Background: Minor physical anomalies (MPAs) have been found to be more prevalent in schizophrenia than control participants in numerous studies and may index a potential endophenotype for schizophrenia. Aim: To quantitatively define the magnitude of the difference in total MPA scores between patients with schizophrenia and healthy controls; to determine the degree of manifestation in unaffected first-degree relatives compared to patients and controls; and to investigate the degree of sensitivity among individual MPA items. Methods: A systematic search was conducted on the literature pertaining to MPAs in patients with schizophrenia and unaffected relatives. Effect sizes (Cohen's d and odds ratios) and corresponding confidence intervals were combined using the Comprehensive Meta-Analysis software package. Results: A large difference was found when examining 14 studies comprising 1207 patients with schizophrenia and 1007 healthy controls (d = 0.95, 95% CI = 0.63, 1.27). Six studies involving relatives of individuals with schizophrenia showed a medium effect size (d = 0.45, 95% CI = 0.29,0.62) between patients and relatives, but a small and non-significant effect size (d = 0.32, 95% CI = -0.08, 0.73) between relatives and controls. The majority of MPAs items showed significant odds ratios (1.26-9.86) in comparing patients and controls. Conclusions: The findings indicate that medium effect size of MPAs have been demonstrated in patients with schizophrenia as compared to healthy controls, and to a lesser extent in unaffected relatives. These findings are consistent with the idea that MPAs may represent a putative endophenotype for schizophrenia. However, more research including first-degree family members is warranted. © 2011 Xu et al.
Xu, T., Chan, R. C. K., & Compton, M. T. (2011). Minor physical anomalies in patients with schizophrenia, unaffected first-degree relatives, and healthy controls: A meta-analysis. PLoS ONE, 6(9). https://doi.org/10.1371/journal.pone.0024129