Our body is a machine for living. It is organized for that, it is its nature. Let life go on in it unhindered and let it defend itself, it will do more than if you paralyze it by encumbering it with remedies.
— Leo Tolstoy, War and Peace

Biological Disorders: disturbances of the normal state of the body or mind. Disorders of structure or function in an animal or plant. (Oxford) Disorders may be caused by genetic factors, disease, or “trauma.” (NCI3)

All animals must contend with various threats within their internal environment, including the invasion of potentially harmful "microorganisms," such as "bacteria," the presence of foreign molecules, and the presence of abnormal cells. (Booker, 1127)


Albinism: a “congenital” disorder characterized by partial or complete absence of “melanin”  “pigment” in the eyes, hair and skin. (NCIt) One “gene” “codes” for the production of pigment and another gene codes for the precise color of pigment. If the gene that promotes pigment production is absent or inactive, then no pigment of any color is made, leading to the ‘albino’ "phenotype." (Mikulecky, 233) A person with albinism will have symptoms (that may include) absence of color in the hair, skin, or iris of the eye, lighter than normal skin and hair, or patchy, missing skin color. (PubMedHealth2) Editor’s note - albinism is an example of “epistasis.”

Anemia: a condition in which the body does not have enough healthy "red blood cells." Red blood cells provide “oxygen” to body “tissues.” (PubMedHealth2) The number of red blood cells is below normal. Clinically, anemia represents a reduction in the oxygen-transporting capacity of a designated volume of blood, resulting from an imbalance between blood loss and blood production. Signs and symptoms of anemia may include (unusual paleness) of the skin and “mucous membranes,” shortness of breath, “palpitations” of the heart, “lethargy,” and (“fatigue”). (NCIt)

Anoxia: a condition in which the tissues of the body receive inadequate amounts of oxygen. (OxfordMed) Manifestation of “respiratory” distress consisting of a relatively complete absence of oxygen. (MeSH)

Asthma: chronic disease in which contractions of the “airways,”  “inflammation,” and accumulation of “mucus” block air flow. (Lewis, 337) Asthma is a disease that causes the airways of the lungs to swell and narrow, leading to wheezing, shortness of breath, chest tightness, and coughing. (PubMedHealth2) A form of bronchial disorder with three distinct components: airway ‘hyper-responsiveness,’ airway inflammation, and intermittent airway obstruction. It is characterized by ‘wheezing.’ (MeSH)

Autoimmune Disorders: disorders that are characterized by the production of antibodies that react with host tissues. (MeSH) A condition that occurs when the immune system mistakenly attacks and destroys healthy body tissue. There are more than 80 different types of autoimmune disorders. (PubMedHealth2) Some are “single-gene inherited,” but not most. Some may result from the actions of "variants" of several genes. Some may result from an overactive immune response. (Lewis, 336)

Autosomal Dominant Disorder: a pattern of “inheritance” characteristic of some “genetic diseases.”  "Autosomal" means that the gene in question is located on one of the non-sex chromosomes. "Dominant" means that a single copy of the disease-associated “mutation” is enough to cause the disease. This is in contrast to a “recessive” disorder, where two copies of the mutation are needed to cause the disease. “Huntington's disease” is a common example of an autosomal dominant genetic disorder. (NHGRI)

Blood Clot: a mass of blood that forms when blood “platelets,” proteins, and cells stick together. (NCIt) Clumps that occur when blood hardens from a liquid to a solid. Can partly or completely block the flow of blood in a “blood vessel.” A blockage in an “artery” may prevent oxygen from reaching the tissues in that area. A blockage in the “vein” will usually cause fluid buildup and swelling. Situations in which a blood clot is more likely to form include being on long-term bed rest, crossing legs for long periods of time when sitting, or sitting for long periods of time, such as in a plane or car, and not having enough water in your body (dehydration). Blood clots are also more likely in people with "cancer," recent surgery or injury, obesity, and "liver" or "kidney" disease. A buildup of “cholesterol” that narrows an artery may change or slow the flow of blood, making it easier for a blood clot to form. (PubMedHealth2) Also referred to as ‘thrombus.’

Embolus: (blood clot that) moves through the bloodstream and blocks the flow of blood in another part of the body. (NCIt) A “thrombus” that breaks loose and travels from one location in the body to another. (PubMedHealth2)

Blue Person Disease: a bluish color to the skin or mucus membranes that is usually due to a lack of oxygen in the blood. Red blood cells provide oxygen to body tissues. Most of the time, almost all red blood cells in the arteries carry a full supply of oxygen. These blood cells are bright red and the skin has a pinkish or red hue. Blood that has lost its oxygen is dark bluish-red. People whose blood is low in oxygen tend to have a bluish color to their skin, called ‘cyanosis.’ (PubMedHealth2) Excess oxygen-poor hemoglobin causes a dark blue complexion. Carriers may have bluish lips and fingernails at birth, which usually improve. Simple treatment - a tablet of ‘methylene blue,’ a commonly used dye, converts back to normal hemoglobin. (Lewis, 227)

Carpal Tunnel Syndrome: a condition in which there is excessive pressure on the 'median' nerve. This is the nerve in the wrist that allows feeling and movement to parts of the hand. Carpal tunnel syndrome can lead to numbness, tingling, weakness, or muscle damage in the hand and fingers. (PubMedHealth2) Caused when repetitive hand motions lead to a ‘shearing’ injury in the tissue that lines the tendons in the wrist or forearm. (Blakeslee, 192)

Cholera: infection of the small intestine. Caused by the bacterium ‘Vibrio cholerae.’ The bacteria releases a “toxin” that causes increased release of water from cells in the intestines, which produces severe diarrhea. Cholera occurs in places with poor sanitation, crowding, war, and famine. People get the infection by eating or drinking contaminated food or water. (PubMedHealth2) Due to its “cytotoxicity,” cholera toxin is being studied for “tumor” cell targeting and cancer “chemotherapy.” (NCIt)

Chronic: describing a disease of long duration involving very slow changes. Such disease is often of 'gradual onset' (comes on slowly). The term does not imply anything about the severity of a disease. (OxfordMed) Something that continues over an extended period of time. A chronic condition is usually long-lasting and does not easily or quickly go away (PubMedHealth2)

Coma: a clinically defined condition, in which the patient cannot be aroused, and shows no evidence of conscious sensation, reflexes, or any significant movement. (Koch, 332) A condition in which a patient is in a state of deep sleep and cannot be awakened. A coma may be caused by many things, including trauma, drugs, toxins, or certain diseases. (NCIt)

Complex Diseases: (those) caused by the interaction of multiple genes and environmental factors. Complex diseases are also called 'multifactorial.' Examples of complex diseases include cancer and “heart disease.” (NHGRI) Involves multiple genetic and environmental factors. Obesity, heart disease, and “schizophrenia” are examples of diseases that have multiple causes. (GNN) Also referred to as 'complex disorders.'

Crenation: cell shrinkage or swelling. (Brooker 94) Notched or wrinkled appearance. (Lawrence)

Cystic Fibrosis: a disease passed down through families that causes thick, sticky mucus to build up in the lungs, digestive tract, and other areas of the body. It is one of the most common chronic lung diseases in children and young adults. It is a life-threatening disorder. (PubMedHealth2) The disease affects the cells that produce mucus, sweat, saliva and digestive juices. In a person with cystic fibrosis, these secretions are thick and sticky. Instead of smoothing the surfaces that these secretions are on, they plug up tubes, ducts and passageways, especially in the lungs and pancreas. Respiratory failure is the most dangerous complication of cystic fibrosis. (Cedars-Sinai) Caused by mutations in a gene that is expressed in several organs including the lung, the pancreas, the biliary system (which moves, stores, and releases bile into the duodenum to the body digest foods), and the sweat glands (which are sweat-producing structures that are embedded in the skin). (MeSH) With the mutation, a protein never makes it to the cell membrane to assume its proper place as a channel protein. (Lewis, 27) As a result the cell excretes out too much salt, and too little water. This results in a sticky mucus that clogs the lungs and (also) extra salt in the patient's sweat. (Micklos, 293) An estimated 1 in 29 Caucasian Americans have the CF gene. The disease is the most common, deadly, inherited disorder affecting caucasians in the United States. (PubMedHealth2) Affects the lungs and digestive system of about 30,000 children and adults in the United States and about 70,000 worldwide. About 1,000 new cases of cystic fibrosis are diagnosed each year. More than 70% of patients are diagnosed by age two. More than 45% of the CF patient population is age 18 or older. (CFF)

Degenerative Disease: one in which the function or structure of the affected tissues or organs changes for the worse over time. “Osteoarthritis,”  “osteoporosis,” and “Alzheimer disease” are examples. (NCI1) Caused by deterioration of organs or tissues, rather than by infection. (Lawrence) Characterized by progressive, often irreversible... loss of function. (Oxford)  Also referred to as ‘degenerative disorder.’

Dehydration: a condition caused by the loss of too much water from the body. Severe diarrhea or vomiting can cause dehydration. (NCIt) The body does not have as much water and fluids as it should. Dehydration can be mild, moderate, or severe based on how much of the body's fluid is lost or not replenished. When it is severe, dehydration is a life-threatening emergency. Dehydration can be caused by losing too much fluid, not drinking enough water or fluids, or both. (PubMedHealth2)

Disease: a disorder with specific cause and recognizable signs and symptoms. (OxfordMed) In medicine, a health problem with certain characteristics or symptoms. (NCIt) A definite pathologic process with a characteristic set of signs and symptoms. It may affect the whole body or any of its parts, and its “etiology,”  “pathology,” and “prognosis” may be known or unknown. (MeSH)

Disorder: any abnormal condition of the body or mind that causes discomfort, dysfunction, or distress to the person affected or those in contact with the person. The term is often used broadly to include injuries, disabilities, syndromes, symptoms, deviant behaviors, and atypical variations of structure and function. (NCIt)

Familial Hypercholesterolemia: a disorder of high “LDL cholesterol” that is inherited. The condition begins at birth and can cause “heart attacks” at an early age. (PubMedHealth2) (Caused by a) reduced number of ... “receptors” (on liver cells) that take up “cholesterol” from the bloodstream. Results in a buildup of cholesterol in arteries. (Lewis, 221) An example of “incomplete dominance” in humans. Those with two "mutant" “alleles” die in childhood of heart attacks, those with one mutant allele may suffer heart attacks in young adulthood, and those with normal alleles do not develop this inherited form of heart disease. (Lewis, 92)

Fatigue: a condition marked by extreme tiredness and inability to function due lack of energy. Fatigue may be acute or "chronic." (NCIt) A feeling of weariness, tiredness, or lack of energy. Fatigue can be a normal and important response to physical activity, emotional “stress,” boredom, or lack of sleep. Fatigue is a common symptom, and it is usually not due to a serious disease. But it can be a sign of a more serious mental or physical condition. (PubMedHealth2)

Fever: a rise in body temperature above the normal, i.e. above an oral temperature of 98.6 degrees F, or 37 degrees C. Fever is generally accompanied by shivering, headache, nausea, constipation, or diarrhea. Fevers are usually caused by "bacterial" or "viral infections," and can accompany an "infectious" illness, from the common cold to "malaria." (OxfordMed)

Fragile X Syndrome: a genetic condition involving changes in part of the X chromosome. It is the most common form of inherited intellectual disability in boys. Behavior problems associated with fragile X syndrome include delay in crawling, walking, or twisting, hand clapping or hand biting, and/or speech and language delay. Physical signs may include large body size, large forehead or ears with a prominent jaw, and long face. (PubMedHealth2) A “triplet” repeat mutation. Contains about 30 repeats of the “sequence” CGG in a gene called ‘fragile X mental retardation gene.' Tips at one “X-chromosome” end dangle by a thin thread. Very prone to breaking - hence the name ‘fragile X.’ Most commonly inherited form of intellectual disability. Worldwide affects 1 in 2,000 males accounting for 4% to 8% of all males with intellectual disability. 1 in 4,000 females is affected with usually a milder case. Accounts for 3% of cases of “autism spectrum disorder.” (Lewis, 224)

Gaucher Disease: a rare genetic disorder in which a person lacks an enzyme called ‘glucocerebrosidase.’ Affects an estimated 1 in 50,000 to 1 in 100,000 people in the general population. Persons of Eastern and Central European (Ashkenazi) Jewish heritage are more likely to get this disease. It is an autosomal recessive (which) means that the mother and father must both pass one abnormal copy of the gene to the child in order for the child to develop the disease. (PubMedHealth2) A “lysosomal” storage disease. (Lewis, 395) Caused by an “insertion” mutation. An inserted single DNA base prevents production of an enzyme that normally breaks down “glycolipid" in lysosomes. The resulting buildup of glycolipid enlarges the liver and “spleen” and causes easily fractured bones and neurological impairment. (Lewis, 221)

Generalized: widespread, broadly dispersed, common. (NCIt)

Hemophilia: a hereditary bleeding disorder caused by a lack of ‘blood clotting factor VIII.’ Without enough factor VIII, the blood cannot “clot” properly to stop bleeding. The most common treatment is to replace the missing clotting factor in the blood through a vein (‘intravenous infusion’). (PubMedHealth2) The responsible gene is located on the X chromosome, and since males inherit only one copy of the X chromosome, if that chromosome carries the mutated gene, they will have the disease. Females have a second, usually normal, copy of the gene on their other X chromosome, so they are capable of passing on the disease without experiencing its symptoms. (NHGRI) An X-Linked Trait. “Incidence” is 1 in 10,000 male births. Incidence is 1 in 100 million female births. (Lewis, 265)

Hemorrhage: medical term for bleeding, usually excessive bleeding. Hemorrhagic diseases are caused by, or result in, bleeding (hemorrhaging). (PubMedHealth2) Adjective - 'hemorrhagic.'

Idiopathic: of a disease: not consequent on or symptomatic of another disease; having no known cause. (Oxford)

Immunodeficiency: the decreased ability of the body to fight infections and other diseases. (NCI1) A disorder in which the “immune system” is unable to mount an adequate “immune response.” (NCIt) Any deficiency in the ability to mount an effective immune response. It may be due to various causes, such as the destruction of a class of “Helper T cells” in “AIDS” … or the non-development of “lymphocytes” due to various genetic defects. (Lawrence)

Inborn Errors of Metabolism: genetic disorders that result from deficient or absent enzymes. (Lewis, 21) Disorders in which the body cannot properly turn food into energy. The disorders are usually caused by defects in specific proteins (enzymes) that help break down (“metabolize”) parts of food. (PubMedHealth2)

Inflammation: redness, swelling, pain, and/or a feeling of heat in an area of the body. This is a protective reaction to injury, disease, or irritation of the tissues. (NCIt) ‘Acute inflammation’ is the immediate defensive reaction of tissue to any injury, which may be caused by infection, chemicals, or physical agents. It involves pain, heat, redness, swelling, and loss of function of the affected part. Blood vessels near the site of injury are dilated, so that blood flow is locally increased. "White blood cells" enter the tissue and begin to engulf “bacteria” and other foreign particles. Similar cells from the tissues remove and consume the dead cells. (OxfordMed)

Lesion: characteristic damage to an organ or tissue caused by disease processes. (Bynum 292) A localized pathological or traumatic structural change, damage, deformity, or discontinuity of tissue, organ, or body part. An area of abnormal tissue. A lesion may be benign (not cancer) or malignant (cancer). (NCIt) ‘Primary' lesions include “abscesses,”  “ulcers,” and “tumors.” ‘Secondary' lesions’ include crusts and “scars.” (OxfordMed)

Sinusitis: an acute or chronic infectious process affecting the mucous membranes of the ‘paranasal sinuses.’ (NCIt) Inflammation of one or more of the mucous-membrane-lined air spaces in the facial bones that (connect) with the nose. Often associated with inflammation of the nasal lining. May be acute or chronic. Many cases are “self-limiting.” Others require treatment with "antibiotics," decongestants, or steroid nose drops.  (OxfordMed)

Lethargy: a condition marked by drowsiness and an unusual lack of energy and mental alertness. It can be caused by many things, including illness, injury, or drugs. (NCIt) Adjective - ‘lethargic.’

Lupus: a connective tissue chronic inflammatory disorder affecting the skin, joints, kidneys, lungs, heart, and the peripheral blood cells. (NCIt)  An autoimmune disease in which the body's immune system mistakenly attacks healthy tissue. It can affect the skin, joints, kidneys, brain, and other organs. More common in women than men, (lupus) may occur at any age, but appears most often in people between the ages of 10 and 50. (PubMedHealth2) Produces autoantibodies that affect connective tissue of many organs. Variants in at least ten different genes can cause lupus. Example of an "autoimmune disorder." (Lewis, 336)

Macular Degeneration: a condition (often associated with aging) where the center of the retina in the eye (the 'macula') is damaged, resulting in loss of the center of the visual field so that reading or recognizing faces is impaired, but the peripheral vision is relatively unaffected. (Bynum, 292)

Marfan Syndrome: a disorder of connective tissue, the tissue that strengthens the body's structures. Disorders of connective tissue affect the “skeletal system,”  “cardiovascular system,” eyes, and skin. Caused by defects in a gene called ‘fibrillin-1.’ Fibrillin-1 plays an important role as the building block for connective tissue in the body. The gene defect also causes too much growth of the long bones of the body. This causes the tall height and long arms and legs seen in people with this syndrome. (PubMedHealth2) Autosomal dominant condition. Symptoms are lens dislocation, long limbs, spindly fingers, and a caved-in chest. Most serious symptom is a life-threatening weakening in the "aorta," which can suddenly burst. Whether or not Abraham Lincoln had Marfan syndrome is a matter of debate. A physician diagnosed the president, based on body proportions and a sunken chest. A distant Lincoln cousin had Marfan. (Lewis, 95)

Mendelian Disorders: diseases caused by a single gene that is inherited in a straightforward manner from parent or parents to child. “Huntington’s disease” and cystic fibrosis are examples. Compared to complex inheritance diseases, Mendelian disorders are relatively rare. (GNN) Also referred to as 'single-gene disorder.'

Meningitis: a disorder characterized by acute inflammation of the meninges of the brain and/or spinal cord. (NCIt) Most common causes of meningitis are viral infections that usually get better without treatment. However, bacterial meningitis infections are extremely serious, and may result in death or brain damage, even if treated. (PubMedHealth2) An inflammation of the “meninges” due to infection by viruses or bacteria or fungi. Causes an intense headache, fever, loss of appetite, intolerance to light and sound, rigidity of muscles, especially those in the neck, and in severe cases convulsions, vomiting, and delirium leading to death. (OxfordMed)

Migraine: neural condition characterized by a severe recurrent “vascular” headache, usually on one side of the head, often accompanied by nausea and vomiting. (PubMedHealth2) A common, severe type of vascular headache often associated with increased sympathetic activity, resulting in nausea, vomiting, and light sensitivity. (NCIt) Two major subtypes are ‘common’ migraine (without “aura”) and ‘classic’ migraine (with aura or “neurological” symptoms). (MeSH)

Myalgia: painful sensation originating from a muscle or group of muscles. (NCIt)

Fibromyalgia: a chronic disorder of unknown “etiology” characterized by pain, stiffness, and tenderness in the muscles of (the) neck, shoulders, back, hips, arms, and legs. Other signs and symptoms include headaches, fatigue, sleep disturbances, and painful “menstruation.” (NCIt) The cause is unknown. (It is) a common syndrome in which a person has long-term, body-wide pain and tenderness in the joints, muscles, tendons, and other soft tissues. Fibromyalgia has also been linked to fatigue, sleep problems, headaches, depression, and anxiety. (PubMedHealth2)

Necrosis: the death of some or all of the cells in an organ or tissue, caused by disease, physical or chemical injury, or interference with the blood supply. (OxfordMed) A cell death process that is morphologically characterized by a gain in cell volume, swelling of “organelles,”  “plasma membrane” rupture and subsequent loss of intracellular contents. (NCIt) Adjective - ‘necrotic.’ Also referred to as ‘mortification.’

Osteoarthritis (OA): a (degenerative) disease affecting “joints,” particularly the knee and the hip. The “cartilage” is lost and this may result in damage to the underlying "bone." (Indge, 194) Collagen disorder. Painful joints. Example of a “missense” mutation.  (Lewis, 63) The most common joint disorder. It is mainly related to aging. Often, the cause of OA is unknown. The symptoms of OA usually appear in middle age. Almost everyone has some symptoms by age 70. However, these symptoms may be minor. Before age 55 occurs equally in men and women. After age 55, it is more common in women. Pain and stiffness in the joints are the most common symptoms. The pain is often worse after exercise and when you put weight or pressure on the joint. Cannot be cured. It will most likely get worse over time. However, OA symptoms can be controlled. (PubMedHealth2)

Plaque: in medicine, a small, abnormal patch of tissue on a body part or an organ. Plaques may also be a build-up of substances from a fluid, such as cholesterol in the blood vessels. (NCIt)

Pneumonia: a breathing (respiratory) condition in which there is an infection of the lung. A common illness that affects millions of people each year in the United States. Germs called bacteria, viruses, and fungi may cause pneumonia. In adults, bacteria are the most common cause of pneumonia. (PubMedHealth2) A severe inflammation of the lungs in which the tiny ‘air sacs’ are filled with fluid. This may cause a decrease in the amount of oxygen that blood can absorb from air breathed into the lung. Pneumonia is usually caused by infection but may also be caused by radiation therapy, allergy, or irritation of lung tissue by inhaled substances. It may involve part or all of the lungs. (NCIt)

Polydactyly: a congenital abnormality characterized by more than 5 digits on a hand or foot. (NCIt) Having an abnormal number of digits can occur on its own, without any other symptoms or disease. Polydactyly may be inherited in families. This trait involves only one gene that can cause several variations. (PubMedHealth2) (An example of) “incomplete penetrance.” Some people who inherit the allele have more than five digits on a hand or foot. Yet others have (the normal five). If 80 of 100 people who inherit the dominant polydactyly allele have extra digits, the genotype is (referred to as) '80% penetrant.' (Lewis, 93)

Porphyria Variegata: 'porphyrias' are a group of rare disorders passed down through families, in which an important part of “hemoglobin,” called “heme,” is not made properly. Heme is also found in 'myoglobin,' a protein found in certain muscles. (PubMedHealth2) An autosomal dominant disease that affected several members of the royal families of Europe (including) King George III of England who ruled during the American Revolution. (His multiple symptoms included) abdominal pain, weak limbs, fever, hoarseness, insomnia, headaches, visual problems, delirium, and convulsions. (Lewis, 94)

Presenility: premature aging of the mind and body, so that a person shows the reduction in mental and physical abilities normally found only in old age. (OxfordMed)

Scar: a permanent mark left after a wound healing. (OxfordMed) Scar tissue forms as skin heals after an injury (such as an accident) or surgery. The amount of scarring may be determined by the wound size, depth, and location; the person's age; heredity; and skin characteristics, including color (pigmentation). Not all the factors that affect a scar are completely understood. (PubMedHealth2)

Sepsis: infection of the bloodstream. (Lawrence) Inflammatory response syndrome with a proven or suspected infectious (cause). (MeSH) Severe sepsis is a clinical syndrome defined by the presence of both infection and a systemic inflammatory response that progresses to multi-organ failure. (NCIt) The… destruction of tissues by disease-causing bacteria or their toxins. (OxfordMed) Adjective - ‘septic.’

Skin Rash: any change in the skin which affects its appearance or texture. A rash may be localized to one part of the body, or affect all the skin. Rashes may cause the skin to change color, itch, become warm, bumpy, dry, cracked or blistered, swell and may be painful. (NCIt)

Sickle Cell Disease: a blood disorder characterized by the appearance of sickle-shaped red blood cells and anemia. (NCIt) An example of a “single nucleotide polymorphism” causing disease. A change in one nucleotide base in the coding region for the ‘hemoglobin beta gene’ causes the amino acid ‘glutamic acid’ to be replaced by ‘valine.’ As a result, the hemoglobin molecule can no longer carry oxygen as efficiently because the structure of the protein is changed dramatically. (NCI6, slide 26) The mutation causes the red blood cells to take on an unusual sickle shape. Individuals affected by sickle cell disease are chronically anemic and experience significant damage to their heart, lungs, and kidneys. A hereditary disease seen most often among people of African ancestry. (NHGRI) Inherited from both parents. If you get the sickle cell gene from only one parent, you will have ‘sickle cell trait.’ People with sickle cell trait do not have the symptoms of sickle cell anemia. (PubMed Health2)

Unspecified: not stated explicitly or in detail. (NCIt)