PKU Clinical Correlation

Question 1

If a child is untreated for PKU, when do symptoms of the disease start becoming apparent?

Answer 1

6 months you can see developmental and growth delay in the children

Question 2

What are some cutaneous symptoms of PKU?

Answer 2

Pigment Dilution, lighter skin and eyes

Question 3

What is the mode of inheritance for PKU?

Answer 3

Autosomal Recessive

Question 4

What does phenylalanine get converted to to as it begins building up in PKU (2 things)?

Answer 4

1. Hydroxyphenylacetic Acid
2. Phenylacetic Acid

**Collectively these are called phenylketones

Question 5

What is significant about phenylalanine being an essential amino acid?

Answer 5

You can cut back on it and the body won’t be able to make more

Question 6

What enzyme is deficient in PKU?

Answer 6

Phenylalanine Hydroxylase

Question 7

When do you start to see elevated levels of phenylketones in newborns with PKU?

Answer 7

1 month

Question 8

What is the site of dysfunction in PKU?

- Site of damage?

Answer 8

• Liver = major enzyme dysfunction

- CNS = major site of damage

Question 9

If a baby has PKU should you limit all of the phenylalanine in their diet?

Answer 9

NO - its essential to have all amino acids so small amounts should be given

Question 10

What is the maximum amount of time a newborn can go without being screened in a hospital?

Answer 10

48 hours, for normal kids its 24 hours

Question 11

What would you expect to see on the mass spectrum of an individual affected by PKU, that was untreated?

Answer 11

• HIGH - Phe

- LOW - Tyr

Question 12

T or F: females with PKU don’t have to worry about their disease affecting their children

Answer 12

False, All females have a maternal effect where their elevated levels of PKU will have a negative affect on the child, also the disease is autosomal recessive so it could be passed on

Question 13

What two requisites classify an individual as having classical PKU?

Answer 13

• > 20 mg% Phe
• Tyr normal to low
• Phenylketones present

Question 14

What does the following individual have:

4-10 mg% phe
Tyr normal, Phenylketones negative
untreated with no cognitive impairment

Answer 14

Non-PKU Hyperphenylalaninemia (HPA)

Question 15

What does the following individual have?

10-20mg% phe
Tyr normal, Phenylketones variable

Answer 15

Variant PKU

Question 16

Which individuals are most likely to respond to BH4 treatment?

Answer 16

Those with the milder forms like HPA and Variant PKU

Question 17

T or F: all PKU is a phe Hydroxylase defect

Answer 17

False

Question 18

What are some other causes of PKU? (name 5)

Answer 18

1. Hypertyrosinemia
2. Immature Liver
3. Total Parenteral Nutrition (TPN) - excess amounts of Phe in IV
4. Increased Conc. of Blood on the Spot
5. Cofactor abnormalities

Question 19

What percentage of PKU cases result from common mutations?

- Private Mutations?

Answer 19

• Common Mutations - 30-50% cases

- Private Mutations - 50-70% cases

Question 20

If people are BH4 responsive what modifications can you make to their diet?

Answer 20

• You don’t have to be so harsh

Question 21

LOOK AT THESE SLIDES AGAIN BEFORE EXAM

Answer 21

_________

Question 22

T or F: the mother’s circulating metabolites can hurt the fetus if she has PKU

Answer 22

True