Abstract
The digestive system includes the structures and organs involved in processing of foods required for growth, development, maintenance, and body repair. Most diseases affecting this system are due to infections from bacteria, viruses, protozoa, and fungi, while others are hereditary. The ear, nose, and throat (ENT) system is a complex set of structures sharing slightly interrelated mechanisms of operation. While some disorders of the ENT are hereditary, environmental influences play a big role. Diseases that affect eyesight primarily centre on three layers of the eye (sclera, choroid, and retina) which make eyesight possible. Disorders of metabolism occur when a crucial enzyme is disabled, or if a control mechanism for a metabolic pathway is affected. The chapter focuses on 14 diseases with suspected genetic causes including cystic fibrosis, diabetes, glucose-galactose malabsorption, hemochromatosis, obesity, Wilson's Disease, Zellweger syndrome, deafness, Pendred syndrome, Best Disease, glaucoma, gyrate atrophy, male pattern baldness, and Alport syndrome.