Genetic Metabolic Disorders

Question 1

PKU

Answer 1

(disorder of AA met)

• Phenylketonuria
• Deficiency of phenylalanine hydroxylase
• Phe not metabolized into tyrosine

Question 2

PKU MNT

Answer 2

• restrict Phe
• supp Tyr
• monitor blood Phe levels
• 3 day food/formula record prior to blood tests

Question 3

Maternal PKU

Answer 3

(disorder of AA met)

- fetus exposed to higher amounts of Phe

Question 4

Maternal PKU MNT

Answer 4

MNT is complex (need essential AA for dev., but too much = suboptimal brain dev)

• Monitor blood Phe
• limit Phe while providing adequate nutrients
• medical food with Phe removed

Question 5

Maple syrup urine disease

Answer 5

(disorder of AA met)
AKA branched-chain ketoaciduria

• branched chain alpha ketoaciduria hydroxidase complex (BCAKD)
• inability to metabolize BCAAs especially leucine

leu, ile, val

Question 6

Maple syrup urine disease MNT

Answer 6

• Monitor BCAA levels and growth
• special formula supplemented with infant formula or breast milk
• gradually reintroduce BCAAs when Leu decreased

Question 7

Proprionic acidemia

Answer 7

(Disorder of organic acid met)

• defect of proprionyl-CoA carboxylase
• end up with a buildup of proprionic acid in the blood

Question 8

Proprionic acidemia MNT

Answer 8

pharmacologic doses of biotin

Question 9

Methylmalonic acidemia

Answer 9

(disorder of organic acid met)

• defect of methylmalonyl-CoA mutase apoenzyme
• end up with build-up of methylmalonic acid

Question 10

Methylmalonic acidemia MNT

Answer 10

pharamcologic doses of B12 > to help the enzyme function optimally

Question 11

Ketone utilization disorders

Answer 11

(disorder of organic acid met)

- disorders of isoleucine and ketone body metabolism

Question 12

Ketone utilization disorders MNT

Answer 12

• restrict dietary protein
• supplement with L-carnitine
• Avoid fasting

L-carnitine > helps remove fatty acids metabolites in the blood and promotes their excretion

Question 13

Ornithine transcarbamylase (OTC) deficiency

Answer 13

(disorders of urea cycle met)

Question 14

Citrullinemia

Answer 14

(disorders of urea cycle met)

Question 15

Arginosuccinic aciduria

Answer 15

(disorders of urea cycle met)

Question 16

Carbamyl-phosphate synthetase deficiency

Answer 16

(disorders of urea cycle met)

Question 17

MNT for Disorders of urea cycle metabolism

Answer 17

• Restrict PRO and only use BV PRO
• Infant PRO- 1-1.5g/kg/d
• Child- 1-2g/kg/d
• Supp- L- arginine unless arginase def
• Arginine helps excrete excess nitrogen

Question 18

Galactosemia

Answer 18

(disorder of CHO met)

• inability to convert galactose to glucose
• build-up of galactose in the bood

Question 19

Galactosemia MNT

Answer 19

• avoid lactose-containing products and certain fruits and vegetables
• soy infant formula

Question 20

Examples of galactose containing F&V

Answer 20

Dates
papayas
bell peppers
persimmons
tomatoes
watermelon

Question 21

Glycogen storage disease

Answer 21

(Disorder of CHO met)

• inability to metabolize glycogen to glucose
• Hypoglycemia

Question 22

Glycogen storage disease MNT

Answer 22

• High complex CHO diet (also equal distribution throughout the day)
• cornstarch administration and iron supplementation (cornstarch can inhibit iron absorption)

Question 23

Medium-chain acyl CoA dehydrogenase deficiency (MCAD)

Answer 23

(disorders of fatty acid oxidation)
- lack of enzymes to break down MCFAs

• Happens when fasting or ill
• Hypoglycemia
• Absence of urinary ketones

Question 24

Long-chain 3-hydroxyacyl-CoA dehydrogenase deficiency (LCAD)

Answer 24

(disorders of fatty acid oxidation)
- lack of enzyme to break down LCFAs

• Happens when fasting or ill
• Hypoglycemia
• Absence of urinary ketones

Question 25

MNT for disorders of fatty acid oxidation

Answer 25

• avoid fasting
• use three meals plus snacks (especially before bed)
• use high CHO, low fat diet
• supplement with L-carnitine (helps with fatty acid oxidation; removes toxic metabolites from bloodstream through urine)