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USMLE Metabolic Disorders

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pipojiya's version from 2017-06-21 13:47

Metabolic Disorders

Question Answer Column 3 Column 4 Column 5 Column 6 Column 7
NameEnzymeExcess metabolitesDeficient metabolitesGeneticsSymptomsTreatment
Most common human enzyme deficiencyG6PD defHb precipitatesNADPHX recessiveHeinz Bodies (Hb preciptations removed by phagocytes creating bite cells)
Essential fructosuriaFructokinase defFructoseemia/uriaNoneAutosomal recessiveBenign/fructoseuria/emiaNone
Fructose intoleranceAldolase B defFructose 1 phosphate accphosphate deficientAutosomal recessiveHypoglycemia/jaundice/cirrhosis/vomitingDecrease fructose/sucrose
GalactosuriaGalactokinase deficiencyGalactose/Galactitol accumulatesNoneAutosomal recessiveBenign/galactosuria/emia/infantile cataract/failure to tract objects/social smileNone
Classic galactosemiaUridyltransferase def (glucose/galactose)Galactitol/toxic metabolites accNoneAutosomal recessiveFailure to thrive/jaundice/hepatomegaly/infantile cataracts/mental retardationDecrease galactose/lactose
Lactose intoleranceLactase defLactose accNoneAge dependent and/or hereditary (africans/asians)Bloating/cramps/osmotic diarrheaAvoid dairy/lactase pills
HyperammonemiaUrea cycle enzyme deficiencies/liver diseaseAmmonia/nitrogenous accAlpha Ketoglutarate depletion (from NH4+)/stopping TCAAcquired liver disease or hereditary urea cycle enzyme deficiencies (most autosomal recessive)Ammonia intoxication (tremor/asterixis/slurring/somnolence/vomiting/cerebral edema/blurred vision)Limit protein/benzoate or phenylbutryrate bind amino acids for excretion/lactulose acidifies GI to trap NH4 for excretion
Most common urea cycle disorderOrnithine transcarbamoylase deficiencyAmmonia/nitrogenous/orotic acid accAlpha Ketoglutarate/BUN deficientX recessiveAmmonia intoxication (tremor/asterixis/slurring/somnolence/vomiting/cerebral edema/blurred vision)None
PhenylketonuriaPhenylalanine hydroxylase defPhenylalanine/phenylketones in urine accNoneAutosomal recessiveMental retardation/growth retardation/seizures/fair skin/eczema/musty body odor (aromatic amino acid)Decrease phenylalanine (aspartame in NutraSweet)/increase tyrosine
Alkaptonuria/ochronosisHomogentisic acid oxidase def
(helps convert tyrosine to fumarate)
Homogentisic acid accNoneAutosomal recessiveBenign/dark connective tissue/brown sclera/urine black on exposure to air/HGA toxic to cartilage causing arthralgiasNone
AlbinismTyrosinase def
(contains copper)/tyrosine transporters
NoneMelaning/Tyrosine deficinecy
(when transporters defective)
Variable (ocular is X recessive)Risk of skin cancerNone
Homocystinuria 1Cystathionine synthase deficiency (normally leads to cysteine)Homocysteine accCysteine deficiencyAutosomal recessiveMental retardation/osteoporosis/tall/kyphosis/lens subluxation/atherosclerosisCysteine essential/Decrease methionine/increase cysteine/B12/folate
Homocystinuria 2Cystathionine synthase affinity for pyridoxal phosphateHomocysteine accCysteine deficinecyAutosomal recessiveMental retardation/osteoporosis/tall/kyphosis/lens subluxation/atherosclerosisCysteine essential/Increase B6
Homocystinuria 3Homocysteine methyltransferase deficiency
(normally leads to methionine)
Homocysteine accCysteine deficiencyAutosomal recessiveMental retardation/osteoporosis/tall/kyphosis/lens subluxation/atherosclerosisCysteine essential
CystinuriaAmino acid transporter def
(Cyst/Orni/Lys/Arg) in PCT
Cysteine accNoneAutosomal recessiveCystine (2 cysteine) hexagonal crystals/staghorn calculiHydration/urinary alkalinization
Maple Syrup Urine DiseaseAlpha ketoacid dehydrogenase (B1) defBranched chain amin acids (Ile/Leu/Val)NoneAutosomal recessiveCNS defects/mental retardation/death/maple syrup urineNone
HartnupAA transporter def
on renal/intestinal epithelia (tryptophan def)
NoneTryptophan deficiency
so Niacin eficiency
Autosomal recessivePellagra (Niacine/B3 deficiency/dermatitis/dementia/diarrhea)None
I Von GierkeG6P def
Glucose 6 phosphatase
Hepatic glycogen/lactate acc in bloodGlucose deficiencyAutosomal recessiveSevere fasting hypoglycemia/hepatomegalyNone
II PompeLysosomal alpha 1/4 glucosidase def
/acid maltase
Lysosomal glycogen accNoneAutosomal recessiveCardiomegaly (pompe = pump)/systemic/deathNone
III Corialpha 1/6 glucosidase def
Debranching enzyme
Branched glycogen accGlucose deficiencyAutosomal recessiveHypoglycemia/hepatomegaly
(ABCD = Ardle branching Cori Debranching)
None
V McArdleSkeletal muscle glycogen phosphorylase defMuscle glycogen accNoneAutosomal recessivePainful muscle cramps/myoglobinuria with strenuous exerciseNone
FabryAlpha galactosidase A defCeramide trihexoside accNoneAutosomal recessivePeripheral neuropathy of hands/feet/angiokeratomas/CV/renal diseaseNone
GaucherGlucocerebrosidase defGlucocerebroside accNoneAutosomal recessiveHepatosplenomegaly/aseptic femur necrosis/bone crises/Gaucher cells (macrophages like crumpled paper)None
Niemann PickSphingomyelinase defSphingomyelin accNoneAutosomal recessiveProgressive neurodegeneration/hepatosplenomegaly ( sphingomyelin accumulated in liver and brain)/cherry red spot macula/foam cellsNone
Tay SachsHexosaminidase A defGM2 ganglioside accNoneAutosomal recessiveProgressive neurodegeneration/developmental delay/cherry red spot on macula/lysosomes with onion skin/ NO hepatosplenomegaly
absent startle reflex with acoustic stimuli
None
KrabbesGalactocerebrosidase defGalactocerebroside accNoneAutosomal recessivePeripheral neuropathy/developmental delay/optic atrophy/globoid cellsNone
Metachromic LeukodystrophyArylsulfatase A defCerebroside sulfate accNoneAutosomal recessiveCentral/peripheral demyelination w/ataxia/dementiaNone
HurlersAlpha L iduronidase defHeparan sulfate/dermatan sulfate accNoneAutosomal recessiveDevelopmental delay/gargoylism/airway obstruction/corneal clouding/hepatosplenomegalyNone
HuntersIduronate sulfatase defHeparan sulfate/dermatan sulfate accNoneX recessiveMild developmental delay/gargoylism/airway obstruction/hepatosplenomegaly/aggressive behavior, NO CORNEAL CLOUDINGNone
Carnitine deficiencyInability to transfer LCFAs into mitochondriaToxic LCFA accumulationHypoketotic hypoglycemiaN/AWeakness/hypotonia/hypoketotic hypoglycemiaNone
I hyperchylomicronemiaLipoprotein lipase deficiencyChylomicrons/TG/Cholesterol accNoneAutosomal recessivePancreatitis/hepatosplenomegaly/eruptive/pruritic xanthomas/NO increased atherosclerosisNone
IIa familial hypercholesterolemiaAbsent/decreased LDL receptorLDL/cholesterol accNoneAutosomal dominantAccelerated atherosclerosis/tendon xanthomas/corneal arcusNone
IV hypertriglyceridemiaVLDL overproductionVLDL/TG accNoneAutosomal dominantPancreatitisNone
Abetalipoproteinemiatriglyceride transfer protein/cannot export lipid to chylomicronsIntestinal lipids/ fat accumulates in enterocytesB48/B100Autosomal recessiveFailure to thrive - d/t malabsorbtion of fat soluble vit ADEK/steatorrhea/acanthocytosis/ataxia/night blindnessNone
Pyruvate DeH2ase deficiencyPyruvate dehydrogenase defPyruvate/lactate accNoneX linkedLactic acidosis/Neurologic defects/usually in infancyIncrease ketogenic nutrients (fat/leucine/lysine)
KwashiorkorDietary protein defNoneProtein malnutritionDietaryMEAL (Malnutrition/Edema/Anemia/Liver Fatty)None
MarasmusEnergy MalnutritionNoneEnergy malnutritionDietaryMuscle wastingNone
SCIDAdenosine deaminase defATP/dATP accDNA synthesis deficiency - dec lythocytes - dec in B cell - dec in all gamaglobulinsAutosomal recessiveLymphocytes down
lack of gammaglobulins
recurrent infections
None
Lesch NyhanHGPRT def
He;s Got Purine Recovery Trouble
Uric acid accPurines deficiencyX recessiveRetardation/self mutilation/aggression- bites lips and hands/hyperuricemia/gout/choreoathetosisNone
Orotic aciduriauridine monophosphate synthase def
(orotic acid to UMP)
Orotic acid in urine/NO hyperammonemiaUMP deficiencyAutosomal recessiveMegaloblastic anemia/failure to thrive/orotic acid in urineOral uridine
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