METABOLIC DEFECTS IN AMINO ACID METABOLISM

Question 1

characterized by elevated blood levels of
phenylalanine and phenylpyruvate

Answer 1

Phenylketonuria

Question 2

If untreated, the disease leads to mental retardation, physical disabilities, and even death

Answer 2

MSUD

Question 2

caused by a deficiency of phenylalanine hydroxylase

Answer 2

Phenylketonuria

Question 3

a rare (1:185,000), autosomal recessive disorder in which there is a partial or complete deficiency in branched-chain α-keto acid dehydrogenase

Answer 3

Maple syrup urine disease (MSUD)

Question 4

refers to a group of conditions in which a defect in tyrosine metabolism results in a deficiency in the production of melanin

Answer 4

Albinism

Question 5

PKU

Answer 5

Phenylketonuria

Question 6

Maple syrup urine disease (MSUD) is a rare (1:185,000), autosomal recessive disorder in which there is a partial
or complete deficiency in branched-chain

Answer 6

α-keto acid dehydrogenase

Question 6

MSUD

Answer 6

Maple syrup urine disease

Question 7

Phenylketonuria (PKU), is caused by a deficiency of

Answer 7

phenylalanine hydroxylase

Question 8

an enzyme complex that decarboxylates
leucine, isoleucine, and valine

Answer 8

α-keto acid dehydrogenase

Question 9

Albinism refers to a group of conditions in which a defect in tyrosine metabolism results in a deficiency in the production of

Answer 9

melanin

Question 10

most common clinically
encountered inborn error of amino acid metabolism (prevalence 1:15,000)

Answer 10

Phenylketonuria (PKU)

Question 11

characterized by feeding problems,
vomiting, dehydration, severe metabolic acidosis, and a characteristic maple syrup odor to the urine

Answer 11

Maple syrup urine disease (MSUD)

Question 12

result in the partial or full absence of pigment from the skin, hair, and eyes

Answer 12

Albinism

Question 13

characterized by
accumulation of phenylalanine (and a deficiency of tyrosine)

Answer 13

Phenylketonuria (PKU)

Question 14

They are at increased risk for skin cancer

Answer 14

Albinism

Question 15

Treatment includes restriction of methionine intake and supplementation with
vitamins B6, B12, and folate

Answer 15

Homocystinuria

Question 16

appears in different forms, and it may be inherited by one of several modes: autosomal recessive (primary mode), autosomal dominant, or X-linked

Answer 16

Albinism

Question 17

group of disorders involving defects in the metabolism of homocysteine

Answer 17

Homocystinuria

Question 17

a rare metabolic condition involving a deficiency in homogentisic acid oxidase, resulting in the accumulation of homogentisic acid

Answer 17

Alkaptonuria

Question 18

results from a deficiency of copper-requiring tyrosinase, causing a total absence of pigment from the hair, eyes, and skin

Answer 18

Complete albinism

Question 19

diseases are inherited as autosomal recessive illnesses, characterized by high plasma and urinary levels of homocysteine and
methionine and low levels of cysteine

Answer 19

Homocystinuria

Question 20

Alkaptonuria has three characteristic symptoms, namely:

Answer 20

homogentisic aciduria large joint arthritis
black ochronotic pigmentation of cartilage and collagenous tissue.

Question 21

Complete albinism is also known as

Answer 21

tyrosinase-negative oculocutaneous albinism

Question 22

most common cause of homocystinuria

Answer 22

defect in the enzyme
cystathionine β-synthase, which converts homocysteine to cystathionine

Question 23

tyrosinase-negative oculocutaneous
albinism is also known as

Answer 23

Complete albinism

Question 23

Individuals who are homozygous for
cystathionine β-synthase deficiency exhibit

Answer 23

ectopia lentis
skeletal abnormalities
tendency to form thrombi osteoporosis
neurological deficits

Question 24

displacement of the lens of the eye

Answer 24

ectopia lentis

Question 25

most severe form of the condition

Answer 25

Complete albinism