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.
TopChapter Outline
15.1 Overview of Digestive, ENT, and Eye Systems
15.2 Cystic Fibrosis
15.3 Diabetes
15.4 Glucose-Galactose Malabsorption
15.5 Hereditary Hemochromatosis
15.6 Obesity
15.7 Wilson’s Disease
15.8 Zellweger Syndrome
15.9 Deafness
15.10 Pendred Syndrome
15.11 Best Disease
15.12 Glaucoma
15.13 Gyrate Atrophy
15.14 Pattern Baldness
15.15 Alport Syndrome
Chapter Summary
TopLearning Outcomes
- •
Identify each genetic disorder affecting each system
- •
Outline the symptoms of each disorder
- •
Explain the genetic basis of each disorder
- •
Summarize the therapies available to treat each disorder
Top15.2 Cystic Fibrosis (Cf)
CF is considered the most lethal autosomal recessive disorder affecting primarily those of European descent, although it has been reported in all races and ethnicities. CF results in abnormally viscous secretions in the airways of the lungs and in the ducts of the pancreas which cause obstructions leading to inflammation, tissue damage and destruction of both organ systems. Sweat glands, the biliary duct of the liver, the male reproductive tract and the intestine are also often affected. (Cutting, 2015; Deignan & Grody, 2016; Maiuri et al, 2017)
Key Terms in this Chapter
Vitelliform Macular Dystrophy: A genetic form of macular degenerative disease that can cause gradual vision loss.
Hyperbilirubinaemia: Elevated levels of bilirubin in the blood.
Angle-Closure Glaucoma: A rarer form of glaucoma that happens when the iris is not as wide and open as it normally is and blocks the drainage canals causing a quick increase in internal eye pressure.
Osteoarthritis: A joint disease caused by the breakdown of cartilage between bones.
Ataxia: A neurological condition involving the loss of voluntary muscle movement.
Cardiomyopathy: A disease of the heart muscle in which the heart muscle can become thick, enlarged, or stiff.
ACE Inhibitors: A drug used to lower blood pressure and heart failure by reducing the amount of angiotensin II. This allows blood vessels to relax and widen so blood can easily flow through.
Proteinuria: Presence of protein in the urine.
Astigmatism: A refractive error in which the cornea’s curvature is abnormal causing blurry vision.
Aneurysms: A condition that occurs when the artery walls weaken, allowing it to abnormally widen.
Antihistamines: A drug used to relieve symptoms of or prevent allergic reactions.
Triiodothyronine (T3): A thyroid hormone carrying three iodine atoms that regulates basal metabolic rate. T3 is typically formed in the target organs by the removal of an iodine atom from a T4 hormone.
Myopia: A vision disorder in which the eye is too long causing light to focus in front of instead of on the retina—also known as near-sightedness.
Open-Angle Glaucoma: A type of glaucoma that develops slowly and often goes unnoticed. It is when the angle where the cornea meets the iris is normal but there is an increase in internal eye pressure and damage to the optic nerve due to clogging of the eye’s drainage canals.
Thyroxine (T4): A hormone produced only by the thyroid gland that regulates basal metabolic rate carrying four iodine atoms.
Osteoporosis: A disease in which bones become thin and weak.
Chronic Rhinosinusitis: Inflammation of the sinus membranes.
RAAS Blockade: Treatment for renal diseases using angiotensin-converting-enzyme inhibitors.
Intraocular Pressure: Pressure inside the eye.
Bestrophinopathies: A group of five clinically distinct retinal degenerative diseases caused by a mutation in the BEST1 gene.
Albuminuria: Abnormal amounts of albumin present in the urine.
Bardoxolone Therapy: A treatment used for kidney disease that activates signalling pathways that reduce inflammation and improves mitochondrial activity.
Vitreoretinochoroidopathy: An ocular disorder that affects the retina, vitreous, and the choroid and can lead to vision impairment.
Ocular Hypertension: Pressure inside the eye.
Photodynamic Therapy: A therapy used to treat cancer by using a drug called photosensitizing agents and a special kind of light to kill cancer cells.