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BIO170 - Obj 10, 11
| Question | Answer |
|---|---|
| What are encephalopathies? | any disorders that relate to CNS or damages the brain |
| What are the 2 types of inherited metabolic disorders? | 1) defects in amino acid metabolism; ex: phenylketonuria (PKU) - a disorder which causes hyperphenylalaninemia; 2) defects in lipid metabolism, such as are found in lysosomal storage diseases such as Tay-Sachs disease |
| What is the etiology of PKU? | it is an autosomal recessive disorder caused by a single-gene defect -> the deficiency of the liver enzyme phenylalanine hydroxylase which is critical for the breakdown of the amino acid phenylalanine |
| What is the pathogenesis of PKU? | lack of the phenylalanine hydroxylase enzyme -> phenylalanine is not broken down -> it accumulates in the blood -> excreted in the urine |
| What are the manifestations of PKU? | accumulation of phenylalanine and its byproducts -> damage to child's nervous system: motor delays, seizures, mental retardation, behavioral disorders, hyperactivity; also very light skin, hair, and eye color |
| What causes the very light skin, hair, and eye color in PKU patients? | normally phenylalanine is converted to tyrosine and then to melanin; absence of the enzyme phenylalanine hydroxylase -> reduced tyrosine -> reduced melanine -> very light skin, hair, eye color |
| What is the treatment for PKU? | dietary restriction of phenylalanine begun as early as diagnosis; successful, early treatment allows near-normal development |
| What happens if PKU is not treated? | neurological damage is progressive and severe |
| What is the etiology of Tay-Sachs disease? | it is an autosomal recessive disorder most common in Jewish populations; it is a lysosomal storage disease, caused by a genetic deficiency in a lysosomal enzyme |
| What is the pathogenesis of Tay-Sachs disease? | lipids accumulate in the lysosomes of neurons -> neurons balloon; axon & myelin sheath degenarate; microglial (phagocytic) cells in the brain proliferate, and the cerebral hemispheres atrophy |
| What are the manifestations of Tay-Sachs disease? | the disease begins to manifest at 3-6 months of age: hypotonic reflexes, seizures, an excessive startle response, loss of developmental milestones |
| What is the treatment for Tay-Sachs disease? | there is no treatment or cure; death typically occurs by age 3 |
| What disease is an inherited disorder of erythrocytes? What disorders are encompassed by this disease, and which is most serious? | sickle cell disease is an inherited disorder of erythrocytes; the disease is expressed as sickle cell anemia, the most severe form, sickle cell-thalassemia disease, or sickle cell-Hb C disease |
| What are the acute manifestations of sickle cell anemia? (4) | 1) vasoocclusive crisis (thrombotic crisis); 2) aplastic crisis; 3) sequestration crisis; and 4) hyperhemolytic crisis |
| What is the major characteristic of all sickle cell disease? What is the mutation? | sickle cell disease disorders are characterized by the presence of an abnormal hemoglobin: Hgb S; the mutation causes valine to be replaced by glutamic acid |
| What happens to the RBCs in sickle cell disease? | deoxygenation and dehydration cause the red cells to solidify and stretch into an elongated sickle shape |
| What is the etiology of sickle cell disease (i.e. anemia)? for sickle cell trait? | for both the disease and trait, it is an autosomal recessive disorder; for sickle cell disease, the patient is homozygous (aa); for sickle cell trait, the patient is heterozygous (Aa) and is phenotypically normal |
| In which geographical area, or in which groups of people is sickle cell disease found? | it can be found in the Mediterranean area, central Africa, Asia, and India; in the US it is most common amont African-Americans |
| Is there any advantage to having sickle-cell trait? | having the sickle-cell trait, the person is phenotypically normal and is less susceptible to malaria which is common in equatorial regions (malaria parasites can't reproduce easily in the blood of a person w/sickle-cell trait) |
| What is the pathogenesis of sickle cell disease? | normal hemoglobin in red blood cells is replaced by hemoglobin S -> hypoxia/stresses turn hemoglobin into a semisolid gel -> RBC becomes irregular and crescent-shaped, like a sickle |
| Describe the sickled cell: | sickled cells are stiff and fragile; they are easily ruptured and destroyed as they pass through tiny capillaries or the spongy spleen or other organs; they cause extreme pain |
| What are the manifestations of sickle cell disease? | profound hemolytic anemia, pallor, fatigue, jaundice, splenomegaly; subject to sickle-cell crises in which the microcirculation oto a specific part of the body is blocked by stiff, sickled cells causing infarcation and death of the tissue |
| What other problems are more likely to occur during a sickle-cell crisis? | frequent infections, kidney damage, heart attack, or stroke |
| How is sickle-cell disease treated/cured? | medications can prevent sickle-cell crises and treat the other symptoms of sickle-cell anermia; there is no cure |
| What is the etiology of Huntington's disease? | aka Huntington's chorea (because of the jerky involuntary movements caused by the disease)it is an autosomal DOMINANT disorder, due to a defect on the short arm of chromosome 4 |
| When is the typical onset of the disease and whom does it effect? | onset is typically around ages 35-50; it occurs in people of all races |
| What is the pathogenesis of Huntington's disease? | causes progressive degeneration of the basal ganglia and frontal lube, and destruction of the neurons which produce GAPA (an inhibitory neurotransmitter) |
| What are the manifestation of Huntington's disease? | begins w/abnormal, spasmodic, choreic movements - jerky, uncontrolled body movements; short-term memory is lost, the individual's reasoning & decision making capability decreases; the individual may become apathetic & withdrawn, or angry, abusive, hostile |
| What is the treatment and cure for Huntington's disease? | there is no treatment and no cure; the disease is uniformly fatal; a diagnostic test is available for the disease marker on chromosome 4 |
| What is the etiology of cystic fibrosis? | an autosomal recessive disorder, most commonly seen in Caucasians; it causes defective expression of a gene on chromosome 7, which codes for the cystic fibrosis mtransmembrane regulator protein (CFTR protein) which carries the chloride ion out of the cell |
| What is the pathogenesis of cystic fibrosis? | the deficiency of transport proteins causes ion transports in exocrine glands and other tissues to be faulty -> thick, sticky, viscous mucus, especially in the lungs, pancreas and also liver, reproductive organs, and intestines |
| What are the manifestations of cystic fibrosis? | obstruction->chronic respiratory disease->bacterial respiratory infections->pulmonary hypertension (from pulmonary constriction)->heart failure; also, chronic inflammation->structural changes in the lungs & cyst formation; also pancreatic obstruction |
| What is the pathophysiologic triad of cystic fibrosis? | 1) pancreatic enzyme deficiency -> severe malnourishment; 2) overproduction of mucus in the respiratory tract, and 3) abnormally elevated sodium and chloride concentrations in sweat |
| How is cystic fibrosis diagnosed? | by a sweat test; the patient produces a very salty sweat because of abnormal ion transport |
| How is cystic fibrosis treated? | percussion respiratory therapy (to clear mucus & improve lung functions); antibiotics to prevent infections, and enzyme/nutritional supplements to improve digestion & nutrition |
| What are muscular dystrophies? What is the most common? | a group of disorders that cause progressive, symmetric weakness and wasting of skeletal muscle groups; most common is Duchenne muscular dystrophy |
| What is the etiology of Duchenne muscular dystrophy? | it is an X-linked recessive disorder seen only in boys; cause -> gene deletion from the X chromosome |
| What is the pathogenesis of muscular dystrophies? (i.e. the biochemical mechanidsm resulting in the development of a disease) | DMD boys lack dystrophin -> muscle cells are torn apart during muscle contraction -> muscle cells swell and die -> replaced by connective tissue and fat |
| What is the function of dystrophin? Why do DMD boys not have it? | dystrophin is an anchor protein which anchors the muscle cytoskeleton to the surrounding connective tissue; DMD boys lack dystrophin because they are missing the gene on the X chromosome that codes for dystrophin |
| What are the manifestations of Duchenne muscular dystrophy? | clinical signs are observed at about age 3; motor development slow -> difficulty sitting, standing, and walking -> wheelchair; scoliosis, respiratory difficulty, heart failure; smooth muscle involvement -> malabsorption |
| What is the treatment and cure for Duchenne muscular dystrophy? | there is no effective treatment for Duchenne muscular treatment and no cure; death typically occurs before age 20, typically due to cardiopulmonary failure |
| Are females affected? | no; they are only carriers |
| What are hemophilias? | serious bleeding disorders |
| What are the 4 types of hemophilia? | hemophilia A - factor VIII deficiency (antihemophiliac factor) - classic hemophilia; hemophilia B - factor IX deficiency (Christmas disease); Hemophilia C - factor X1 deficiency; von Willebrand disease |
| What is the etiology of hemophilia A? | aka classic hemophilia, it is an X-linked recessive disorder and is the most common form of hemophilia; it is caused by a gene deletion or a point mutation -> results in a total lack of clotting factor VIII |
| What is factor VIII? | a part of the intrinsic mechanism of clotting; when it is deficient, blood is very slow to clot |
| How is classic hemophilia typically inherited? | typically, mom is a phenotypically normal carrier for the disorder; dad is normal as well |
| What is the pathogenesis for classic hemophilia? | boys bleed excessively after circumcision; persistent bleeding after minor injuries; bruise very easily; nosebleeds; bleeding into the joint can damage the joints and cause severe degenerative arthritis |
| What is the treatment/cure for hemophilia? | hemophilia can be treated with regular injections with Factor VIII (now genetically engineered); high risk for contracting AIDS or hepatitis from human plasma; no cure, but aggressive replacement therapy can enable a normal lifespan |
| What is the etiology of galactosemia? | it is an autosomal recessive trait which results in the lack of galactase enzyme, an enzyme needed to convert galactose (a monosaccharide found in lactoes) to glucose |
| What is the pathogenesis of galactosemia? | Without the enzyme, galactose wil accumulate in the blood, liver, brain and other body tissues; osmotic swelling will damage cells in these tissues |
| What are the manifestations for galactosemia? | mental retardation develops; the child show failure to thrive; liver failure occurs and causes jaundice and cirrhosis; cataracts of the lens of the eye |
| What is the cure/treatment for galactosemia? | there is no cure; treatment involves restriction of galactose in the diet |
Created by:
debmurph
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