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  1. Article ; Online: Controlling for human population stratification in rare variant association studies

    Matthieu Bouaziz / Jimmy Mullaert / Benedetta Bigio / Yoann Seeleuthner / Jean-Laurent Casanova / Alexandre Alcais / Laurent Abel / Aurélie Cobat

    Scientific Reports, Vol 11, Iss 1, Pp 1-

    2021  Volume 14

    Abstract: Abstract Population stratification is a confounder of genetic association studies. In analyses of rare variants, corrections based on principal components (PCs) and linear mixed models (LMMs) yield conflicting conclusions. Studies evaluating these ... ...

    Abstract Abstract Population stratification is a confounder of genetic association studies. In analyses of rare variants, corrections based on principal components (PCs) and linear mixed models (LMMs) yield conflicting conclusions. Studies evaluating these approaches generally focused on limited types of structure and large sample sizes. We investigated the properties of several correction methods through a large simulation study using real exome data, and several within- and between-continent stratification scenarios. We considered different sample sizes, with situations including as few as 50 cases, to account for the analysis of rare disorders. Large samples showed that accounting for stratification was more difficult with a continental than with a worldwide structure. When considering a sample of 50 cases, an inflation of type-I-errors was observed with PCs for small numbers of controls (≤ 100), and with LMMs for large numbers of controls (≥ 1000). We also tested a novel local permutation method (LocPerm), which maintained a correct type-I-error in all situations. Powers were equivalent for all approaches pointing out that the key issue is to properly control type-I-errors. Finally, we found that power of analyses including small numbers of cases can be increased, by adding a large panel of external controls, provided an appropriate stratification correction was used.
    Keywords Medicine ; R ; Science ; Q
    Subject code 310
    Language English
    Publishing date 2021-09-01T00:00:00Z
    Publisher Nature Portfolio
    Document type Article ; Online
    Database BASE - Bielefeld Academic Search Engine (life sciences selection)

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  2. Article ; Online: IRF4 haploinsufficiency in a family with Whipple’s disease

    Antoine Guérin / Gaspard Kerner / Nico Marr / Janet G Markle / Florence Fenollar / Natalie Wong / Sabri Boughorbel / Danielle T Avery / Cindy S Ma / Salim Bougarn / Matthieu Bouaziz / Vivien Béziat / Erika Della Mina / Carmen Oleaga-Quintas / Tomi Lazarov / Lisa Worley / Tina Nguyen / Etienne Patin / Caroline Deswarte /
    Rubén Martinez-Barricarte / Soraya Boucherit / Xavier Ayral / Sophie Edouard / Stéphanie Boisson-Dupuis / Vimel Rattina / Benedetta Bigio / Guillaume Vogt / Frédéric Geissmann / Lluis Quintana-Murci / Damien Chaussabel / Stuart G Tangye / Didier Raoult / Laurent Abel / Jacinta Bustamante / Jean-Laurent Casanova

    eLife, Vol

    2018  Volume 7

    Abstract: Most humans are exposed to Tropheryma whipplei (Tw). Whipple’s disease (WD) strikes only a small minority of individuals infected with Tw (<0.01%), whereas asymptomatic chronic carriage is more common (<25%). We studied a multiplex kindred, containing ... ...

    Abstract Most humans are exposed to Tropheryma whipplei (Tw). Whipple’s disease (WD) strikes only a small minority of individuals infected with Tw (<0.01%), whereas asymptomatic chronic carriage is more common (<25%). We studied a multiplex kindred, containing four WD patients and five healthy Tw chronic carriers. We hypothesized that WD displays autosomal dominant (AD) inheritance, with age-dependent incomplete penetrance. We identified a single very rare non-synonymous mutation in the four patients: the private R98W variant of IRF4, a transcription factor involved in immunity. The five Tw carriers were younger, and also heterozygous for R98W. We found that R98W was loss-of-function, modified the transcriptome of heterozygous leukocytes following Tw stimulation, and was not dominant-negative. We also found that only six of the other 153 known non-synonymous IRF4 variants were loss-of-function. Finally, we found that IRF4 had evolved under purifying selection. AD IRF4 deficiency can underlie WD by haploinsufficiency, with age-dependent incomplete penetrance.
    Keywords Whipple's disease ; primary immunodeficiency ; IRF4 ; haploinsufficiency ; Medicine ; R ; Science ; Q ; Biology (General) ; QH301-705.5
    Subject code 610
    Language English
    Publishing date 2018-03-01T00:00:00Z
    Publisher eLife Sciences Publications Ltd
    Document type Article ; Online
    Database BASE - Bielefeld Academic Search Engine (life sciences selection)

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