Inborn Error Of Metabolism Flash Cards

Question 1

What are inborn errors of metabolism (IEM)?

Answer 1

A group of genetic disorders caused by enzyme deficiencies affecting metabolic pathways.

Question 2

What is the mode of inheritance of most inborn errors of metabolism?

Answer 2

Autosomal recessive.

Question 3

What are common symptoms of inborn errors of metabolism?

Answer 3

Failure to thrive, developmental delay, vomiting, lethargy, and metabolic acidosis.

Question 4

Which screening test is used for newborns to detect inborn errors of metabolism?

Answer 4

Newborn metabolic screening (tandem mass spectrometry).

Question 5

What is the biochemical basis of phenylketonuria (PKU)?

Answer 5

Deficiency of phenylalanine hydroxylase leading to accumulation of phenylalanine.

Question 6

What are the clinical features of untreated PKU?

Answer 6

Intellectual disability, seizures, musty odor, light skin, and eczema.

Question 7

What is the dietary management of PKU?

Answer 7

Low-phenylalanine diet and supplementation with tyrosine.

Question 8

What enzyme is deficient in maple syrup urine disease (MSUD)?

Answer 8

Branched-chain alpha-keto acid dehydrogenase.

Question 9

What is the hallmark biochemical feature of MSUD?

Answer 9

Accumulation of branched-chain amino acids (leucine, isoleucine, valine).

Question 10

What is the characteristic odor of maple syrup urine disease?

Answer 10

Sweet, maple syrup-like odor in urine.

Question 11

What is the treatment for MSUD?

Answer 11

Dietary restriction of branched-chain amino acids and thiamine supplementation.

Question 12

What enzyme is deficient in alkaptonuria?

Answer 12

Homogentisate oxidase.

Question 13

What is the characteristic finding in alkaptonuria?

Answer 13

Dark urine that turns black on standing due to homogentisic acid accumulation.

Question 14

What is the long-term complication of alkaptonuria?

Answer 14

Ochronosis (bluish-black pigmentation of connective tissues) and arthritis.

Question 15

What enzyme deficiency causes homocystinuria?

Answer 15

Cystathionine beta-synthase (CBS) deficiency.

Question 16

What are the clinical features of homocystinuria?

Answer 16

Marfanoid habitus, lens dislocation (downward), thrombosis, intellectual disability.

Question 17

What is the treatment for homocystinuria?

Answer 17

Vitamin B6, folate, vitamin B12, and methionine restriction.

Question 18

What enzyme is deficient in galactosemia?

Answer 18

Galactose-1-phosphate uridyltransferase (GALT).

Question 19

What are the symptoms of galactosemia?

Answer 19

Jaundice, cataracts, hepatomegaly, failure to thrive, vomiting, hypoglycemia.

Question 20

What dietary modification is required for galactosemia?

Answer 20

Eliminate lactose and galactose from the diet (avoid dairy products).

Question 21

What enzyme is deficient in fructose intolerance?

Answer 21

Aldolase B.

Question 22

What are the symptoms of hereditary fructose intolerance?

Answer 22

Hypoglycemia, vomiting, hepatomegaly, failure to thrive after fruit consumption.

Question 23

What is the dietary management of hereditary fructose intolerance?

Answer 23

Avoid fructose, sucrose, and sorbitol.

Question 24

What enzyme is deficient in glycogen storage disease type I (Von Gierke disease)?

Answer 24

Glucose-6-phosphatase.

Question 25

What are the clinical features of Von Gierke disease?

Answer 25

Severe fasting hypoglycemia, hepatomegaly, lactic acidosis, hyperuricemia.

Question 26

What is the treatment for Von Gierke disease?

Answer 26

Frequent feedings with cornstarch and avoiding fasting.

Question 27

What enzyme is deficient in Pompe disease (GSD II)?

Answer 27

Lysosomal acid alpha-glucosidase.

Question 28

What are the clinical features of Pompe disease?

Answer 28

Cardiomegaly, hypotonia, hepatomegaly, early death in infantile form.

Question 29

What enzyme is deficient in McArdle disease (GSD V)?

Answer 29

Muscle glycogen phosphorylase.

Question 30

What are the clinical features of McArdle disease?

Answer 30

Exercise intolerance, muscle cramps, myoglobinuria after exercise.

Question 31

What is the defective enzyme in Tay-Sachs disease?

Answer 31

Hexosaminidase A.

Question 32

What is the characteristic finding in Tay-Sachs disease?

Answer 32

Cherry-red macula, neurodegeneration, no hepatosplenomegaly.

Question 33

What enzyme is deficient in Niemann-Pick disease?

Answer 33

Sphingomyelinase.

Question 34

What is the characteristic finding in Niemann-Pick disease?

Answer 34

Cherry-red macula, hepatosplenomegaly, foam cells.

Question 35

What enzyme is deficient in Gaucher disease?

Answer 35

Glucocerebrosidase.

Question 36

What are the characteristic features of Gaucher disease?

Answer 36

Hepatosplenomegaly, bone crises, lipid-laden macrophages (Gaucher cells).

Question 37

What is the enzyme deficiency in Fabry disease?

Answer 37

Alpha-galactosidase A.

Question 38

What are the clinical features of Fabry disease?

Answer 38

Angiokeratomas, neuropathic pain, renal failure, cardiovascular disease.

Question 39

What enzyme is deficient in Lesch-Nyhan syndrome?

Answer 39

HGPRT (hypoxanthine-guanine phosphoribosyltransferase).

Question 40

What are the characteristic symptoms of Lesch-Nyhan syndrome?

Answer 40

Self-mutilation, gout, intellectual disability, dystonia.

Question 41

What is the enzyme deficiency in adrenoleukodystrophy?

Answer 41

ATP-binding cassette transporter (ABCD1) defect leading to VLCFA accumulation.

Question 42

What are the clinical features of adrenoleukodystrophy?

Answer 42

Adrenal insufficiency, neurological deterioration, progressive demyelination.

Question 43

What enzyme is deficient in Krabbe disease?

Answer 43

Galactocerebrosidase.

Question 44

What are the clinical features of Krabbe disease?

Answer 44

Peripheral neuropathy, optic atrophy, developmental delay.

Question 45

What enzyme is deficient in metachromatic leukodystrophy?

Answer 45

Arylsulfatase A.

Question 46

What are the clinical features of metachromatic leukodystrophy?

Answer 46

Demyelination, ataxia, dementia, peripheral neuropathy.

Question 47

What is the defective enzyme in Hurler syndrome?

Answer 47

Alpha-L-iduronidase.

Question 48

What are the clinical features of Hurler syndrome?

Answer 48

Gargoylism, corneal clouding, hepatosplenomegaly, developmental delay.

Question 49

What is the defective enzyme in Hunter syndrome?

Answer 49

Iduronate-2-sulfatase.

Question 50

What is the difference between Hunter and Hurler syndrome?

Answer 50

Hunter syndrome has no corneal clouding and has milder symptoms.

Question 51

What is the treatment for urea cycle disorders?

Answer 51

Protein restriction, ammonia scavengers, arginine/citrulline supplementation.

Question 52

What enzyme deficiency causes ornithine transcarbamylase (OTC) deficiency?

Answer 52

OTC enzyme deficiency leading to hyperammonemia.

Question 53

What are the symptoms of hyperammonemia?

Answer 53

Lethargy, vomiting, cerebral edema, encephalopathy.

Question 54

What is the biochemical marker of methylmalonic acidemia?

Answer 54

Elevated methylmalonic acid and metabolic acidosis.

Question 55

What is the treatment for propionic acidemia?

Answer 55

Low-protein diet, biotin supplementation, ammonia scavengers.

Question 56

What is the primary defect in Zellweger syndrome?

Answer 56

Peroxisome biogenesis disorder leading to VLCFA accumulation.

Question 57

What is the characteristic sign of Zellweger syndrome?

Answer 57

Severe hypotonia, seizures, liver dysfunction, early death.