Abstract
Most studies underline the contribution of heritable factors for psychiatric disorders. However, heritability estimates depend on the population under study, diagnostic instruments, and study designs that each has its inherent assumptions, strengths, and biases. We aim to test the homogeneity in heritability estimates between two powerful, and state of the art study designs for eight psychiatric disorders. We assessed heritability based on data of Swedish siblings (N = 4 408 646 full and maternal half-siblings), and based on summary data of eight samples with measured genotypes (N = 125 533 cases and 208 215 controls). All data were based on standard diagnostic criteria. Eight psychiatric disorders were studied: (1) alcohol dependence (AD), (2) anorexia nervosa, (3) attention deficit/hyperactivity disorder (ADHD), (4) autism spectrum disorder, (5) bipolar disorder, (6) major depressive disorder, (7) obsessive-compulsive disorder (OCD), and (8) schizophrenia. Heritability estimates from sibling data varied from 0.30 for Major Depression to 0.80 for ADHD. The estimates based on the measured genotypes were lower, ranging from 0.10 for AD to 0.28 for OCD, but were significant, and correlated positively (0.19) with national sibling-based estimates. When removing OCD from the data the correlation increased to 0.50. Given the unique character of each study design, the convergent findings for these eight psychiatric conditions suggest that heritability estimates are robust across different methods. The findings also highlight large differences in genetic and environmental influences between psychiatric disorders, providing future directions for etiological psychiatric research.
Highlights
Psychiatric disorders place an enormous burden on medical resources and society in general (Eaton et al, 2008; Petrou et al, 2010)
The aim of this study is to provide a test of the homogeneity in heritability estimates between family-based data (h2-national) and single nucleotide polymorphisms (SNP)-based data for eight psychiatric conditions
To ensure that the younger sibling in each pair had lived long enough to receive a potential diagnosis, pairs in which the younger sibling was younger than 5, 10, or 15 years old (BIP and SCZ) were excluded
Summary
Psychiatric disorders place an enormous burden on medical resources and society in general (Eaton et al, 2008; Petrou et al, 2010). Twin studies showed that genetic factors play an important role in the etiology of psychiatric traits. Heritability estimates (h2, i.e. the inherited contribution of genetic variance to trait variance) range from 35% for major depression to over 60% for schizophrenia (SCZ) (Polderman et al, 2015). The remaining variance is explained by non-genetic factors perhaps including non-identifiable environmental factors Another method to derive estimates of genetic and environmental variance is the use of pedigree data (e.g. parents and children, siblings and half-siblings) from large national registers (Pettersson et al, 2016). Most studies underline the contribution of heritable factors for psychiatric disorders. Eight psychiatric disorders were studied: (1) alcohol dependence (AD), (2) anorexia nervosa, (3) attention deficit/hyperactivity disorder (ADHD), (4) autism spectrum disorder, (5) bipolar disorder, (6) major depressive disorder, (7) obsessive-compulsive disorder (OCD), and (8) schizophrenia. When removing OCD from the data the correlation increased to 0.50
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a call
