Genetic Risk Factors and Environmental Moderators of Schizophrenia in Families with Multiplex Psychiatric History in North West Nigeria

Schizophrenia has substantial heritability, yet the interplay between genetic risk and environmental moderators such as cannabis use, urban birth, and childhood trauma has not been explored in Nigerian multiplex families. This study examines genetic risk markers and environmental moderators of schizophrenia among families with multiplex psychiatric history in Kano and Sokoto States, North West Nigeria. A family-based case-control design will recruit 80 probands with confirmed schizophrenia from multiplex families (two or more affected first-degree relatives) and 80 unaffected family members as controls. Whole blood samples will be collected for genomic DNA extraction and genotyping of established schizophrenia risk loci (22q11.2, DISC1, COMT Val158Met). Environmental exposure data including cannabis use, birth complications, childhood trauma (CTQ-SF), and urban-rural birth location will be collected via structured interview. Gene-environment interaction analyses will use regression modeling with interaction terms. This study advances Nigerian psychiatric genetics research, which has largely been limited by resource constraints. Findings will contribute to risk profiling models for schizophrenia in West African populations and support the development of genetic counseling resources. Keywords: schizophrenia, genetic risk, gene-environment interaction, multiplex families, North West Nigeria