Amino Acid Diseases

Question 1

Due to low phenylalanine hydroxylase or tetrahydrobiopterin (BH4) cofactor

Answer 1

PKU

Question 2

Tyrosine becomes essential.

Answer 2

PKU

Question 3

Findings: intellectual disability, growth retardation, seizures, fair complexion, eczema

Answer 3

PKU

and musty body odor.

Question 4

tetrahydrobiopterin supplementation is needed

Answer 4

PKU

Question 5

Disorder of aromaticamino acid metabolism

Answer 5

PKU

causes musty body odor

Question 6

patients must avoid the artificial sweetener aspartame

Answer 6

PKU

Question 7

Blocked degradation of branched amino acids (Isoleucine, Leucine, Valine) due to deficiency of branched-chain
α-ketoacid dehydrogenase (needs Vit. B1).

Answer 7

Maple Syrup Urine

Question 8

Increased α-ketoacids in the blood, especially those of leucine.

Answer 8

Maple Syrup Urine

Question 9

thiamine (Vit. B1) supplementation is needed

Answer 9

Maple Syrup Urine

Question 10

vomiting, poor feeding, urine smells like burnt sugar. Causes severe CNS defects, intellectual disability, death.

Answer 10

Maple Syrup Urine

Question 11

Congenital deficiency of homogentisate oxidase in the degradative pathway of tyrosine to fumarate
pigment-forming homogentisic acid builds up in tissue
GRAYISH-BLUE-ASHEY skin lesions

Answer 11

Alkaptonuria

I’ll capture all of you. I’m TyRed of FUMing over you turning the gentle homo black and blue”

Question 12

bluish-black connective tissue, ear cartilage, and sclerae (ochronosis);
urine turns black on prolonged exposure to air.
May have debilitating arthralgias (homogentisic acid toxic to cartilage).

Answer 12

Alkaptonuria

Question 13

Osteoporosis, Marfanoid habitus,
Ocular changes (downward and inward lens subluxation), Cardiovascular effects
(thrombosis and atherosclerosis stroke and MI),
kyphosis,
intellectual disability,
fair complexion

Answer 13

Homocystinuria

lens subluxes “down and in”
(vs Marfan, “up and out”).

Question 14

a condition that leads to hypercoagulability and thromboembolic occlusion.

Can cause acute coronary syndrome in Children (MIs)
Ectopic lens
Mental retardation

Answer 14

homocystinuria

Question 15

Hereditary defect of renal PCT and intestinal amino acid transporter that prevents reabsorption of Cystine, Ornithine, Lysine, and Arginine (COLA).

Answer 15

Cystinuria

Question 16

Excess cystine in the urine can lead to recurrent precipitation of what stones

Answer 16

Hexagonal

Question 17

Most commonly present in infancy with poor feeding, vomiting,
hypotonia,
high anion gap metabolic acidosis,
hepatomegaly,
seizures.
Organic acid accumulation: ketoacidosis &/or hyperammonemia

Answer 17

Propionic Acidemia
or
Methylmalanic Acidemia
----------
Deficiency of propionyl-CoA carboxylase
Deficiency of methylmalonyl-CoA mutase or vitamin B12

Maple syrup = NO AMMONEMIA

Question 18

Treatment: low-protein diet limited in Valine, Odd-chain fatty acids, Methionine, Isoleucine, Threonine (VOMIT).

Answer 18

Propionic Acidemia
Methylmalanic Acidemia
or
Maple Syrup

*technically Thymadine and Uracil are not supposed to be given either

Question 19

Methylmalanic Acidemia is caused by

what enzyme
or
What Vitamin Deficiency?

Answer 19

Deficiency of

methylmalonyl-CoA mutase
or
vitamin B12

Question 20

Propionic Acidemia is caused by

what enzyme and vitamin deficiency

Answer 20

Deficiency of propionyl-CoA carboxylase

Vit B7 Biotin dependent

Question 21

_____ is caused by impaired transport of neutral amino acids in the small intestine and proximal tubule of the kidney. Symptoms include pellagra-like skin eruptions and cerebellar ataxia, which occur as a result of _____ deficiency.

Answer 21

Hartnup disease

niacin (Vit B3)

Question 22

a urea cycle enzyme that produces urea and ornithine from arginine. A deficiency results in progressive spastic diplegia (paresis), growth delay, and abnormal, choreoathetoid movements.
Present with no (or mild) hyperammonianemia.

Answer 22

Arginase

Treatment includes an arginine-free, low-protein diet.

Question 23

Deficiencies of vitamins ______(3) are associated with hyperhomocysteinemia, which in turn is associated with atherosclerosis and thrombotic events.

Answer 23

B6, B12, and folate (B9)

Question 24

Orotic aciduria (AR) disorder of de novo pyrimidine synthesis that occurs due to a defect in ________ enzyme.

Children typically present with 
physical and mental retardation, 
megaloblastic anemia
elevated urinary orotic acid 
No ammonemia 

______ supplementation can improve symptoms

Answer 24

uridine 5’-monophosphate (UMP) synthase

Uridine

(Uridine to UMP via nucleoside kinases)

Question 25

The hydroxylation of proline and lysine residues in collagen helps it attain its maximum tensile strength. This process occurs in the ________ and requires vitamin C as a cofactor. Impaired collagen synthesis resulting from vitamin C deficiency (scurvy) can lead to fragile vessels, predisposing to _______, ecchymosis, and petechia.

Answer 25

rough endoplasmic reticulum

Bleeding gums

*coiled corkscrew hair can also be seen (nasty)

Question 26

________ can be used to treat homocystinuria, which is caused by a defect in _________.

This condition is characterized by elevated homocysteine levels, ectopia lentis, intellectual disability, Marfanoid body habitus, and increased occurrence of thromboembolic events.

Answer 26

Pyridoxine (vitamin B6)

Cystathionine synthase (vitamin B6-dependent)

Question 27

Cysteine becomes essential

Answer 27

Homocysteinuria

Question 28

Can have cardiovascular effects
thrombosis
atherosclerosis 
stroke
MI

Answer 28

Homocysteinuria

Question 29

Can cause Hypermethonemia

Answer 29

Homocysteinuria

Question 30

Pyruvate carboxylase catalyzes the initial step in ___ by converting pyruvate to oxaloacetate.

Answer 30

gluconeogenesis

Requires B7 (Biotin)

Question 31

Ornithine transcarbamylase catalyzes the combination of ornithine and carbamoyl phosphate to form____ in the urea cycle.

Answer 31

citrulline

• This reaction occurs within the mitochondria.

Question 32

Ornithine transport into mitochondria is necessary for the urea cycle. Defects typically cause neurological damage due to hyperammonemia.

______ restriction improves this condition by reducing the amount of amino acid turnover.

Answer 32

Protein

Question 33

Alanine transfers amino group to ____ for glucose synthesis as well

Answer 33

Alpha Ketoglutarate

Question 34

Patients with ___ disorders typically have discrete episodes of vomiting, tachypnea, and confusion/coma secondary to hyperammonemia (a metabolic emergency).

Answer 34

urea cycle (Arginase deficiency)

*Ornithine transcarbamylase deficiency is the most common disorder of the urea cycle

Question 35

Examination shows scaly, erythematous skin lesions in sun-exposed areas and cerebellar ataxia.
Child is pruritic and irritable.

Laboratory evaluation shows increased levels of neutral amino acids in the urine.

Diagnosis

Answer 35

Hartnup

Vit B3 deficiency (Niacin)