Étude des gènes candidats reliés à l'hypertension artérielle et l'obésité dans une population hypertendue du Saguenay-Lac-Saint-Jean

Thèse numérisée par la Direction des bibliothèques de l'Université de Montréal

Layered founders : a novel approach to investigate the ancestral transmission of complex traits

A novel approach based on graph theory is presented to reason about the genetic contribution of ancestors at different genealogical distances from today's individuals (different definitions of layers and distances are propos ed and discussed). It allows the maximum likelihood classification of specific founders who predominantly contribute to one class of individuals and the analysis of separability of specific founders with respect to two classes of individuals that have been selected based on LOD (logarithm of odds) score determined by a total genome scan and on ScaI marker genotype of a candidate gene of hypertension, ANP. Several experiments have been performed on a genealogy comprising more than 40,000 people and spanning 17 generations from the Saguenay-Lac-Saint-Jean population. We have computed: the founders obtained by using different definitions of layers and distances, the contribution of specific and unique founders, and the separability of specific founders. The results indicate that most defini tions of layers of founders show a similar trend over layers for size and content, that specific and unique genetic contributions are very high for recent generations and, as expected, decrease for older generations, and, also, that separability is higher for recent generations than for older ones. The presented approach allows a much finer grain analysis of genetic contribution of founders than previously-reported approaches

Estimating the Impacts of Payroll Taxes: Evidence from Canadian Employer-Employee Tax Data

In this paper, we use linked employer-employee administrative tax data from Canada to estimate the impact of payroll taxes on a variety of firms and workers outcomes. At the firm level, we use geographic and time variations in tax rates to identify the effect of payroll taxes on wage growth at the worker level. For one province, we exploit a clean overtime change in the payroll tax rate to estimate its impact on the firm's level of employment, average wage and productivity, with difference-in-differences models, taking into account firm-level unobserved heterogeneity. Additionally, taking advantage of the nature of linked data, we estimate wage equations with both fixed worker and firm fixed effects. We find no impact on employment, productivity and profits, but significant impacts on wages, implying that payroll taxes are passed almost entirely to workers in the form of lower wages