Do Different Types of First Cousins Marriage Carry Different risks for Multifactorial Disorders in Children?

Different types of first cousins marriage may variously affect the incidence of multifactorial disorders. Based on the pattern of X chromosome transmission, it seems that parallel and cross - cousin matrilateral marriages can have higher risks of multifactorial disorders with susceptibility genes on X chromosome in comparison to parallel and cross - cousin patrilateral marriages. In this study, the data of patients with 10 multifactorial disorders were extracted from the pedigrees of 9964 genetic counseling files. The frequency of different types of first cousins marriages among the parents of female patients with three disorders - cleft lip/palate, cleft palate, and systemic lupus erythematosus - was compared to the control group. No significant difference was observed in the frequency of different types of first cousins marriages among female patients’ parents and the control group. It seems that more studies are required to compare the effects of different types of first cousins marriages.