11-24-2007, 04:00 PM
Here r high yield stuff( DISEASES) which r usually asked in usmle (Biochem).
Best of luck
=====Sickle Cell Anemia (Hb S disease)----- - Results when a glutamate is replaced by valine at position 6 of the b globin chain. Symptoms include anoxia, poor circulation, and crises when variables that lower oxygen affinity (i.e. BPG, ¯pH, etc) are experienced.
=====Thalassemia---- - Results when either the a- or b- chain is defective. One type of thalassemia is caused by a nonsense mutation of codon 17 of the b-globin chain. Other thalassemias may be caused by deletion mutations. Either the a or b chains are involved in such disease and in some cases individuals might be carriers of certain mutations.
=====Tay-Sachs disease---- - Results with a base insertion in exon 11 of the a-chain of the hexoaminidase A gene, the most common found in patients of Ashkenazi Jewish background. Symptons include mental retardation, muscular weakness, blindness, and cherry red macula.
=====Xeroderma Pigmentosum----- - Results when there is a defect in the DNA repair systems specifically a deficiency of endonucleases involved in the removal of pyrimidine dimers (thymine dimers) from DNA. This disorder involves base excision repair and makes patients highly susceptible to skin cancer.
====Hereditary Nonpolyposis Colorectal Cancer ------ Disease caused by mutations in genes for proteins involved in mismatch repair. This cancer does not arise from intestinal polyps.
====Systemic Lupus Erythematosus --- - The body makes antibodies against many of its own snRNPs (small nuclear ribonucleoproteins) which are responsible for the splicing of introns.
===Iron Deficiency Anemia---- - Lack of dietary iron intake causes a decrease in heme synthesis and therefore a decrease in globin synthesis. Heme inhibits the phosphorylation of eIF2. When eIF2 is phosphorylated it is inactive, and protein synthesis is not initiated. Heme thus keeps eIF2 active and maintains globin synthesis so that Hb is made.
====Chronic Myelogenous Leukemia --- - A single line of primitive myeloid cells produces leukemic cells that proliferate abnormally, causing a large increase in the number of white blood cells in the circulation. Typical in CML is the presence of the Philadelphia chromosome which involves an exchange of DNA between chromosomes 9 and 22.
====Scurvy --- - Deficiency in ascorbic acid (vitamin C) which results in poor synthesis of collagen. Vitamin C is a cofactor in the hydroxylation of proline and lysine. Without hydroxylation, the H bonding between helices cannot occur
====Essential Fructosuria--- “ deficiency of fructokinase. Benign asymptomatic condition. Fructose accumulates in the urine.
====Hereditary Fructose Intolerance---- “ absence of aldolase B leads to intracellular trapping of fructose 1-phosphate. Causes severe hypoglycemia, vomiting, jaundice, and hemorrhage. Can cause hepatic failure. Therapy: rapid detection and removal of fructose and sucrose from diet.
====Uridyltransferase deficiency “----- causes galactosemia and galactosuria. Accumulation of galactose 1-phosphate and galactitol in nerve tissue, lens, liver, and kidney causing liver damage, severe mental retardation, and cataracts. Therapy: rapid diagnosis and removal of galactose (lactose) from diet.
====Galactokinase deficiency-- “ causes galactosemia and galactosuria and leads to accumulation of galactitol.
====Pyruvate kinase deficiency---- “ low ATP levels in RBC™s, glycolytic enzymes increased. High 2,3BPG levels which decrease O2 affinity.
====Glucose 6 phosphate dehydrogenase deficiency “--- causes hemolytic anemia. Disease variants include decreased production of enzyme, decreased catalytic activity and lowered stability. X-linked disease affecting over 200 million people. Sulfa drugs and antimalarial drugs induce hemolysis in G-6PD deficient cells. Infection also induces hemolysis.
====Maple Syrup Urine Disease ----“ disease is due to a deficiency in branched-chain a-ketoacid dehydrogenase. Levels of branched-chain amino acids and their a-keto analogues are elevated in plasma and urine. Disease has high mortality rate. Neurologic problems are common.
====Pernicious Anemia “ results from the lack of intrinsic factor which prevents the absorption of vitamin B12 (cobalamin). Patients are usually anemic but in development of the disease show neuropsychiatric symptoms.
====Propionic Acidemia ---“ results from a deficiency in propionyl CoA carboxylase. Elevated levels or propionate (propionic acid) occur in blood. Odd-numbered fatty acids accumulate in liver. Developmental problems occur.
----Methylmalonic Acidemia “ caused by a deficiency in methylmalonyl CoA mutase. Metabolic acidosis and developmental retardation may result.
====Phenylketonuria (PKU)--- “ caused by a deficiency in phenylalanine hydroxylase. Most common inborn error of amino acid metabolism. Small fraction of PKU is due to a deficiency in either dihydrobiopterin (BH2) reductase or dihydrobiopterin synthetase.
====Alkaptonuria---- “ disease due to a deficiency in homogentisate oxidase. Homogentisate accumulates forming polymers that cause urine to darken upon standing. Alkaptonuria is benign.
====Hypertyrosinemia---“ disease due to a deficiency in tyrosine aminotransferase, 4-hydroxyphenylpyruvate dioxygenase, or fumarylacetoacetate hydrolase.
====McArdle™s Disease--- “ results from a deficiency of glycogen phosphorylase in skeletal muscle. Moderate increase in muscle glycogen. Normal fasting glucose levels in blood. Vigorous exercise increases muscle ADP, induces cramps. Low lactate accumulation during exercise relative to unaffected individuals, consistent with decreased glycogen utilization in muscle.
====Cori™s Disease--- “ results from a deficiency in debranching enzyme (glucosyl transferase) in muscle and liver. Abnormal glycogen structure (short outer branches) increased content. Hepatomegaly and cardiomegaly present. Hypoglycemia due to insufficient glycogen breakdown; growth retardation.
=====VonGierke™s Disease--- “ results from a deficiency in glucose 6 phosphatase. Severe fasting hypoglycemia with elevated lactate and pyruvate. Hepatomegaly, excess glycogen with normal structure.
====Pompe™s Disease--- “ results from a deficiency in lysosomal a-glucosidase in liver, heart, and muscle. Normal blood glucose levels. Increased liver glycogen, normal structure, accumulation in cytosol granules. Severe cardiomegaly and early death occur.
====Phorphyrias ---“ Result from a deficiency in enzymes of heme biosynthesis pathway.
====Gout---- “ Disease caused by excessive uric acid levels in blood. Can result from overproduction of purines or from decreased ability to excrete uric acid. Disease is treated with allopurinol which inhibits xanthine oxidase.
====Lesch-Nyhan syndrome--- “Caused by the defective enzyme HGPRT (hypoxanthine-guanine phosphoribosyltransferase) that is involved in salvage of purines. Excessive amounts of uric acid are also produced.
====Tay-Sachs disease--- “ Deficiency in hexosaminidase A. Leads to accumulation of gangliosides.
===Gaucher™s disease ---“ Deficiency in b-glucosidase. Leads to accumulation of glucocerebrosides.
====Niemann Pick disease---- “ Deficiency in sphingomyelinase. Leads to accumulation of sphingomyelin.
=====Type I Hyperlipidemia---- “ Deficiency in either lipoprotein lipase or Apo C-II. High serum TG due to accumulation of chylomicrons and VLDLs.
====Type II Hyperlipidemia ----“ Deficiency in LDL receptor. High serum cholesterol and CE due to LDL accumulation. No down regulation of cholesterol biosynthesis.
----Type III Hyperlipoproteinemia--- “ Defects in liver receptor and Apo B48. Failure to clear chylomicrons.
=====Coronary Artery Disease----- “ Oxidatively damaged LDLs are recognized by macrophages. High blood glucose (as in diabetes) activates macrophage uptake. Uptake of LDL cholesterol does not down regulate synthesis of scavenger receptors. Excess cholesterol leads to foam cell formation and deposit in artery.
=====I cell disease---- “ Characterized by lack of
phosphotransferase so mannose is not phosphorylated and can™t be targeted to lysosomes. Lysosomal enzymes are exported from the cell and are found in plasma. Lysosomes become deficient in most degradative enzymes.
Best of luck
=====Sickle Cell Anemia (Hb S disease)----- - Results when a glutamate is replaced by valine at position 6 of the b globin chain. Symptoms include anoxia, poor circulation, and crises when variables that lower oxygen affinity (i.e. BPG, ¯pH, etc) are experienced.
=====Thalassemia---- - Results when either the a- or b- chain is defective. One type of thalassemia is caused by a nonsense mutation of codon 17 of the b-globin chain. Other thalassemias may be caused by deletion mutations. Either the a or b chains are involved in such disease and in some cases individuals might be carriers of certain mutations.
=====Tay-Sachs disease---- - Results with a base insertion in exon 11 of the a-chain of the hexoaminidase A gene, the most common found in patients of Ashkenazi Jewish background. Symptons include mental retardation, muscular weakness, blindness, and cherry red macula.
=====Xeroderma Pigmentosum----- - Results when there is a defect in the DNA repair systems specifically a deficiency of endonucleases involved in the removal of pyrimidine dimers (thymine dimers) from DNA. This disorder involves base excision repair and makes patients highly susceptible to skin cancer.
====Hereditary Nonpolyposis Colorectal Cancer ------ Disease caused by mutations in genes for proteins involved in mismatch repair. This cancer does not arise from intestinal polyps.
====Systemic Lupus Erythematosus --- - The body makes antibodies against many of its own snRNPs (small nuclear ribonucleoproteins) which are responsible for the splicing of introns.
===Iron Deficiency Anemia---- - Lack of dietary iron intake causes a decrease in heme synthesis and therefore a decrease in globin synthesis. Heme inhibits the phosphorylation of eIF2. When eIF2 is phosphorylated it is inactive, and protein synthesis is not initiated. Heme thus keeps eIF2 active and maintains globin synthesis so that Hb is made.
====Chronic Myelogenous Leukemia --- - A single line of primitive myeloid cells produces leukemic cells that proliferate abnormally, causing a large increase in the number of white blood cells in the circulation. Typical in CML is the presence of the Philadelphia chromosome which involves an exchange of DNA between chromosomes 9 and 22.
====Scurvy --- - Deficiency in ascorbic acid (vitamin C) which results in poor synthesis of collagen. Vitamin C is a cofactor in the hydroxylation of proline and lysine. Without hydroxylation, the H bonding between helices cannot occur
====Essential Fructosuria--- “ deficiency of fructokinase. Benign asymptomatic condition. Fructose accumulates in the urine.
====Hereditary Fructose Intolerance---- “ absence of aldolase B leads to intracellular trapping of fructose 1-phosphate. Causes severe hypoglycemia, vomiting, jaundice, and hemorrhage. Can cause hepatic failure. Therapy: rapid detection and removal of fructose and sucrose from diet.
====Uridyltransferase deficiency “----- causes galactosemia and galactosuria. Accumulation of galactose 1-phosphate and galactitol in nerve tissue, lens, liver, and kidney causing liver damage, severe mental retardation, and cataracts. Therapy: rapid diagnosis and removal of galactose (lactose) from diet.
====Galactokinase deficiency-- “ causes galactosemia and galactosuria and leads to accumulation of galactitol.
====Pyruvate kinase deficiency---- “ low ATP levels in RBC™s, glycolytic enzymes increased. High 2,3BPG levels which decrease O2 affinity.
====Glucose 6 phosphate dehydrogenase deficiency “--- causes hemolytic anemia. Disease variants include decreased production of enzyme, decreased catalytic activity and lowered stability. X-linked disease affecting over 200 million people. Sulfa drugs and antimalarial drugs induce hemolysis in G-6PD deficient cells. Infection also induces hemolysis.
====Maple Syrup Urine Disease ----“ disease is due to a deficiency in branched-chain a-ketoacid dehydrogenase. Levels of branched-chain amino acids and their a-keto analogues are elevated in plasma and urine. Disease has high mortality rate. Neurologic problems are common.
====Pernicious Anemia “ results from the lack of intrinsic factor which prevents the absorption of vitamin B12 (cobalamin). Patients are usually anemic but in development of the disease show neuropsychiatric symptoms.
====Propionic Acidemia ---“ results from a deficiency in propionyl CoA carboxylase. Elevated levels or propionate (propionic acid) occur in blood. Odd-numbered fatty acids accumulate in liver. Developmental problems occur.
----Methylmalonic Acidemia “ caused by a deficiency in methylmalonyl CoA mutase. Metabolic acidosis and developmental retardation may result.
====Phenylketonuria (PKU)--- “ caused by a deficiency in phenylalanine hydroxylase. Most common inborn error of amino acid metabolism. Small fraction of PKU is due to a deficiency in either dihydrobiopterin (BH2) reductase or dihydrobiopterin synthetase.
====Alkaptonuria---- “ disease due to a deficiency in homogentisate oxidase. Homogentisate accumulates forming polymers that cause urine to darken upon standing. Alkaptonuria is benign.
====Hypertyrosinemia---“ disease due to a deficiency in tyrosine aminotransferase, 4-hydroxyphenylpyruvate dioxygenase, or fumarylacetoacetate hydrolase.
====McArdle™s Disease--- “ results from a deficiency of glycogen phosphorylase in skeletal muscle. Moderate increase in muscle glycogen. Normal fasting glucose levels in blood. Vigorous exercise increases muscle ADP, induces cramps. Low lactate accumulation during exercise relative to unaffected individuals, consistent with decreased glycogen utilization in muscle.
====Cori™s Disease--- “ results from a deficiency in debranching enzyme (glucosyl transferase) in muscle and liver. Abnormal glycogen structure (short outer branches) increased content. Hepatomegaly and cardiomegaly present. Hypoglycemia due to insufficient glycogen breakdown; growth retardation.
=====VonGierke™s Disease--- “ results from a deficiency in glucose 6 phosphatase. Severe fasting hypoglycemia with elevated lactate and pyruvate. Hepatomegaly, excess glycogen with normal structure.
====Pompe™s Disease--- “ results from a deficiency in lysosomal a-glucosidase in liver, heart, and muscle. Normal blood glucose levels. Increased liver glycogen, normal structure, accumulation in cytosol granules. Severe cardiomegaly and early death occur.
====Phorphyrias ---“ Result from a deficiency in enzymes of heme biosynthesis pathway.
====Gout---- “ Disease caused by excessive uric acid levels in blood. Can result from overproduction of purines or from decreased ability to excrete uric acid. Disease is treated with allopurinol which inhibits xanthine oxidase.
====Lesch-Nyhan syndrome--- “Caused by the defective enzyme HGPRT (hypoxanthine-guanine phosphoribosyltransferase) that is involved in salvage of purines. Excessive amounts of uric acid are also produced.
====Tay-Sachs disease--- “ Deficiency in hexosaminidase A. Leads to accumulation of gangliosides.
===Gaucher™s disease ---“ Deficiency in b-glucosidase. Leads to accumulation of glucocerebrosides.
====Niemann Pick disease---- “ Deficiency in sphingomyelinase. Leads to accumulation of sphingomyelin.
=====Type I Hyperlipidemia---- “ Deficiency in either lipoprotein lipase or Apo C-II. High serum TG due to accumulation of chylomicrons and VLDLs.
====Type II Hyperlipidemia ----“ Deficiency in LDL receptor. High serum cholesterol and CE due to LDL accumulation. No down regulation of cholesterol biosynthesis.
----Type III Hyperlipoproteinemia--- “ Defects in liver receptor and Apo B48. Failure to clear chylomicrons.
=====Coronary Artery Disease----- “ Oxidatively damaged LDLs are recognized by macrophages. High blood glucose (as in diabetes) activates macrophage uptake. Uptake of LDL cholesterol does not down regulate synthesis of scavenger receptors. Excess cholesterol leads to foam cell formation and deposit in artery.
=====I cell disease---- “ Characterized by lack of
phosphotransferase so mannose is not phosphorylated and can™t be targeted to lysosomes. Lysosomal enzymes are exported from the cell and are found in plasma. Lysosomes become deficient in most degradative enzymes.