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Eric Niederhoffer, Ph.D. SIU-SOM Year Two Review.

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Presentation on theme: "Eric Niederhoffer, Ph.D. SIU-SOM Year Two Review."— Presentation transcript:

1 Eric Niederhoffer, Ph.D. SIU-SOM Year Two Review

2 Outline Pyrimidine and purine synthesis including salvage and degradation Glycogen storage disorders Lysosomal storage disorders Heme synthesis and degradation including oxygen binding/unloading of heme Integration of metabolism including lipid synthesis/degradation, glycolysis/gluconeogenesis, TCA cycle and glycogenolysis/glycogen synthesis

3 Pyrimidine and Purine Synthesis HCO 3 - + Gln CP CPSII Asp Oro R5P PRPP RPK UTP TSN 5,N 10 -mTHF dTMP DNA RNA dGTPdATP RR GDPADP IMP Gln Gly CO 2 Asp N 10 fTHF UMP UMPS CDP dCDP dUMP

4 Pyrimidine and Purine Salvage UT PRPP UMPTMP RR UTPT G PRPP HGPT A APT X XO adenosine inosine ADA HX PNP urate XO UTP CDP dCDP dUMP TSN 5,N 10 -mTHF dTMP RNADNA IMP GDPADP dGTPdATP RR

5 Pathway Disorders Rare autosomal recessive disorders UMP synthase – deficiency in either orotate phosphoribosyltransferase or OMP decarboxylase leads to hereditary orotic aciduria, megaloblastic anemia appearing weeks to months after birth that does not respond to cobalamin, folic acid, or iron, orotic crystalluria and nephropathy, cardiac malformations, strabismus, and recurrent infection. Urine orotic acid overexcretion. Enzyme assay of RBC. Treatment with oral uridine. Adenosine deaminase – ( Severe combined immunodeficiency disorder) variety of clinical phenotypes, history of infections, diarrhea, dermatitis, and failure to thrive, ribs and vertebrae abnormalities (defects in cartilaginous structures). Lymphopenia, B and T cell production affected. Enzyme assay of RBC/WBC. Treatment by bone marrow/stem cell transplantation or enzyme replacement. Purine nucleotide phosphorylase – (Immunodeficiency) lymphopenia, thymic deficiency, recurrent infections, and hypouricemia, developmental delay, ataxia, or spasticity. T cell production affected. Enzyme assay of RBC, lymphocytes, fibroblasts. Treatment by bone marrow/stem cell transplantation. Adenine phosphoribosyl transferase – frequent infections, renal colic, renal failure. Elevated urine levels of 2,8- dihydroxyadenine, 8-hyroxyadenine, and adenine; serum uric acid normal. Enzyme assay. Treated with dietary purine restriction, high fluid intake, and avoidance of urine alkalinization, Allopurinol to prevent oxidation of adenine.

6 Pathway Disorders X-linked recessive disorder Hypoxanthine-guanine phosphoribosyl transferase – ( Lesch-Nyhan syndrome) usually presents at 3 to 12 months with orange sandy urine precipitate, dystonia, intellectual disability, self-mutilation (lips, tongue, fingers), and gout. Elevated serum and urine uric acid levels. Enzyme assay on RBC, lymphocytes, fibroblasts. Molecular genetics of gene. Treated supportively with low-purine diet, allopurinol, and plenty of hydration.

7 Glycogen Storage Disorders hPP GSDVI hG6Pase GSDI mPP GSDV debranching enzyme GSDIII PFK-1 GSDVII transglycosylase branching enzyme GSDIV GS GSD0 Glycogen G1P G6PGlc UDP-Glc F6P F16BP acid maltase GSDII ls

8 Pathway Disorders Rare autosomal recessive disorders Glycogen synthase –.(GSD type 0) fasting hypoglycemia, ketosis, especially before feeding. Periodic acid-Schiff stain shows decreased hepatic glycogen stores, muscle is normal. Treatment is appropriate diet to avoid hypoglycemia. Glucose-6-phosphatase – (GSD type Ia, Von Gierke) history hypoglycemic seizures, hypotonia, hepatomegaly, xanthomas, manifestations of gout, hypertension, renal failure, and short stature. Fasting glucose, ischemic forearm test (negative), Enzyme assay. Treatment by high-protein diet, uncooked corn starch. Lysosomal acid maltase – (GSD type II, Pompe, -1,4- glucosidase); infantile - feeding and breathing difficulties, hypotonia, cardiomegaly; adult – limb-girdle weakness, respiratory muscle involvement. Hyperlipidemia, fasting ketonemia. Ischemic forearm test normal. Enzyme assay of fibroblasts. Periodic acid-Schiff stain is positive for lysosomal glycogen inclusions. Treatment by enzyme relacement, high protein diet. Debranching enzyme – (GSD type III, Forbes-Cori, amylo-1,6- glucosidase), infantile seizures, hepatomegaly, growth retardation, progressive muscle weakness. Ischemic forearm test positive. Enzyme assay of fibroblasts. Periodic acid-Schiff stain is positive for basophilic glycogen deposits in all tissues. Treatment is supportive by corn starch, liver transplantation.

9 Pathway Disorders Rare autosomal recessive disorders Branching enzyme – (GSD type IV, Andersen, transglucosidase) history not specific, hepatic failure, cirrhosis, hepatosplenomegaly, failure to thrive. Prenatal PCR and DNA analysis. Enzyme assay. Diffuse amylopectin-like deposits in the heart, liver, muscle, spinal cord, and peripheral nerves. Treatment is supportive with liver transplantation and diet. Myophosphorylase – (GSD type V, McArdle) cramps, fatigue, and pain after exercise (depends on severity of deficiency), unique "second-wind" phenomenon. Ischemic forearm test positive. Enzyme assay. Periodic acid-Schiff stain gives subsarcolemmal blebs. Treatment by avoiding intense exercise, provide high protein diet. Hepatic phosphorylase – (GSD type VI, Hers) most common among Mennonite religious group, also X-linked form, history of bulging abdomen, growth retardation, and slight delay in motor milestones, hepatomegaly. Enzyme assay on liver biopsy, RBC, WBC; molecular genetics of gene. Glycogen-distended hepatocytes, muscle normal. Treatment with dietary management as appropriate for clinical presentation. Phosphofructokinase-1 – (GSD type VII, Tarui, M form, classic) history of exertional fatigue, nausea and vomiting, muscle cramps, hyperuricemia, myoglobinuria following high-intensity exercise. Ischemic forearm test positive. Enzyme assay on muscle biopsy. Periodic acid-Schiff diastase-negative stain gives subsarcolemmal blebs. Treatment to avoid high carbohydrate diet especially before exercise.

10 Lysosomal Storage Disorders Lipid metabolism Landing, Sandhoff, Tay-Sachs, Krabbe, Gaucher, Niemann Pick (A,B), Wolman, metachromatic leukodystrophy, Fabry Glycoprotein metabolism Schindler Mucopolysaccharide metabolism Hurler/Scheie, Hunter, Sanfilippo (A,B,C,D), Morquio (A,B), Maroteaux–Lamy, Sly Other lysosomal enzymes Pompe, Niemann-Pick (C)

11 Oligosaccharidoses NANAGalGlcNAc Man NANAGalGlcNAc NANAGalGlcNAc NANAGalGlcNAc Man GlcNAc Fuc Asn 12 3 4 5 6 7 8 3 4 4 4 5 5 5 6 6 6 Typical Asn-GlcNAc OS structure Aspartylglycosylaminuria 4-L-Aspartylglycosylamine amidohydrolase -Mannosidosis -Mannosidase GM 2 gangliosidosis variant O (Sandhoff-Jatzkewitz disease) -N-Acetylhexosaminidases A&B GM 1 gangliosidosis -Galactosidase Mucolipidosis I (Sialidosis) Sialidase -Mannosidosis -Mannosidase Fucosidosis -Fucosidase

12 Glycosaminoglycoses (mucopolysaccharidoses) HS IdUA GlcNGlcUA GlcNAc OSO 3 H DSIdUA GalNAcGlcUAGalNAc OSO 3 H 1 2 3 5 5 6 7,9 8 9 1 24 KS Gal GlcNAc GalGlcNAc OSO 3 H 10 11 8 4 Aldurazyme® (laronidase) Maroteaux-Lamy N-acetylgalactosamine sulfatase Sandhoff/Tay-Sachs -hexosaminidase A,B,S Hunters iduronate sulfatase Hurler-Scheie -L-iduronidase Mucolipodosis VII -glucuronidase Sanfilippos A heparan N-sulfatase Sanfilippos C Acetyl-CoA: -glucosaminide acetyltransferase Sanfilippos D N-acetylglucosamine-6-sulfatase Sanfilippos B N-acetylglucosaminidase Morquios A N-acetylgalactose-6-sulfatase Morquios B galactosidase

13 Gangliosidoses CerPC S + FA Cer neuraminidase (sialidase) G D1 Cer Gal Glu NANA GalNAcGal G M1 CerGalGlu NANA GalNAcGal G M2 CerGalGlu NANA GalNAc G M3 CerGalGlu NANA CerGalGlu CerGlu CerGal Glu CerGal CerGalSO 3 H CerGal GluGalNAc Generalized gangliosidosis -galactosidase Tay-Sachs disease -hexosaminidase A GM2 activator Sialidosis neuraminidase (sialidase) SAP-B -galactosidase SAP-B, SAP-C Gauchers disease -glucosylceramidase SAP-C Sandhoffs disease -hexosaminidase A&B Fabrys disease -galactosidase A SAP-B Niemann-Pick disease sphingomyelinase Metachromatic leukodystrophy arylsulfatase A SAP-B Krabbes disease -galactosylceramidase SAP-A, SAP-C Cerezyme

14 General Physical Features Coarse facial features (sometimes with macroglossia) Corneal clouding or related ocular abnormalities Angiokeratoma Umbilical/inguinal hernias Short stature Developmental delays Joint or skeletal deformities Organomegaly (especially liver and spleen) Muscle weakness or lack of control (ataxia, seizures, etc.) Neurologic failure/decline or loss of gained development


16 Pathway Disorders PBG synthase – (5-aminolevulinic acid dehydratase) extremely rare autosomal recessive (hepatic porphyria) neurological findings, abdominal tenderness, neuropathy, not associated with cutaneous photosensitivity. Elevated urine ALA, coproporphyrin III and protoporphyrin IX, normal PBG, elevated RBC zinc protoporphyrin but decreased (80%) PBG synthase. DNA analysis. Treatment by avoiding precipitating factors, drugs that induce P450 induction, provide hematin, high carbohydrate diet (glucose inhibits 5-AS). PBG deaminase – (Acute intermittent porphyria) autosomal dominant, abdomen pain, psychiatric symptoms (hysteria), motor neuropathies (more commonly lower limbs), and constipation but no skin rash. Increased urinary porphobilinogen secretion, molecular genetic analysis. Treatment during attacks with high carbohydrate (glucose) diet and hematin, otherwise, balanced diet. Uroporphyrinogen III synthase – (Congenital erythropoetic porphyria, Gunther disease) rare autosomal recessive, photosensitivity, nail abnormalities, brown or pink teeth. Elevated urine and RBC levels of uroporphyrin I, hemolytic anemia. Enzyme assay, molecular genetic analysis, red porphyrin fluorescence in intact RBC and erythroid precursor cells. Treated with absolute avoidance of sun exposure, supportive/cosmetic care. Uroporphyrinogen III decarboxylase – (Porphia cutana tarda) 80% acquired/20% familial/autosomal dominant, acquired by ethanol abuse, estrogen therapies, hemochromatosis genes, hepatitis and human immunodeficiency viral infections, environmental toxins, photosensitivity, tea/wine colored urine. Carboxylated porphyrins in serum and urine. Enzyme assay of RBC, molecular genetic analysis. Treatment with avoidance of sunlight/environmental exposure.

17 Pathway Disorders Coproporphyrinogen oxidase – (Hereditary coproporphyria) autosomal dominant, abdominal pain, neuropathies (motor, lower limbs), constipation, and skin changes (photosensitivity). Excess secretion and levels of coproporphyrins in stool and urine. Treatment with high carbohydrate (glucose) diet and hematin. Protoporphyrinogen oxidase – (Variegate porphyria) autosomal dominant, photosensitivity, abdominal discomfort. Urinary aminolevulinic acid and porphobilinogen levels are greatly elevated during attacks, molecular genetic analysis. Treatment with avoidance of inducing drugs, providing high carbohydrate diet, hematin. Ferrochelatase – (Erythropoetic protoporphyria) autosomal dominant (X-linked, autosomal recessive), photosensitivity, heptabiliary disease, jaundice. Elevated protoporphyrin concentration in red blood cells, plasma, bile, and feces. Treatment with avoidance of sun exposure, maintain balanced diet.

18 Heme Degradation BVR BR indirect unconjugated pre-hepatic HO BVHeme ER hepatocyte direct conjugated post-hepatic albumin albumin-BR ligandin albumin ligandin-BR BR diglucuronide UDP-GT res

19 Pathway Disorders Autosomal recessive disorders UDP-glucuronyl transferase – mild deficiency (Gilbert syndrome) most common inherited cause of unconjugated hyperbilirubinemia, intermittent jaundice without hemolysis or liver disease, precipitated by dehydration, fasting, menstrual periods, intercurrent illness, trauma, over exertion, nonspecific symptoms such as abdominal cramps, fatigue, and malaise, mild jaundice. Unconjugated hyperbilirubinemia (by definition [bilirubin] < 6 mg/dL, commonly < 3 mg/dL), normal complete blood count, reticulocyte count, and blood smear, normal liver function panel. Treatment is reassurance and avoiding precipitating factors. UDP-glucuronyl transferase – severe deficiency (Crigler- Najjar syndrome) rare, types 1 and 2 (Arias syndrome). Type 1 almost complete deficiency associated with neonatal unconjugated hyperbilirubinemia (17-50 mg/dL) and kernicterus, hypotonia, deafness, oculomotor palsy, lethargy. Type 2 deficiency unconjugated bilirubin (6-20 mg/dL), persistent jaundice at birth or after. Elevated unconjugated bilirubin with normal liver function panel. Phenobarbital treatment distiguished type 1 (no effect) from type 2 (lowers serum bilirubin 25%). Treatment of bilirubin encephalopathy with plasma exchange transfusion and long-term phototherapy.

20 O 2 Binding/Unloading

21 Hemoglobin Structure Changes

22 Factors Affecting Binding of O 2 Depends on pH ([H + ]), CO 2, BPG (DPG), Temp

23 Integration of Metabolism SSB metabolism in brain, nervous tissue and muscle alcohol processing and effect on metabolic pathways vitamins in neuromuscular metabolism ERG regulation of metabolism and diabetes

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