

Celiac disease (CD) is associated with HLA-DQ2 and HLA-DQ8 and has been linked to genetic variants in the MYO9B gene on chromosome 19. HLA-DQ2 homozygosity is associated with complications of CD such as refractory celiac disease type II (RCD II) and enteropathy-associated T-cell lymphoma (EATL). We investigated whether MYO9B also predisposes to RCD II and EATL.

METHODS

Genotyping of MYO9B and molecular HLA-DQ2 typing were performed on 62 RCD II and EATL patients, 421 uncomplicated CD patients, and 1624 controls.

RESULTS

One single nucleotide polymorphism in MYO9B showed a significantly different allele distribution in RCD II and EATL patients compared with controls (P = .00002). The rs7259292 T allele was significantly more frequent in RCD II and EATL patients compared with CD patients (P = .0003; odds ratio [OR], 3.61; 95% confidence interval [CI], 1.78-7.31). The frequency of the haplotype carrying the T allele of this single nucleotide polymorphism was significantly increased in RCD II and EATL patients (11%), compared with controls (2%) and CD patients (3%) (OR, 6.76; 95% CI, 3.40-13.46; P = 2.27E-09 and OR, 4.22; 95% CI, 1.95-9.11; P = .0001, respectively). Both MYO9B rs7259292 and HLA-DQ2 homozygosity increase the risk for RCD II and EATL to a similar extent when compared with uncomplicated CD patients (OR, 4.3; 95% CI, 1.9-9.8 and OR, 5.4; 95% CI, 3.0-9.6, respectively), but there was no evidence for any interaction between these 2 risk factors.

CONCLUSIONS

We show that both MYO9B and HLA-DQ2 homozygosity might be involved in the prognosis of CD and the chance of developing RCD II and EATL.

[Genetics and immunopathogenics aspects of the celiac disease: a recent vision]

BACKGROUND

Celiac disease, or gluten-sensitive enteropathy, is a strongly inherited condition. Although the genetic association of CD with the DQ2 and DQ8 HLA haplotypes has been known for long, others HLA and non-HLA genes are also important in the development of the disease. Celiac disease results of the combined effect of different normally functioning genes' products. The tissue damage in celiac disease is immunologically mediated and several effector mechanisms are responsible for the disease expression. The interplay between genetic, immunological and environmental factors explains the large spectrum of clinical, histological and serological alterations observed in the different stages of the disease development, pointing out to the polygenic nature of celiac disease.

CONCLUSION

The recent advances in the understanding of the immunopathogenesis, genetics and diagnoses of celiac disease have allowed the revision of strict concepts and previous criteria and their adequation to the new evidences, aiming a better diagnostic and orientation to celiac patients and relatives.

The interferon gamma gene in celiac disease: augmented expression correlates with tissue damage but no evidence for genetic susceptibility

Celiac disease (CD) is a complex genetic disorder characterized by gluten intolerance. The Th1 immune response, with a key position for interferon gamma (IFN-gamma), is an important determinant of intestinal remodeling in CD. We aimed at further ascertaining the role of IFN-gamma, either as a genetic factor in the etiology, or as a facilitator of disease initiation/progression. Duodenal biopsies were sampled across distinct histopathological stages of the disease, including refractory CD (RCD), and used to determine IFN-gamma gene (IFNG) expression by real-time RT-PCR. INFG expression correlated with the extent of tissue restructuring, reaching a 240-fold higher expression in total villous atrophy compared to healthy tissue. CD and RCD patients with similar lesions had comparable expression levels. Interestingly, patients in complete remission still had 7.6-fold residual over-expression. An INFG marker was tested in three cohorts of Dutch patients for both genetic linkage and association. Linkage analysis yielded no significant scores for IFNG or its flanking markers. In addition, IFNG allele frequencies were not differently distributed between cases and controls. Likewise, all alleles were randomly transmitted to affected children in parents-case trios. There is no evidence for IFNG as a predisposing gene in CD, despite its enhanced expression in patients in complete remission.

Familial occurrence of inflammatory bowel disease in celiac disease

BACKGROUND

The authors have previously reported a possible increased risk of the familial occurrence of Crohn's disease in patients with celiac disease.

AIM

The aim of the current study was to evaluate in a case-control study the familial occurrence of inflammatory bowel disease (IBD) in first-degree relatives of patients with celiac disease.

METHODS

One hundred eleven consecutive patients with biopsy-proven celiac disease were interviewed to ascertain whether IBD was present in first-degree relatives. The number of relatives, their ages, and possible IBD status were collected in a questionnaire. When a diagnosis of familial IBD was reported, the diagnosis was checked in the hospital records. Two hundred twenty-two controls matched for age and sex (111 from the general population and 111 from orthopedic wards) were also interviewed regarding the possible occurrence of IBD in first-degree relatives. The chi2 test was used to evaluate the difference in proportion of familial occurrence of IBD among individuals with celiac disease and controls.

RESULTS

Among 600 first-degree relatives of patients with celiac disease, 10 cases of IBD were identified among first-degree relatives (7 cases of ulcerative colitis and 3 cases of Crohn's disease), whereas only 1 case of IBD was identified among the 1,196 first-degree relatives of control patients (p < 0.01). When ulcerative colitis and Crohn's disease were analyzed separately, only the prevalence of ulcerative colitis was statistically significant (p </= 0.02).

CONCLUSIONS

This case-control study shows that there is a significantly increased prevalence of familial ulcerative colitis in patients with celiac disease. There was no significant increase in the prevalence of Crohn's disease in patients with celiac disease. The possible role of this association is discussed.