Step 1 Biochem Enzyme Deficiencies

Front 1

glycogen storage diseases

Back 1

all result in abnormal glycogen metabolism and accumulation of glycogen within cells

Hint 1

T

Front 2

Von Gierke;s disease (type I)
deficient enzyme:
findings:

Back 2

deficient enzyme: glucose 6-phosphatase (converts glucose 6 phosphate to glucose)
findings: severe hypoglycemia, increase glycogen in liver and kidneys. lactic acidosis, hepatomegaly, renomegaly
- increased cholesterol, TGs, and uric acid

Front 3

Pompe's disease (type II)
deficient enzyme:
findings:

Back 3

deficient enzyme: lysosomal alpha-1,4 glucosidase (acid maltase)
findings: cardiomegaly

Front 4

Cori's disease (type III)
deficient enzyme:
findings:

Back 4

deficient enzyme: alpha 1,6 glucosidase (debranching enzyme)
findings: milder form of type I with normal lactate levels

Front 5

mcardle's disease
deficient enzyme:
findings:

Back 5

deficient enzyme: skeletal muscle glycogen phosphorylase
findings: can't break down glycogen in muscle, painful muscle cramps, myoglobinuria with strenous exercise

Front 6

lysosomal storage diseases

Back 6

deficiency in lysosomal enzymes which results in accumulation of abnormal metabolic products

Front 7

FAbry's disease
deficient enzyme:
accumulated substrate:

Back 7

deficient enzyme: Alpha galactosidase A
accumulated substrate: ceramide trihexoside
peripheral neuropathy of hands/feet, angiokeratomas, cardio & renal disease

Front 8

Gaucher's disease
deficient enzyme:
accumulated substrate:

Back 8

deficient enzyme: beta- glucerebrosidase
accumulated substrate: glucocerebroside
hepatosplenomegaly, aseptic necrosis of femur, Gaucher's cells (macrophages that look like crimpled tissue paper

Front 9

Niemann-Pick disease
deficient enzyme:
accumulated substrate:

Back 9

deficient enzyme: sphingomyelinase
accumulated substrate: sphingomyelin
neurodegeneration, hepatosplenomegaly, cherry red spot on macula

Front 10

Tay-Sachs disease
deficient enzyme:
accumulated substrate:

Back 10

deficient enzyme: hexosaminidase A
accumulated substrate: GM2 ganglioside
neurodegeneration, developmental delay, cherry spot on macula, lysosomes with onion skin

Front 11

Krabbe's disease
deficient enzyme:
accumulated substrate:

Back 11

deficient enzyme: galactocerebrosidase
accumulated substrate: galactocerebroside
peripheral neuropathy, optic atrophy, globoid cells

Front 12

metachromic leukodystrophy
deficient enzyme:
accumulated substrate:

Back 12

deficient enzyme:arylsulfatase A
accumulated substrate: cerebroside sulfate
central and peripheral demyelination with ataxia & dementia

Front 13

Hurler's syndrome
deficient enzyme:
accumulated substrate:

Back 13

deficient enzyme: alpha-L-iduronidase
accumulated substrate: heparan sulfate, dermatan sulfate
developmental delay, gargoylism, airway obstruction, corneal clouding

Front 14

Hunter's syndrome
deficient enzyme:
accumulated substrate:

Back 14

deficient enzyme: iduronate sulfatase
accumulated substrate: heparan sulfate, dermatan sulfate
milder form of Hurler's

Front 15

pyruvate kinase deficiency

Back 15

associated with hemolytic anemia

Front 16

pyruvate dehyrogenase deficiency

Back 16

- pyruvate dehydrogenase converts pyruvate to acetyl CoA
- backup of pyruvate & alanine results in lactic acidosis
- neurological defects
- tx: increase ketogenic nutrients (lysine, leucine)

Front 17

G6PD deficiency

Back 17

- glucose-6-phosphaet dehydrogenase needed to keep glutathione reduced which in turn detoxifies free radical and peroxides
- leads to hemolytic anemia
- heinz bodies/ bite cells

Front 18

fructose intolerance

Back 18

- deficiency in aldolase B
- fructose-1-phosphate accumulates causing a decrease in available phosphate and inhibition of glycogenolysis and gluconeogenesis
- hypoglycemia, jaundice, cirrhosis

Front 19

essential fructosuria

Back 19

-deficiency in fructokinase
- benign condition
- fructose in urine

Front 20

classic galactosemia

Back 20

- absence of galactose-1-phosphate uridlytransferase (converts galactose to glucose)
- galactose accumulates causing infantile cataracts, hepatomegaly, failure to thrive, mental retardation
-exclude galactose & glucose from diet

Front 21

galactokinase deficiency

Back 21

- deficiency in galactokinase
- galacticol accumulates and appears in blood/urine.
- infatile cataracts, more mild than the other condition

Front 22

OTC deficiency

Back 22

- no ornithine transcarbamoylase
-interferes with body's ability to eliminate ammonia
-excess carbamoyl phosphate is converted to orotic acid which accumulates in blood/urine
- decreased BUN, hyperammonemia

Front 23

PKU=phenylketonuria

Back 23

- decreased phenylalanine hydroxylase (converts phenylalanine to tyrosine)
-tyrosine becomes essential
-increased phenylalanine leads to phenyketones in urine
- musty body odor, retardation, fair skin

Front 24

alkaptonuria

Back 24

- deficiency of homogentisic acid oxidase
- benign condition
- urine turns black on standing
- may have really bad arthralgias

Front 25

albinism

Back 25

- deficiency of tyrosinase OR defectice tyrosine transporters
- low tyrosine meanse low melanin

Front 26

homocystinuria

Back 26

- deficiency in cystathione synthase (converts homocysteine to cytsathione which then becomes cysteine)
- OR defect in homocysteine methyltransferase
- retardation, homocysteine in urine, tall stature, kyphosis, lens subluxation
-excess homocysteine in urine

Front 27

maple syrup urine disease

Back 27

- decrease alpha-ketoacid dehydrogenase
-blocked degradtion of branched amino acids (isoleucine, valine, leucine)
- increased alpha ketoacids in the blood

Front 28

adenosine deaminase deficiency (purine salvage deficiency)

Back 28

- no adenosine deaminase
- prevents DNA synthesis of lymphocytes
- cause SCID (severe conbined immunodeficiency disease)
- bubble boy

Front 29

Lesch-Nyhan syndrome

Back 29

- absence of hypoxanthine guanine phosphoribosyl transferase (HGPRT)
- excess uric acid production
- retardation, self mutilation, aggression, hyperuricemia. gout

Front 30

orotic aciduria

Back 30

- defect in either orotic acid phosphoribosyltransferase OR orotidine 5'-phosphate decarboxylase
- inabilty to convert orotic acid to UM
- increased orotic acid in urine, megalobalstic anemia that does not improve w/ tx, NO HYPERAMMONEMIA (so don't confuse with OTC def)
- tx: oral uridine

Front 31

porphyrias

Back 31

a set of related conditions in which specific enzymes needed in heme synthesis are defective and proximal intermediates accumulated
Sx: painful abdomen, pink urine, polyneuropathy, psych issues, precipitated by drugs

Front 32

lead poisoning
affected enzyme:
accumulated substrate in urine:

Back 32

affected enzyme: ferrochelatase & ALA dehydratase
accumulated substrate in urine: coproporphyrin & ALA

Front 33

acute intermittent porphyria
affected enzyme:
accumulated substrate in urine:

Back 33

affected enzyme: uroporphyrinogen I synthase
accumulated substrate in urine: porphobilinogen & delta ALA

Front 34

porphyria cutanea tarda
affected enzyme:
accumulated substrate in urine:

Back 34

affected enzyme: uroporphyrinogen decarboxylase
accumulated substrate in urine: uroporphyrin

Front 35

I cell disease

Back 35

- inherited lysosomal storage disorder
- failure of addition mannose-6-phosphate to lysosome proteins. adding mannose-6-phosphate is what tells the protein to go to the lysosome.
-enzymes are secreted outside the cell
-coarse facial features, restricted joint movement, high plasma levels of lysosomal enzymes**