Power comparison of different methods to detect genetic effects and gene-environment interactions

Identifying gene-environment (G × E) interactions has become a crucial issue in the past decades. Different methods have been proposed to test for G × E interactions in the framework of linkage or association testing. However, their respective performances have rarely been compared. Using Genetic Analysis Workshop 15 simulated data, we compared the power of four methods: one based on affected sib pairs that tests for linkage and interaction (the mean interaction test) and three methods that test for association and/or interaction: a case-control test, a case-only test, and a log-linear approach based on case-parent trios. Results show that for the particular model of interaction between tobacco use and Locus B simulated here, the mean interaction test has poor power to detect either the genetic effect or the interaction. The association studies, i.e., the log-linear-modeling approach and the case-control method, are more powerful to detect the genetic effect (power of 78% and 95%, respectively) and taking into account interaction moderately increases the power (increase of 9% and 3%, respectively). The case-only design exhibits a 95% power to detect G × E interaction but the type I error rate is increased

Essai d'interprétation génétique et environnementale des ressemblances familiales pour le poids et la taille à la naissance. L'exemple d'Ammassalik (Groenland oriental)

Summary. — Height and weight at birth were recorded from 1956 to 1990 in Ammassalik district (Groenland). Data were first adjusted for sex, birth rank order, mother's residence, and different period of birth. Pedigrees were drawn and correlations between children and various relatives (parents, sib, mother's and father's half-sib, uncle and aunt...) were estimated. Correlations are found to be significant only when mother's line is involved. Genetic and non genetic interpretations are discussed.Résumé. — La reconstitution des généalogies des enfants nés dans le district ď Ammassalik (Groenland) entre 1956 et 1990 a permis d'étudier les corrélations familiales entre les poids et tailles de naissance des enfants et de plusieurs de leurs apparentés (parents, germains, demi-germains de même père et de même mère, oncles et tantes etc.). Ces corrélations ont été calculées après standardisation pour tenir compte des effets du sexe, du rang de naissance, du lieu d'habitation de la mère et des fluctuations en fonction des générations. Ces corrélations se trouvent être significatives dans la lignée maternelle mais non dans la lignée paternelle. Plusieurs hypothèses, génétiques et non génétiques, sont discutées.Guilloud-Bataille Michel, Darlu Pierre, Rovillé-Sausse Françoise, Gessain Robert, Robert-Lamblin Joëlle. Essai d'interprétation génétique et environnementale des ressemblances familiales pour le poids et la taille à la naissance. L'exemple d'Ammassalik (Groenland oriental). In: Bulletins et Mémoires de la Société d'anthropologie de Paris, Nouvelle Série. Tome 5 fascicule 1-2, 1993. pp. 41-52

Taille et poids de naissance des enfants d'Ammassalik (Groenland Oriental), 1956-1990.

Summary. — 2342 children born in Ammassalik (Eastern Greenland) were measured at birth since 1956. Weight and height were increasing from 1956 to 1990, while demographic transition and changes in lifestyle and socio-economical conditions occured. There is a slight difference for height and weight at birth between Tasiilaq (village with hospital) and the other smaller villages. These measures are not found different in children born from native parents and from mix-marriages.Résumé. — 2342 enfants nés à Ammassalik (Groenland Oriental) à partir de 1956 ont été mesurés à la naissance. Les poids et tailles de naissance ont augmenté entre 1956 et 1990 en même temps que se produisaient la transition démographique et les changements socio-économiques des conditions de vie. Les enfants nés à Tasiilaq (petite ville avec hôpital) ont une taille et un poids de naissance supérieurs à ceux nés dans les autres plus petits villages. Il n'y a pas de différence entre les enfants de parents autochtones et ceux issus de mariages mixtes.Rovillé-Sausse Françoise, Gessain Robert, Guilloud-Bataille Michel, Robert-Lamblin Joëlle, Darlu Pierre. Taille et poids de naissance des enfants d'Ammassalik (Groenland Oriental), 1956-1990.. In: Bulletins et Mémoires de la Société d'anthropologie de Paris, Nouvelle Série. Tome 5 fascicule 1-2, 1993. pp. 29-39

Evidence for a locus in 1p31 region specifically linked to the co-morbidity of asthma and allergic rhinitis in the EGEA study.

International audienceOBJECTIVE: A recent genome scan conducted in French EGEA families led to detect linkage of 1p31 to either asthma or allergic rhinitis (AR) and more significantly to asthma associated with AR. The goal of the present study was to assess formally whether 1p31 is a linkage region shared by two different diseases, asthma and AR, or whether it is specific to the co-morbidity asthma plus AR. METHODS: We used two different statistical approaches: the Triangle Test Statistic (TTS) and the Predivided Sample Test (PST), to search for heterogeneity of linkage to 1p31 according to the affection status being defined by either the presence of the two diseases (asthma plus AR) or the presence of only one disease ('asthma only' or 'AR only' or 'asthma only or AR only'). RESULTS: While no heterogeneity between the 'two diseases' phenotype and the 'one disease' phenotype was detected by the TTS, there was significant evidence for heterogeneity (p = 0.00007/0.002 after correction for multiple testing) using the PST. There was no indication of linkage in sib-pairs with 'one disease' only, while there was significant evidence for linkage in sib-pairs displaying asthma plus AR (p = 0.0002/0.0016 after correction). CONCLUSION: The present analysis shows that the co-morbidity, asthma plus AR, represents a phenotypic entity, distinct from asthma only or AR only, controlled by a genetic factor located on 1p31