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STEP 1 > Biochem > Flashcards

Biochem Flashcards

1
Q

I Cell Disease

A
  • Inherited lysosomal storage disease
  • Defect in N-acetylglucosaminyl-1-phosphotransferase, failure of Golgi to phosphorylate mannose residues (↓ mannose-6-phosphate)
  • Proteins secreted extracellularly instead of delivered to lysosomes
  • Coarse facial features, clouded corneas, restricted joint movement, high plasma levels of lysosomal enzymes
  • Often fatal in childhood
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2
Q

Zellweger syndrome

A
  • Peroxisomal disorder (deficit in synthesis of plasmalogens)
  • Hypotonia, Seizures, Hepatomegaly, early death
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3
Q

Refsum Disease

A
  • Peroxisomal disorder
  • Scaly skin, ataxia, cataracts/night blindness, shortening of 4th toe, epiphyseal dysplasia
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4
Q

Prader-Willi Syndrome

A
  • Maternal imprinting, Paternal gene is deleted/mutated
  • Hyperphagia, obesity, intellectual disability, hypogonadism, hypotonia
  • 25% due to maternal uniparental disomy
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5
Q

Angelman syndrome

A
  • Paternal imprinting (paternal gene normally silent), maternal gene is deleted/mutated
  • Inappropriate laughter (“happy puppet”), seizures, ataxia, and severe intellectual disability
  • 5% due to paternal uniparental disomy
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6
Q

Fragile X Syndrome

A
  • X-linked Dominant, trinucleotide repeat in FMR1 gene (CGG), hypermethylation & decreased expression
  • Most common cause of inherited intellectual disability and autism
  • Macroorchidism, long face, large jaw, large everted ears, autism, mitral valve prolapse
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7
Q

Edwards Syndrome

A
  • Trisomy 18
  • Prominent occiput, rocker-bottom feet, Intellectual disability, Nondisjunction, Clenched fists, low-set Ears, micrognathia, congenital heart disease
  • Death by age 1
  • ↓β-hCG, ↓α-fetoprotein, ↓estriol, ↓ or normal inhibin A
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8
Q

Patau Syndrome

A
  • Trisomy 13
  • Severe intellectual disability, Rocker-bottom feet, micropthalmia, microcephaly, cleft liP/Palate, holoProsencephaly, Polydactyly, cutis aPlasia, congenital heart disease
  • Death by age 1
  • ↓βhCG, ↓PAPP-A
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9
Q

Cri-du-Chat Syndrome

A
  • Congenital deletion on short arm of chromosome 5
  • Microcephaly, moderate to severe intellectual disability, high-pitched crying/meowing, epicanthal folds, cardiac abnormalities (VSD)
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10
Q

Williams Syndrome

A
  • Congenital microdeletion of long arm of chromosome 7 (deleted region includes elastin gene)
  • Elfin facies, intellectual disability, hypercalcemia (increased Vit D sensitivity), well-developed verbal skills, extreme friendliness with strangers, cardiovascular problems
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11
Q

Thiamine is a cofactor for what enz?

A
  • Pyruvate Dehydrogenase (links glycolysis to TCA)
  • α-ketoglutarate dehydrogenase (TCA)
  • Transketolase (HMP shunt)
  • Branched-chain ketoacid dehydrogenase
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12
Q

B2 is cofactor for what enz?

A
  • Succinate dehydrogenase (FAD and FMN)
  • Complex II in electron transport chain
  • Deficiency: Cheilosis, Corneal vascularization
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13
Q

B7 is cofactor for what enz?

A

Cofactor for carboxylation enzymes

  • Pyruvate carboxylase (pyruvate → oxaloacetate)
  • Acetyl-CoA carboxylase (acetyl CoA → malonyl CoA)
  • Propionyl-CoA carboxylase (propionyl-CoA → methylmalonyl-CoA)
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14
Q

CYP Inducers

A
  • Carbamazepine
  • Barbiturates
  • Phenytoin
  • Rifampin
  • Griseofulvin St John’s wort
  • Modafinil
  • Cyclophosphamide
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15
Q

CYP Inhibitors?

A
  • Amiodarone
  • Cimetidine
  • Fluoroquinolones
  • Clarithromycin
  • Azole antifungals
  • Grapefruit juice
  • Isoniazid
  • Ritonavir (protease inhibitors)
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16
Q

Pyruvate Dehydrogenase Deficiency

A
  • Buildup of pyruvate that gets shunted to lactate (via LDH) and alanine (via ALT)
  • X-linked
  • Neurologic deficits, lactic acidosis, increased serum alanine
  • Treat: Ketogenic nutrients (fat, lysine, leucine)
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17
Q

Essential Fructosuria

A
  • Defect in fructokinase
  • AR, benign, asymptomatic
  • Fructose appears in blood & urine
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18
Q

Hereditary Fructose Intolerance

A
  • Deficiency of aldolase B
  • AR
  • Fructose-1-phosphate accumulates causing decrease in available phosphate. Inhibition of glycogenolysis and gluconeogenesis.
  • Sx follow consuming fruit, juice or honey
  • Urine dipstick neg (no glucose), Reducing sugars in urine
  • Hypoglycemia, Jaundice, Cirrhosis, Vomiting
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19
Q

Galactokinase Deficiency

A
  • Deficiency of galactokinase
  • Galactitol accumulates, mild, AR
  • Galactosemia, Galactosuria
  • Infantile cataracts, failure to track objects or develop social smile
20
Q

Classic Galactosemia

A
  • Absence of galactose-1-phosphate uridyltransferase
  • AR
  • Sx begin with feeding
  • Failure to thrive, jaundice, hepatomegaly, infantile cataracts (galactitol), intellectual disability, E coli sepsis
21
Q

Ornithine Transcarbamylase Deficiency

A
  • X linked recessive
  • Evident infirst few days of life
  • Excess carbamoyl phosphate converted to orotic acid (part of pyrimidine synthesis pathway)
  • Increased orotic acid in blood and urine, less BUN, hyperammonemia
  • NO MEGALOBLASTIC ANEMIA (vs. orotic aciduria)
22
Q

Phenylketonuria

A
  • ↓Phenylalanine hydroxylase or ↓BH4
  • Tyrosine becomes essential, ↑ Phenylalanine
  • Intellectual disability, growth retardation, seizures, fair skin, eczema, musty body odor
  • Treat: ↑ dietary Tyrosine, ↓ phenylalanine, avoid aspartame (containe Phe)
  • Maternal PKU - microcephaly, intellectual disability, growth retardation, heart defects
23
Q

Maple Syrup Urine DIsease

A
  • AR, Blocked degradation of branched amino acids (Isoleucine, Leucine, Valine)
  • ↓ branched-chain α-ketoacid dehydrogenase (B1)
  • CNS defects, intellectual disability, death, poor feeding, vomiting, urine smells like maple syrup
24
Q

Alkaptonuria

A
  • Congenital deficiency of homogentisate oxidase in the degradative pathway of tyrosine to fumarate (pigment forming homogentisic acid accumulates)
  • AR, usually benign
  • Blue-black connective tissue, cartilage, and sclerae
  • Urine turns black on standing
  • Arthralgias (toxic to cartilage)
  • Treat: Restrict dietary Phe & Tyr
25
Q

Homocystinuria

A
  • Cystathione Synthase Deficiency
  • ↓ Affinity of Cystathione cynthase for pyridoxal phosphate
  • Methione synthase deficiency
  • Excess homocysteine in urine, osteoporosis, marfanoid habitus, ocular changes (downward & inward subluxation), cardiovascular effects, kyphosis, intellectual disability
26
Q

Von Gierke disease

A
  • Type I Glycogen storage disease
  • Deficient Glucose-6-phosphatase (in liver)
  • Severe fasting hypoglycemia, ↑↑ Glycogen in liver, ↑ blood lactate, ↑ triglycerides, ↑ uric acid (Gout) and hepatomegaly
  • Treat: frequent oral glucose/cornstarch, avoid fructose & galactose
27
Q

Pompe disease

A
  • Type II Glycogen storage disease
  • Deficient α-1,4-glucosidase
  • Cardiomegaly, hypertrophic cardiomyopathy, hypotonia, exercise intolerance, early death, large tongue
  • “PomPe trasher the PumP“ (1,4)
28
Q

Cori disease

A
  • Type III Glucogen storage disease
  • Deficient Debranching enzyme (α-1,6-glucosidase)
  • Milder form of von Gierke w/ normal blood lactate levels, accumulation of limit dextran-like structures in cytosol (muscle involvement, milder hypoglyceia)
  • Gluconeogenesis in tact
29
Q

McArdle Disease

A
  • Type IV Glycogen Storage Disease (AR)
  • Deficient skeletal muscle glycogen phosphorylase (Myophosphorylase)
  • ↑ Glycogen in muscle but muscle cannot break it down, painful muscle cramps, myoglobinuria with strenuous exercise, arrhythmia from electrolyte abnormalities
  • Second wind phenomenon during exercise due to increased musculra blood flow
  • Normal blood glucose
  • Mcardle = Muscle
30
Q

Tay Sachs

A
  • AR Lysosomal storage disease
  • Deficient: Hexosaminidase A
  • Accumulated: GM2 Ganglioside
  • Sx: Progressive neurodegeneration, developmental delay, “cherry-red” spot on macula, no HSM (vs. Niemann-Pick)
31
Q

Fabry disease

A
  • XR Lysosomal storage Disease
  • Deficient: α-galactosidase A
  • Accumulated: Ceramide trihexoside
  • Peripheral neuropathy, angiokeratomas, hypohidrosis (Late - progressive renal failure, cardiovascular disease)
32
Q

Metachromatic Leukodystrophy

A
  • AR Lysosomal storage disease
  • Deficient: Arylsulfatase A
  • Accumulated: Cerebroside sulfate
  • Central and peripheral demyelination with ataxia, dementia
33
Q

Krabbe disease

A
  • AR lysosomal storage disease
  • Deficient: Galactocerebrosidase
  • Accumulated: Galactocerebroside, psychosine
  • Peripheral neuropathy, destruction of oligodendrocytes, developmental delay, optic atrophy, globoid cells
34
Q

Gaucher Disease

A
  • AR Lysosomal storage disease
  • Deficient: Glucocerebrosidase
  • Accumulated: Glucocerebroside
  • Most common LSD, hepatosplenomegaly, pancytopenia, osteoporosis, avascular necrosis of femur, bone crises, Gaucher cells (lipid laden macrophages resembling crumpled tissue paper)
35
Q

Niemann-Pick disease

A
  • AR Lysosomal storage disease
  • Deficient: Sphingomyelinase
  • Accumulated: Sphingomyelin
  • Progressive neurodegeneration, hepatosplenomegaly, foam cells, “cherry red” spot on the macula
36
Q

Hurler syndrome

A
  • AR lysosomal stroage disease (mucopolysaccharidoses)
  • Deficient: α-L-iduronidase
  • Accumulated: Heparan sulfate, dermatan sulfate
  • Developmental delay, gargoylism, airway obstruction, corneal clouding, hepatosplenomegaly
37
Q

Hunter Syndrome

A
  • XR Lysosomal storage disease (Mucopolysaccharidoses)
  • Deficient: Iduronate 2 sulfatase
  • Accumulated: Heparan sulfate, dermatan sulfate
  • Mild Hurler + aggressive behavior (no corneal clouding)
38
Q

Systemic Primary Carnitine Deficiency

A
  • Inherited deficiency in transport of LCFAs into the mitochondria, toxic accumulation
  • Weakness, hypotonia, and hypoketotic hypoglycemia
39
Q

Mediam Chain Acyl-CoA Dehydrogenase deficiency

A
  • Decreased ability to break down fatty acids into acetyl-CoA
  • Accumulation of fatty acyl carnitines in the blood w/ hypoketotic hypoglycemia
  • Causes vomiting, lethargy, seizures, coma, liver dysfunction (can lead to sudden death in infants/children)
  • Treat by AVOIDING FASTING
40
Q

Abetalipoproteinemia

A
  • AR - absent chylomicrons, VLDL, LDL
  • Deficiency in ApoB48, ApoB100
  • Infants present w/ severe fat malabsorption, steatorrhea, failure to thrive
  • Later manifestations - retinitis pigmentosa, spinocerebellar degeneration (deficient vit E), ataxia, acantholysis
  • Treat: restrict long-chain fatty acids, oral vitamin E
41
Q

Hyperchylomicronemia

A
  • AR deficiency of lipoprotein lipase or apolipoprotein C-II
  • Increased chylomicrons, TG, cholesterol
  • Pancreatitis, hepatosplenomegaly, eruptive/pruritic xanthomas (no ↑ atherosclerosis risk)
  • Creamy layer in supernatant
42
Q

Familial Hypercholesterolemia

A
  • AD, absent or defective LDL receptors
  • Incerased blood LDL, cholesterol, (sometimes VLDL)
  • Accelerated atherosclerosis (early MI), tendon xanthomas, corneal arcus
  • Heterozygotes = 300, Homozygotes 700+
43
Q

Dysbetalipoproteinemia

A
  • AR, defective Apo E (can’t clear remnants)
  • Increased chylomicrons, VLDL
  • Premature atherosclerosis, tuberoeruptive xanthomas, xanthoma striatum palmare
44
Q

Hypertriglyceridemia

A
  • AD, hepatic overproduction of VLDL
  • Increased VLDL, TG
  • Hypertriglyceridemia (>1000) can cause acute pancreatitis
45
Q

What parts of metabolism occur in mitochondria?

A
  • Fatty acid oxidation (β-oxidation)
  • Acetyl-CoA production
  • TCA cycle
  • Oxidative phosphorylation
  • Ketogenesis
  • Heme synthesis, Urea cycle, Gluconeogenesis are in BOTH mito & cytoplasm (“hugs take two”)
46
Q

What parts of metabolism are in the cytoplasm?

A
  • Glycolysis
  • HMP shunt
  • Synthesis of steroids (SER)
  • Proteins (ribosomes, RER)
  • Fatty acids
  • Cholesterol
  • Nucleotides
  • Heme synthesis, Urea cycle, Gluconeogenesis (“Hugs take two”)

STEP 1 (6 decks)

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