Human digestive system digestive system is subject to a wide range of disorders many of which can be congenital. Mouth diseases can also be caused by pathogenic bacteria, viruses, fungi and as a side effect of some medications. Mouth diseases include tongue diseases and salivary gland diseases. A common gum disease in the mouth is gingivitis which is caused by bacteria in plaque. The most common viral infection of the mouth is gingivostomatitis caused by herpes simplex. A common fungal infection is candidiasis commonly known as "thrush" which affects the mucous membranes of the mouth. There are a number of esophageal diseases such
Human disease modifier gene The process proceeds with the identification of modifier loci and functional determination of the mechanisms of their interactions with other disease-causing genes, and culminates with the discovery and development of effective therapeutics for disease, informed by mechanistic understanding of the functions of modifier genes. For skilled researchers using modern techniques, each step in this process of curing human genetic disease by studying modifier gene interactions poses great challenges. Characterizing modifier gene interactions may not be the easiest approach to curing disease. This is certainly true in the case that modifier genes do not exist or functionally contribute to the disease