Describe the use of single-nucleotide polymorphisms (SNPs) in the study of genetic causes of schizophrenia.

Explain the use of single-nucleotide polymorphisms (SNPs) in the study of genetic causes of schizophrenia. Single-nucleotide polymorphisms (SNPs) are variations in a single nucleotide (A, T, C, or G) that occur at specific positions in the human genome and can act as markers for differences between individuals' DNA. They are used to study the genetic basis of complex diseases like schizophrenia, which are caused by multiple interacting genes. Genome-wide association studies (GWAS) help identify genetic variants associated with complex traits and diseases like schizophrenia by genotyping millions of SNPs across the genome in cases (individuals with schizophrenia) and controls (individuals without schizophrenia). Researchers then compare the frequencies of each SNP in the two groups to identify associations between specific SNPs and the disorder. Some examples of SNPs associated with schizophrenia include those in the major histocompatibility complex (MHC) region, ZNF804A, and CACNA1C genes. However, there are challenges in determining the causal relationship between these genetic variants and the disease, as many associated SNPs have small effect sizes and account for only a portion of schizophrenia's heritability. Further research is necessary to uncover the causes and develop better treatment strategies.