[Genetic epidemiology and psychiatry (I): scope and limitations of familial studies. Case of panic disorder].
Genetics epidemiology shed new light on multifactorial disorders for which genes are partly involved, for example on numerous psychiatric diseases. Nevertheless, each epidemiological technic has it's caracteristics and limitations. This review discuss the impact of aggregation studies, on the bases of an example, namely all aggregation studies on panic disorder. We detected through Medline thirteen studies, comparing 3,700 relatives of 780 probands affected with panic disorder, with 3,400 relatives of 720 unaffected controls. It is computed that relatives of patients with panic disorder have an increased risk (10.7%) for panic disorder than relatives of controls (1.4%), relatives from affected probands having a high relative risk (6.8) for panic disorder according to the meta-analysis. On the basis of these 13 aggregation studies, there is an important attribuable risk (78.3%) of "having a familial history of panic disorder" in the risk for panic disorder. Furthermore, the estimated heritability is 73% (73% of the total variance would be explained by additive genetic effects), if Reich's conditions are fulfilled for a valid estimation of the heritability on the basis of aggregation families. These studies can also be used to highlight the variability of expression according to gender, to show the relevance of quantitative approaches (versus the qualitative approach which is nearly systematically used), to underline the informations raised by experimental technics (such as panic disorder induced by lactate), and to raise the potential existence of phenocopies. Lastly, aggregation studies on panic disorder can help to understand the high comorbidity of this disorder, with other anxiety disorders and mood disorder.
Gorwood
P
P
Service de Psychiatrie Adulte, Hôpital Louis Mourier, Colombes.
Feingold
J
J
Ades
J
J
D005260:Female; D006801:Humans; D008297:Male; D008957:Models, Genetic; D016584:Panic Disorder / Q000453:epidemiology* / Q000235:genetics*; D010641:Phenotype; D011570:Psychiatry