High Concordance of Bipolar I Disorder in a Nationwide Sample of Twins

Abstract

The high heritability of bipolar disorder was demonstrated in a nationwide population-based twin sample assessed with structured personal interviews.

Analysis of the neuroligin 3 and 4 genes in autism and other neuropsychiatric patients

“…Indeed, this case-control design cannot a priori distinguish full from partial penetrance. In addition, the epidemiological and biological context of our work is consistent with the interpretation that missense variants with incomplete penetrance predispose to autism as follows: (i) incomplete penetrance is the rule in psychiatric diseases (eg BPD, schizophrenia, autism) as the concordance (or concordance for disease spectrum phenotypes) found in monozygotic twins can vary from 43 to 92% and typically is 15% or lower in dizygotic twins who share similar environment and half of the genes; [9][10][11] (ii) the strict conservation of V403 in the five members of the neuroligin family (representing 2 þ billion years of evolutionary divergence 12,13 ) suggests that amino-acid substitution at V403 is deleterious; (iii) the affected sibs have V403M, consistent with a single genetic mechanism as generally expected in a single family with this uncommon disease (0.2% incidence) and (iv) the current case-control studies complement the data of Jamain et al 1 and Laumonnier et al 2 that strongly suggest protein-truncating mutations predispose to autism. Efforts are underway to ascertain extended families of the four probands and to characterize them clinically and genetically.…”

Toward stratified treatments for bipolar disorders

“…Genetic factors constitute approximately 90% of bipolar I disorder causes (Kieseppa et al, 2004;McGuffin et al, 2003). However, identification of individual risk genes is still unsuccessful.…”

Expression profiling in monozygotic twins discordant for bipolar disorder reveals dysregulation of the WNT signalling pathway

“…1 The increased concordance rates between monozygotic (MZ) twins compared to dizygotic (DZ) twins for BD is a major line of evidence, implicating genetic risk factors. BD concordance rates between MZ twins vary between 43 and 79%, 2,3 with high estimates of heritability being reported (89 4 -93% 3 ).…”