The mystery of primary biliary cirrhosis in British Columbia's First Nations people

Ethnicity, disease severity, and survival in Canadian patients with primary biliary cholangitis

BACKGROUND AND AIMS

We investigated associations between ethnicity, survival, and disease severity in a diverse Canadian cohort of patients with primary biliary cholangitis (PBC).

APPROACH AND RESULTS

Patients with PBC were included from the Canadian Network for Autoimmune Liver Disease. Ethnicity was defined using a modified list adopted from Statistics Canada, and ethnicities with small samples were grouped. Clinical events were defined as liver decompensation, HCC, liver transplantation, or death. Clinical event-free and liver transplantation-free survival were analyzed using Cox regression. Trajectories of serum liver function tests were assessed over time using mixed-effects regression. Health-related quality of life was assessed using the Short Form 36, the PBC-40 questionnaire, and the 5-D Itch scale and analyzed using mixed-effects regression. The cohort included 1538 patients with PBC from six sites and was comprised of 82% White, 4.7% Indigenous, 5.5% East Asian, 2.6% South Asian, and 5.1% miscellaneous ethnicities. Indigenous patients were the only ethnic group with impaired liver transplant-free and event-free survival compared to White patients (HR, 3.66; 95% CI, 2.23-6.01; HR, 3.09; 95% CI, 1.94-4.92). Indigenous patients were more likely to have a clinical event before diagnosis (10%) than all other ethnic groups despite similar age at diagnosis. Indigenous patients presented with higher alkaline phosphatase, total bilirubin, and GLOBE scores than White patients; and these relative elevations persisted during follow-up.

CONCLUSIONS

Indigenous Canadians with PBC present with advanced disease and have worse long-term outcomes compared to White patients.

Comparative United States autoimmune disease rates for 2010-2016 by sex, geographic region, and race

PURPOSE

AIDs may disproportionately impact specific racial groups, but autoimmune (AID) prevalence information by minority racial group is sparse for many AIDs. The objective of this analysis was to supplement previously published AID prevalence rates by providing information on race rate ratios (minority race populations compared to Caucasian populations) in the United States. Preliminary to estimating race rate ratios, contemporary US-specific, health care utilization-based AID prevalence rates and female-to-male ratios were estimated and compared to previously published AID prevalence rates.

METHODS

We used a large national electronic medical record database of 52 million individuals to estimate age-adjusted direct standardized rates for 22 AIDs for 2010 through 2016 by gender, race, and US census division. These were compared to previously published estimates.

RESULTS

Female-to-male ratios were comparable with published studies. Almost all observed Multiracial AID rates were significantly higher than Caucasian rates, as well as 9 of 22 AID rates observed among Native Americans and 8 of 22 AID rates estimated among African-American patients. Regional variation was noted: highest African-American systemic lupus erythematosus rates were observed in the West North Central and South Atlantic divisions, highest African-American multiple sclerosis rates in the South Atlantic and Pacific divisions, and highest Native American rheumatoid arthritis rates in the West North Central, Mountain, and Pacific divisions.

CONCLUSIONS

Substantial AID heterogeneity exists by race and by geographic area. An important research area is further exploring factors related to heterogeneity such as potential interactions between genetic susceptibility and environmental factors.

Primary Biliary Cholangitis in British Columbia First Nations: Clinical features and discovery of novel genetic susceptibility loci

BACKGROUND & AIMS

Primary Biliary Cholangitis (PBC) is a chronic autoimmune liver disease characterized by destruction of intrahepatic bile ducts, portal inflammation and cirrhosis. Although rare in most populations, it is prevalent and often familial in British Columbia First Nations. We hypothesized that major genetic factors increased the risk in First Nations.

METHODS

In all, 44 individuals with Primary Biliary Cholangitis and 61 unaffected relatives from 32 First Nations families participated. Family history and co-morbidities were documented. Medical records were reviewed and available biopsies were re-reviewed by our team pathologist. Genotyping was performed on DNA from 36 affected persons and 27 unaffected relatives using the Affymetrix Human Mapping 500K Array Set. MERLIN software was used to carry out multipoint parametric and nonparametric linkage analysis. Candidate genes were identified and entered into InnateDB and KEGG software to identify potential pathways affecting pathogenesis.

RESULTS

In all, 34% of families were multiplex. Fifty per cent of cases and 33% of unaffected relatives reported other autoimmune disease. Three genomic regions (9q21, 17p13 and 19p13) produced LOD scores of 2.3 or greater suggestive of linkage, but no single linkage peak reached statistical significance. Candidate genes identified in the three regions suggested involvement of IL17, NFκB, IL6, JAK-STAT, IFNγ and TGFβ immune signalling pathways. Specifically, four genes-ACT1, PIN1, DNMT1 and NTN1-emerged as having roles in these pathways that may influence Primary Biliary Cholangitis pathogenesis.

CONCLUSIONS

Our whole genome linkage study results reflect the multifactorial nature of Primary Biliary Cholangitis, support previous studies suggesting signalling pathway involvement and identify new candidate genes for consideration.

Genetic research and aboriginal and Torres Strait Islander Australians

While human genetic research promises to deliver a range of health benefits to the population, genetic research that takes place in Indigenous communities has proven controversial. Indigenous peoples have raised concerns, including a lack of benefit to their communities, a diversion of attention and resources from non-genetic causes of health disparities and racism in health care, a reinforcement of "victim-blaming" approaches to health inequalities, and possible misuse of blood and tissue samples. Drawing on the international literature, this article reviews the ethical issues relevant to genetic research in Indigenous populations and considers how some of these have been negotiated in a genomic research project currently under way in a remote Aboriginal community. We consider how the different levels of Indigenous research governance operating in Australia impacted on the research project and discuss whether specific guidelines for the conduct of genetic research in Aboriginal and Torres Strait Islander communities are warranted.

Celiac disease in native Indians from Brazil: A clinical and epidemiological survey

Background:

Celiac disease has been described in populations from around the world, with recent data emphasizing the occurrence of the disease in ethnic minorities. There are only a few studies evaluating celiac disease in native Indians.

Aims:

This study aimed to screen the anti-endomysial antibody (IgA-EmA) in Kaingang and Guarani Indians from southern Brazil, in order to establish a clinical serological evaluation of celiac disease in these individuals.

Material and Methods:

Serum samples from 321 individuals (125 male and 196 female; 4-86 years old) from Mangueirinha Indigenous Reserve, State of Parana, Brazil, and 180 non-Indigenous healthy individuals (62 male and 118 female; 2-81 years old) were analysed to the presence of anti-endomysial antibody class IgA by indirect immunofluorescence assay. Amongst the Indians, 158 were Kaingang, 98 Guarani and 65 of mixed race. Indians presenting complaints of diarrhea (N=12) were also evaluated to the IgG class of anti-endomisyal antibody.

Results:

None of the individuals showed positive results either to IgA or IgG anti-endomysial antibodies.

Conclusions:

Although the results indicate an absence of celiac disease in Kaingang and Guarani Indians, the authors call attention to the importance of following up indigenous children or adults presenting gastrointestinal complaints or other symptoms related to the disease. Consideration should be given to the genetic background of these individuals, allied to the inter ethnic marriages and the changing habits or occupational activities, that have gradually introduced diseases previously not described in indigenous populations.

Primary biliary cirrhosis: a 2010 update

Primary biliary cirrhosis (PBC) is a chronic inflammatory autoimmune disease that mainly targets the cholangiocytes of the interlobular bile ducts in the liver. The condition primarily affects middle-aged women. Without treatment, PBC generally progresses to cirrhosis and eventually liver failure over a period of 10-20 years. PBC is a rare disease with prevalence of less than 1/2000. PBC is thought to result from a combination of multiple genetic factors and superimposed environmental triggers. The contribution of the genetic predisposition is evidenced by the familial clustering. Several risk factors, including exposure to infectious agents and chemical xenobiotics, have been suggested. Ursodeoxycholic acid (UDCA) is currently the only FDA-approved medical treatment for PBC. When administered at doses of 13-15 mg/kg/day, a majority of patients with PBC have a normal life expectancy without additional therapeutic measures. One out of three patients does not adequately respond to UDCA therapy and may need additional medical therapy and/or liver transplantation. This review summarises current knowledge on the epidemiology, ethiopathogenesis, clinical, and therapeutic aspects of PBC.

Primary liver cancer incidence among American Indians and Alaska Natives, US, 1999-2004

BACKGROUND

American Indians and Alaska Natives (AI/AN) experience higher morbidity and mortality from primary liver cancer than other United States (US) populations, but racial misclassification in medical records results in underestimates of disease burden.

METHODS

To reduce misclassification, National Program of Cancer Registries and Surveillance, Epidemiology, and End Results data were linked with Indian Health Service (IHS) enrollment records to compare primary liver cancer incidence and stage at diagnosis between AI/AN and non-Hispanic whites (NHW) living within the regionalized IHS Contract Health Service Delivery Area counties. Incidence rates are expressed per 100,000 persons and age-adjusted by 19 age groups to the 2000 US standard population.

RESULTS

Overall, AI/AN have a higher proportion of hepatocellular carcinoma compared with NHW, 77.8% versus 66.7%. Liver cancer incidence rates among AI/AN males and females were higher than those among NHW males and females for all regions except for the East. Among males, rates ranged from 7.3 (95% confidence interval [CI], 3.8-12.6) in the East to 17.2 (95% CI, 10.4-26.3) in Alaska. Among females, rates ranged from 3.8 (95% CI, 1.4-8.2) in the East to 6.9 (95% CI, 3.6-11.6) in Alaska. The AI/AN rates for all regions were consistently higher than the NHW rates at every age. An increasing trend among AI/AN was suggested but did not achieve statistical significance.

CONCLUSIONS

Reducing racial misclassification revealed higher disparities in primary liver cancer incidence between NHW and AI/AN populations than previously reported. Further description of the reasons for regional differences in this disparity is needed, as are programs to reduce risk factors and to diagnose primary liver cancer at earlier, more treatable stages.

Recent advances in the epidemiology of primary biliary cirrhosis

Since initial reports in the mid-1970s provided epidemiology data on primary biliary cirrhosis (PBC), many studies have characterized the variable frequency of this disease in diverse populations worldwide and sought to identify associated risk factors. Recent research confirms earlier work suggesting that the incidence and prevalence of PBC are on the rise, although geographic variation persists. Analysis of familial and geographic clustering supports the hypothesis that development and progression of the disease hinge on a complex interplay between genetic and environmental risk factors. International clinical data systems are needed to advance PBC epidemiologic research. Given this complexity, international clinical data systems are needed to advance PBC epidemiologic research.

Retrospective review of pediatric and adult autoimmune hepatitis in two quaternary care centres in British Columbia: increased prevalence seen in British Columbia's First Nations community

BACKGROUND

It has been previously reported that British Columbia's (BC's) First Nations (Aboriginal) community has an increased risk of autoimmune diseases, including rheumatological conditions (rheumatoid arthritis, systemic lupus) and primary biliary cirrhosis. The researchers hypothesized that this community may also be at increased risk for autoimmune hepatitis (AIH).

METHODS

Independent, retrospective reviews of the databases of two separate tertiary/quaternary British Columbia university-affiliated health care institutions, the Adult Liver Transplant Program of the BC Transplant Society and the Division of Pediatric Gastroenterology, BC Children's Hospital (Vancouver, BC), were performed. All patients referred with a diagnosis of probable or definite AIH who identified themselves as being of First Nations descent from 1988 to 2004 were reviewed. The liver transplant database records all adult patients in the province referred for transplant assessment. The pediatric database records all children referred to the BC Children's Hospital.

RESULTS

A total of 68 adult patients with a definite or probable diagnosis of AIH were referred to the liver transplant program. Twelve patients (17.6%) were Aboriginal, 11 of which were female. Similarly, a total of 30 children with probable or definite AIH were identified from the pediatric database. Six of these cases (20%) were identified in Aboriginal children.

CONCLUSIONS

The findings suggest an increased prevalence of AIH among BC's First Nations community. A disproportionate First Nations representation was found on independent review of two databases. Future studies are needed to determine the true prevalence of AIH in this community, and to uncover the genetic predisposition and the environmental triggers explaining this phenomenon.

DNA on loan: issues to consider when carrying out genetic research with aboriginal families and communities

In the current research milieu where genetic etiology is considered a critical component in the discovery of pathogenesis, aboriginal families and communities affected with genetic conditions may be considered as research participants. However, because of concerns about the impact of genetic information and historical harmful research practices, some aboriginal communities have considerable unease when faced with this prospect. Therefore, in the circumstance that genetics is considered an important part of research inquiry by aboriginal families and communities, there needs to be assurance that the research will be carried out according to mutual expectations. A research relationship that respects aboriginal individuals and communities within their culture and is in keeping with their values is essential. This respect extends to the use of biological samples, considering the DNA to be 'on loan' to the researcher for the purpose of the research for which consent was obtained. This paper will explore practical ways of maintaining a respectful research relationship when genetics research with aboriginal people is undertaken.

Autoimmune liver disease and the Canadian First Nations Aboriginal Communities of British Columbia’s Pacific Northwest

Primary biliary cirrhosis (PBC) is a well-known but uncommon chronic liver disease that is presumed to be of autoimmune etiology. Recently, investigations in British Columbia (BC), a province of Canada situated along the Pacific North-West of North America, have suggested that PBC is not a rare disease amongst BC’s Aboriginal (i.e. First Nations) communities. Geographically, BC is adjacent to South East Alaska, an American state that has also reported an increased prevalence of PBC amongst its Aboriginal communities. In this article, the medical evidence supporting a hypothesis of increased risk of PBC amongst BC’s First Nations communities is reviewed. Evidence suggesting that autoimmune hepatitis is also more likely amongst BC’s First Nations communities is also presented.