Segregation analysis of height-adjusted weight with generation- and age-dependent effects: the Nancy Family Study.

A segregation analysis using a regressive model with generation- and age-dependent effects was applied to familial data of height-adjusted weight to investigate the major gene hypothesis. The sample included 629 nuclear families with 2,534 members volunteering for a free health check-up in the Preventive Medicine Center of Vandoeuvre-lès-Nancy, France. The familial correlations were 0.094 +/- 0.040 between spouses, 0.198 +/- 0.023 between parent and offspring, and 0.327 +/- 0.034 between siblings. The variability of the trait was higher in parents than in offspring. The most parsimonious genetic model indicated a codominant major effect increasing with age in childhood, then stabilizing in adulthood. The same data were analyzed using the classical mixed model, assuming equality of variances between parents and offspring, no resemblance between spouses, similar parent-offspring and sib-sib correlations, and identical effects in parents and offspring. This analysis indicated a recessive solution. In both analyses, mendelian transmission was rejected. However, the mixture of two distributions in the recessive model, instead of three in the codominant one, was less constraining with respect to the test of transmission probabilities, and the rejection of mendelian transmission was due to a single family in the recessive case, instead of several families in the codominant one. This could possibly explain why previous studies, all using the mixed model, found evidence for a recessive major gene. Although the major gene hypothesis cannot be definitely ruled out from our results, the mechanism appears more complex than the effect of one single gene.

[The epidemiology of asthma in Lorraine. A method of Study (author's transl)]. / Epidémiologie de l'asthme en lorraine recherche méthodologique.

The authors undertook an epidemiological study to held useful criteria to identify asthma sufferers. A simple questionnaire was used asking three questions: - Do you wheeze on breathing? - Do you have attacks of breathlessness during the night? - Do you have asthma? 7,904 people were questioned at the Centre for Preventive Medicine at Vandoeuvre-les-Nancy over a year and 1,062 gave a positive response to at least one question. The replies were sub-divided into 5 groups according to the pattern of response and were then given a further clinical assessment as follows: - A sensitivity test for house dust allergy; - A bronchial sensitivity test to Acetylcholine; - The level of blood eosinophilia; - Presence or absence of a family history of asthma. The results were then compared to a matched group of controls who gave a negative reply to all three questions. The authors concluded that the term asthma should only be used by people who recognize themselves as asthmatics and can identify at least one trigger factor in their symptoms. One frequently finds in such people : a family history of asthma, a positive allergy test to the house dust mite, and eosinophilia. On the other hand those with only one or two symptoms (dyspnoea or wheezing) without recognizing themselves as asthmatics had little evidence of a family history of asthma, a sensitivity to the house dust mite comparable to controls and no eosinophilia; in these people there was a striking relationship to tobacco consumption. The Acetylcholine test shows little discriminative value in an epidemiological study of this nature; asthmatics could not be separated from patients with chronic air-flow obstruction, particularly when due to tobacco. It would be helpful to find a test of bronchial hyperactivity which could be used epidemiology. As a result of this study it is possibly to place the prevalence of asthma in the South of Lorraine in the range of 1.7 to 3.6% of the population.