Kaposi's sarcoma: A relatively rare type of cancer that develops on the skin of some elderly persons or those with a weak immune system, including those with acquired immune deficiency syndrome (AIDS).

Kartagener's syndrome: The trio of sinusitis, bronchitis and situs inversus (lateral reversal of the position all organs in the chest and abdomen with the heart and stomach on the right, the liver on the left, etc.--opposite or "inverted" from their usual position).

Karyotype: A standard arrangement of the chromosome complement, done for chromosome analysis.

Karyotyping: Chromosome study.

Karyotyping, flow: Use of flow cytometry to analyze and/or separate chromosomes on the basis of their DNA content. Flow cytometry detects the light- absorbing or fluorescing properties of chromosomes passing in a narrow stream through a laser beam and with automated sorting devices can sort successive droplets of the stream into different fractions depending on the fluorescence emitted by each droplet.

Kawasaki’s disease: A syndrome of unknown origin, mainly affecting young children, causing fever, reddening of the eyes (conjunctivitis), lips and mucous membranes of the mouth, ulcerative gum disease (gingivitis), swollen glands in the neck (cervical lymphadenopathy), and a rash that is raised and bright red (maculoerythematous) in a glove-and-sock fashion over the skin of the hands and feet which becomes hard, swollen (edematous), and peels off. Also called mucocutaneous lymph node syndrome.

Kb: Abbreviation for kilobase.

Keloid: A tough raised scar.

Keratin: Protein in the upper layer of the skin, hair, nails and animal horns. The word keratin comes from the Indo-European ker meaning horn.

Keratitis: Inflammation of the cornea (transparent structure at the front of the eye).

Kerato-: A confusing prefix it can refer to the cornea (as in keratitis and keratocornea) or to "horny" tissue (as in keratin and keratosis).

Keratoconjunctitis: Inflammation of the eye involving both the cornea and conjunctiva.

Keratoconus: Cone-shaped cornea with the apex of the cone being forward. Also called conical cornea.

Keratoma: A callus.

Keratoplasty: Corneal transplant.

Keratosis: A localized overgrowth of the upper layer of skin. Common forms of keratosis include aging (senile keratosis) and sun exposure (actinic keratosis).

Keratotomy: A surgical incision (cut) of the cornea. A radial keratotomy is a surgical procedure designed to flatten the cornea and thereby correct myopia (nearsightedness). It is called a radial keratotomy because the incisions resemble the spokes in a bicycle wheel.

Kernicterus: Disorder due to jaundice in a newborn baby with high blood levels of the pigment bilirubin that is deposited in the brain resulting in damage. The level of bilirubin is monitored in newborns to determine whether treatment is needed to prevent kernicterus. With brain affected, it is also called bilirubin encephalopathy.

Keshan disease: Condition caused by deficiency of the essential mineral selenium. Keshan disease is a potentially fatal form of cardiomyopathy (disease of the heart muscle). It was first observed in Keshan province in China and since has been found elsewhere (including New Zealand and Finland) in areas where the selenium level in the soil is low.

Ketoacidosis: Ketosis (accumulation of substances called ketone bodies in the blood) plus acidosis (increased acidity of the blood). Ketoacidosis occurs when diabetes is not controlled.

Kidneys: The kidneys are a pair of organs located in the right and left side of the abdomen which clear "poisons" from the blood, regulate acid concentration and maintain water balance in the body by excreting urine. The urine then passes through connecting tubes called "ureters" into the bladder. The bladder stores the urine until it is released during urination.

Kilobase: Unit of length of DNA equal to 1000 nucleotide bases.

Kindred: The extended family.

Kinky hair syndrome: Genetic disorder with fragile twisted ("kinky") hair and progressive deterioration of the brain. Due to an error in copper transport resulting in copper deficiency. Females are carriers and their sons with the gene have the disease. Also known as Menkes syndrome.

Kinship: Relationship by marriage or, specifically, a blood tie.

Kissing bugs: Insect vectors (carriers) of the parasite (called Trypanosoma cruzi) which causes Chagas' disease (American trypanosomiasis). The reduviid bugs "kiss" people, especially babies, on the lips while they are asleep infecting them with their parasite. Over 20 million people in the Americas have Chagas disease. The parasite can also be transmitted by blood transfusion and cross the placenta during pregnancy to infect the fetus.

Kissing disease: A name for infectious mononucleosis ("mono"), a very common illness caused by the Epstein-Barr virus (EBV). By the time most people reach adulthood, an antibody against EBV can be detected in their blood meaning they have been infected with EBV. The illness is less severe in young children. The infection can be spread by saliva. The incubation period for "mono" is 4 to 8 weeks. Symptoms include fever, fatigue, sore throat, and swollen lymph glands. "Mono" can cause liver inflammation (hepatitis) and spleen enlargement. Vigorous contact sports should be avoided to prevent spleen rupture.

Klebsiella: A group of bacteria normally living in the intestinal tract and frequently the cause of nosocomial infections (infections acquired in the hospital). Named for Dr. Klebs.

Kleeblattschadel: German for cloverleaf skull

Klinefelter syndrome: The most common single cause of hypogonadism (underfunction of the gonads) and infertility in men, Klinefelter syndrome is due to a chromosome abnormality with XXY (plus additional X or Y chromosomes). It affects about 1 in 500 males and results in small testes (hypogenitalism), underproduction of testosterone and infertility (hypogonadism), and a long-limbed, long-trunked, relatively tall, slim build. Klinefelter boys tend to have learning and/or behavioral problems. At adolescence there is little growth of facial hair and a third of boys develop gynecomastia (enlargement of the male breast). Named for the physician Harry Klinefelter who with E.C. Reifenstein, Jr. and Fuller Albright (the founder of modern endocrinology) described the condition in 1942 long before its chromosomal basis became known.

Klippel-Feil sequence/syndrome: The combination of short neck, low hairline at the nape of the neck and limited movement of the head. It is due to a defect in the early development of the spinal column in the neck (the cervival vertebrae).

Klinefelter syndrome: A condition in males due to XXY sex chromosomes (plus sometimes additional X or Y chromosomes) resulting in small testes, insufficient production of testosterone, and infertility. Klinefelter boys tend to have learning and/or behavioral problems.

Knee: See genu.

Knee bursitis: A bursa is a fluid-filled sac that functions as a gliding surface to reduce friction between moving tissues of the body. There are three major bursae of the knee. Bursitis is usually not infectious, but the bursa can become infected. Treatment of non-infectious bursitis includes rest, ice, and medications for inflammation and pain. Infectious bursitis is treated with antibiotics, aspiration, and surgery.

Knee jerk: The reflex tested by tapping just below the bent knee on the patellar tendon to cause the quadriceps muscle to contract and bring the lower leg forward. It has given rise to the saying: a knee-jerk reaction. Also known medically as the patellar reflex.

Knock-knees: In medicalese: there are no knock-knees. The condition is genu valgum.

Knuckle: The dorsal aspect of the flexed metacarpophalangeal joint. Knuckle may be shorter and simpler to say.

Krukenberg tumor: A tumor of the ovary caused by the spread of stomach cancer.

Kuru: A slowly progressive fatal disease of the brain (a form of subacute spongiform encephalopathy) due to an infectious agent (a virus or subviral particle called a prion) transmitted among people in Papua New Guinea by ritual canabalism. The discovery of the basis of Kuru is one of the more interesting detective stories of 20th-century medicine.

Kussmaul breathing: Air hunger.

Kwashiorkor: The word kwashiorkor comes from the Ivory Coast. It means the deposed (no longer suckled) child. Kwashiorkor is a childhood disease due to protein deprivation. Early signs are vague: apathy (indifference), lethargy (drowsiness) and irritability. More advanced signs are poor growth, lack of stamina, loss of muscle mass, swelling, abnormal hair (sparse, thin, often streaky red or gray in dark-skinned children) and abnormal skin (darkening in irritated but not sun-exposed areas). Kwashiorkor disables the immune system so the child is susceptible to a host of infectious diseases. Kwashiorkor is responsible for much morbidity (illness) and mortality (death) among children worldwide. Also known as protein malnutrition. and protein-calorie malnutrition (PCM).

Kyphoscoliosis: Combination of kyphosis and scoliosis (lateral curving of the spine). Part of good health maintenance is to check a child's back (from infancy through adolescence) to make sure the back looks normal and, if concerned, a doctor is consulted.

Kyphosis: Humpback.