Disease resistance is a critical trait that plays a crucial role in the survival and fitness of animal populations. Understanding the genetic basis of disease resistance is essential for managing and mitigating the impacts of disease outbreaks in both wild and captive animal populations. In this study, a review of existing literature was conducted to investigate the genetic basis of disease resistance in animal populations. The review focused on the major histocompatibility complex (MHC) and other genes involved in the immune response. The review found that the genetic basis of the immune response is determined by the animal's genetic makeup, with many different genes and pathways involved. The specific genes involved can vary between species and populations. However, common genes and pathways across different animal species indicate the existence of common mechanisms underlying disease resistance. The study identified several genes and pathways associated with disease resistance, including those involved in the production of immune cells, cytokines, and antimicrobial peptides. Additionally, the review highlighted the role of the MHC in shaping the immune response and disease resistance in animal populations. Furthermore, the review identified several gaps in our understanding of the genetic basis of disease resistance in animal populations. There is a need for more research on the genetic basis of disease resistance in many wild animal species, as well as more research on the interactions between genetic and environmental factors in shaping disease resistance.