The cancer pattern among Inuit in the Circumpolar area is remarkably different from those of other populations in the world. The current paper summarizes the most important risk factors in Canadian Inuit residing in the Northwest Territories, northern Quebec (Nunavik) and Labrador, particularly during the time period 1969-1988 covered by the study. Factors considered include: the geographic area and physical environment; population and human environment, including fertility and life expectancy; lifestyle and diet, including tobacco and alcohol use; other lifestyle factors, and health conditions; and health services and cultural accessibility. Development of the cancer registry and population databases supporting the analysis of cancer rates is described. The information in the present paper is needed to interpret cancer incidence patterns and differences among the Circumpolar Inuit of Canada, Alaska and Greenland.
To fully ascertain the familial aggregation of restless legs syndrome (RLS) and to characterize the clinical features of familial RLS (fRLS) cases.
A case series survey with a high response rate.
Academic research center.
Consecutive RLS probands (n = 249) were followed up in a specialized sleep center for 15 years. A total of 671 cases of fRLS met the current standard diagnostic criteria, including 192 probands characterized using multidimensional clinical assessments and 479 affected family members assessed by their responses to a structured questionnaire telephone diagnostic interview.
Sibling and offspring relative risk ratio and clinical and genetic features of patients with fRLS and families.
Our data showed that RLS aggregates in families with a familial rate of 77%, a sibling relative risk of 3.6 (95% confidence interval, 2.8-4.4), and an offspring relative risk of 1.8 (1.0-2.7). Familial RLS is a chronic disorder with a mean (SD) disease duration of 24 (16) years and a wide range of age of onset (mean [SD], 28  years), with most family members having early-onset disease but mild to moderate RLS symptoms. Our clinical data also indicated that fRLS is more prominent among women who also had increased incidence of anemia/iron deficiency, arthritis, and number of pregnancies. Pregnancy-related RLS seems to be a characteristic feature of fRLS, and afflicted women tend to have a much younger age of onset.
Restless legs syndrome significantly aggregated in families with variable phenotypic expressivity, and the siblings of severely affected individuals have an increased risk of developing the disease.
Some rare inherited disorders are found with a high frequency in the population of the Saguenay region (Québec province, Canada, population 300,000). Inbreeding coefficients are too low to be an explanation for these high frequencies. In the first decades of settlement (1842-1870), most of the immigrants came from a small region called Charlevoix (east of Québec city). As most of the genetic disorders found in the Saguenay region are also found in the Charlevoix region, it is strongly suspected that the genes were introduced by these first settlers from Charlevoix. Using the BALSAC database (which contains linked information on the entire Saguenay population) to calculate the number of contemporary descendants and the genetic contribution of each founder to these descendants, we show that: (1) Founders who entered the population before 1870 contribute to 45% of the contemporary gene pool, despite the fact that they represent only 15% of all the 20,012 immigrants with descendants in the contemporary population (individuals born between 1950 and 1971). (2) Their genetic contribution is not homogenous in the contemporary population: 5% of the population have 100% of their gene pool coming from these first founders, while 10% have a zero to 5% contribution from these earliest founders. (3) Fifty percent of the genes introduced in the population were lost. (4) If only 68 immigrants among the first founders (2.0%) were carriers of the same gene, it could reach a frequency of 5% in the contemporary population, which is the frequency of most of the inherited disorders found in the population.
Historical events have shaped the various regional gene pools of the French-Canadian (FC) population, leading to increased prevalence of some rare diseases. The first studies of these founder effects were performed in large part by astute clinicians such as André Barbeau. In collaboration with others, he contributed greatly to the delineation of phenotypic subtypes of these conditions. As such, the following neurogenetic disorders were first identified in patients of FC origin: AOA2, ARSACS, HSAN2, RAB, and HMSN/ACC. We have summarized our current knowledge of the main hereditary ataxias, spastic parapareses and neuropathies that are particular to the FC population. The initial genetic characterization of the more common and homogeneous of these diseases has been largely completed. We predict that the regional populations of Canada will allow the identification of new rare forms of hereditary ataxias, spastic parapareses and neuropathies, and contribute to the unravelling of the genetic basis of these entities.
The natural history of chronic hepatitis B in children is influenced by mode of transmission and varies with regional endemicity. Seroconversion rates were studied in 174 hepatitis B e antigen (HBeAg)-positive children who were of different ethnic origins and living in Canada. Overall, 40.2% became anti-HBeAg positive, and 8.6% were hepatitis B surface-antigen positive during a mean follow-up of 4.5 years. Spontaneous seroconversion rates were lower in Asian-born, mainly vertically infected, children, versus those born either in Canada or where horizontal transmission predominates (24% vs. 44%, P=.015). Kaplan-Meier analysis showed that the cumulative persistence of HBeAg after 13 years was 25% in Asian-born children, versus 6% in all others (P
Cree births in Quebec are characterized by the highest reported prevalence of macrosomia (~35%) in the world. It is unclear whether Cree births are at greater elevated risk of perinatal and infant mortality than other First Nations relative to non-Aboriginal births in Quebec, and if macrosomia may be related.
This was a population-based retrospective birth cohort study using the linked birth-infant death database for singleton births to mothers from Cree (n = 5,340), other First Nations (n = 10,810) and non-Aboriginal (n = 229,960) communities in Quebec, 1996-2010. Community type was ascertained by residential postal code and municipality name. The primary outcomes were perinatal and infant mortality.
Macrosomia (birth weight for gestational age >90th percentile) was substantially more frequent in Cree (38.0%) and other First Nations (21.9%) vs non-Aboriginal (9.4%) communities. Comparing Cree and other First Nations vs non-Aboriginal communities, perinatal mortality rates were 1.52 (95% confidence intervals 1.17, 1.98) and 1.34 (1.10, 1.64) times higher, and infant mortality rates 2.27 (1.71, 3.02) and 1.49 (1.16, 1.91) times higher, respectively. The risk elevations in perinatal and infant death in Cree communities attenuated after adjusting for maternal characteristics (age, education, marital status, parity), but became greater after further adjustment for birth weight (small, appropriate, or large for gestational age).
Cree communities had greater risk elevations in perinatal and infant mortality than other First Nations relative to non-Aboriginal communities in Quebec. High prevalence of macrosomia did not explain the elevated risk of perinatal and infant mortality in Cree communities.
Cites: Lancet. 2006 Jun 17;367(9527):2019-2816782493
Cites: Int J Epidemiol. 2004 Dec;33(6):1252-915319396
Using data from a cross-sectional survey on 570 fifteen year old students living in non-fluoridated public school sectors on the Island of Montreal in 1987, the effect of terminating the restorative aspect of public dental health care insurance for twelve to fifteen year old students is examined. This study also highlights the level and quality of dental caries treatment on the twelve to fifteen year old group. The main point to be made is that there was an improvement in the DMFT index values of fourteen and fifteen year old students in metropolitan areas. In reality, fourteen year old children had a DMFT index of 6.45 in 1983-1984, while the fifteen year old children in the 06A region (non-fluoridated area) had a DMFT of 6.07 in 1987. Since the metropolitan fluoridated area had been eliminated from the results in 1987, it is quite obvious that the 6.07 result obtained overestimates the actual prevalence of dental caries in the metropolitan area in 1987. On the other hand, the progress which had been recorded between 1977 and 1984 by francophones in relation to anglophones was partially lost in 1987. Furthermore, this study has demonstrated that the prevalence and level of dental caries treatment are highly associated with the language spoken at home and also with the family's socio-economic status.
External-beam radiation therapy (EBRT) may predispose to secondary malignancies that include bladder cancer (BCa), rectal cancer (RCa), and lung cancer (LCa). We tested this hypothesis in a large French Canadian population-based cohort of prostate cancer patients.
Overall, 8,455 radical prostatectomy (RP) and 9,390 EBRT patients treated between 1983 and 2003 were assessed with Kaplan-Meier and Cox regression analyses. Three endpoints were examined: (1) diagnosis of secondary BCa, (2) LCa, or (3) RCa. Covariates included age, Charlson comorbidity index, and year of treatment.
In multivariable analyses that relied on incident cases diagnosed 60 months or later after RP or EBRT, the rates of BCa (hazard ratio [HR], 1.4; p = 0.02), LCa (HR, 2.0; p = 0.004), and RCa (HR 2.1; p