Week 15

Question 1

glucogenic amino acid

Answer 1

An amino acid that can be converted into glucose via gluconeogenesis.

Question 2

ketogenic amino acid

Answer 2

An amino acid that can be converted into ketone bodies or fatty acids.

Question 3

Which amino acids are exclusively ketogenic?

Answer 3

Leucine and lysine.

Question 4

Which amino acids are nonessential?

Answer 4

Amino acids that can be synthesized by the body (e.g., alanine, aspartate, asparagine, glutamate, glutamine, glycine, proline, serine, tyrosine, cysteine). (*require Phe and Met respectively)

Question 5

What are the substrates for nonessential amino acid production?

Answer 5

Intermediates of glycolysis and the TCA cycle (e.g., pyruvate, oxaloacetate, α-ketoglutarate).

Question 6

Cause of albinism (most common type, complete OCA)?

Answer 6

Tyrosinase deficiency → impaired conversion of tyrosine to melanin.

Question 7

Health problems associated with albinism?

Answer 7

Hypopigmentation, visual impairment, photophobia, nystagmus, increased risk of skin cancer.

Question 8

Management/treatment of albinism?

Answer 8

No cure; sun protection, vision correction, regular skin and eye exams.

Question 9

Cause of PKU?

Answer 9

Phenylalanine hydroxylase (PAH) deficiency → inability to convert phenylalanine to tyrosine.

Question 10

What are classic and non-classic PKU?

Answer 10

Classic PKU: PAH deficiency. Non-classic PKU: tetrahydrobiopterin (BH4) deficiency or dihydropteridine reductase defect.

Question 11

Symptoms of PKU?

Answer 11

Intellectual disability, seizures, microcephaly, hypopigmentation, musty odor, growth failure.

Question 12

Diagnostic method for PKU and when is it done?

Answer 12

Newborn screening (blood phenylalanine level) at 24–48 hours after birth.

Question 13

Management/treatment of PKU?

Answer 13

Low-phenylalanine diet, avoid aspartame, tyrosine supplementation, BH4 in some cases.

Question 14

Cause of homocystinuria?

Answer 14

Cystathionine β-synthase deficiency (impaired methionine → cysteine pathway).

Question 15

Types of homocystinuria?

Answer 15

Vitamin B6-responsive and B6-nonresponsive forms.

Question 16

Symptoms of homocystinuria?

Answer 16

Lens dislocation, skeletal abnormalities, thrombosis, osteoporosis, intellectual disability.

Question 17

Diagnostics of homocystinuria?

Answer 17

High homocysteine and methionine in blood and urine.

Question 18

Management/treatment of homocystinuria?

Answer 18

Vitamin B6, B12, folate supplementation; low-methionine diet; cysteine supplementation.

Question 19

Cause of MSUD (maple syrup urine disease)?

Answer 19

Branched-chain α-ketoacid dehydrogenase (BCKD) deficiency.

Question 20

Symptoms of MSUD?

Answer 20

Poor feeding, vomiting, ketoacidosis, neurologic signs, seizures, maple-syrup odor of urine.

Question 21

Diagnostic approach to MSUD?

Answer 21

Newborn screening showing elevated branched-chain amino acids (leucine, isoleucine, valine).

Question 22

Treatment/management of MSUD?

Answer 22

Diet low in branched-chain amino acids; special formula; thiamine in responsive forms.