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Whole-exome or gene targeted resequencing in hundreds to thousands of individuals has shown that the majority of genetic variants are at low frequency in human populations. Rare variants are enriched for functional mutations and are expected to explain an important fraction of the genetic etiology of human disease, therefore having a potential medical interest. In this work, we analyze the whole-exome sequences of French-Canadian individuals, a founder population with a unique demographic history that includes an original population bottleneck less than 20 generations ago, followed by a demographic explosion, and the whole exomes of French individuals sampled from France. We show that in less than 20 generations of genetic isolation from the French population, the genetic pool of French-Canadians shows reduced levels of diversity, higher homozygosity, and an excess of rare variants with low variant sharing with Europeans. Furthermore, the French-Canadian population contains a larger proportion of putatively damaging functional variants, which could partially explain the increased incidence of genetic disease in the province. Our results highlight the impact of population demography on genetic fitness and the contribution of rare variants to the human genetic variation landscape, emphasizing the need for deep cataloguing of genetic variants by resequencing worldwide human populations in order to truly assess disease risk., Competing Interests: The authors have declared that no competing interests exist.

Unlabelled: Evans' Syndrome (ES) is defined as the combination of immune thrombocytopenia (ITP) and autoimmune haemolytic anemia (AIHA), in the absence of any known underlying etiology. Pathophysiology, epidemiology and outcome remain unclear., Population: Thirty-six children (20 male, 16 female), who were diagnosed in the SHIP french centres (Société d'hématologie et d'immunologie pédiatrique) between 1990 and 2002 with ES, were included in this retrospective study., Results: Median age at diagnosis was 4 years. In 21 children, ES occurred in the setting of consanguinity, family history of autoimmune/inflammatory disease, associated autoimmune disorder or immunoregulatory abnormalities (serum imunoglobulins, peripheral blood lymphocytes subsets, low level of the C3-C4 complement components, nuclear antibodies). Several successive treatments were used in this serie (median: 3, range: 0-10) including corticosteroid therapy (35/36), intravenous immunoglobulins (32/36), immunosuppressive agents (14/36), splenectomy (9/36) and anti CD 20 monoclonal antibodies (6/36). Patients with a low level of serum immunoglobulins were more often non-responders to corticosteroidtherapy/intravenous immunoglobulins and required more frequently further therapy (P=0.03). Three patients died (intracranial bleeding, N=2, Guillain-Barre syndrome; N=1)., Conclusion: ES was a severe, life-threatening disease, requiring aggressive immunosuppressive therapy in as many as half the patients. Our forthcoming study aims to (i) describe homogeneously-studied and prospectively-analysed cohort of childhood ES, (ii) separate ES from specific immune deficiency (especially fas gene mutations), generalised autoimmune/inflammatory disorders and genetic diseases, (iii) identify well-defined ES subsets, (iv) establish prognostic factors and optimal treatment within these subsets.

Objective: Disseminated bacillus Calmette-Guérin (BCG) infection after inoculation of live vaccine is considered to result from impaired immunity of the child. However, in half of the cases, regarded as idiopathic, no well-defined immunodeficiency condition can account for the infection. The objective of the present study is to report the prevalence, clinical features, associated infections, and outcomes of children with idiopathic disseminated BCG infection., Design: National retrospective survey during the period from 1974 through 1994 in France., Setting: All neonatology and pediatrics units in primary care and referral centers throughout France., Patients: Data were collected from 595 (82%) of 721 units, 377 (93%) of 407 centers, and 320 (93%) of 345 cities. Selection criteria included BCG infection, dissemination to at least two areas beyond the inoculation site, and no well-defined immunodeficiency condition. Sixteen children (8 girls and 8 boys), born to families unrelated to each other but often consanguinous (5 of 16) or abroad (5 of 16)., Results: The minimal prevalence rate was estimated at 0.59 cases per 1 million vaccinated children born in France. Clinical features included fever and cachexia, disseminated BCG infection to lymph nodes (15 of 16), skin (13 of 16), soft tissues (11 of 16), lungs (11 of 16), spleen (11 of 16), liver (11 of 16), and bones (9 of 16). Eight children had associated or subsequent severe opportunistic infection (50%), with either nontyphi Salmonella enterica serotypes (7 of 16) or Mycobacterium abscessus (1 of 16). The outcome was poor: 8 children (50%) died; the cause of death was BCG infection for most children (7 of 8); 8 survived until the last follow-up (50%)., Conclusions: Idiopathic disseminated BCG infection is a rare but severe complication of BCG vaccination. The infection probably results from an as yet unknown genetically determined immunodeficiency condition that affects the killing of intracellular bacteria such as BCG and Salmonella.