Genetics- Metabolic Disorders of the newborn- Dr. Adkison Flashcards Preview

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Flashcards in Genetics- Metabolic Disorders of the newborn- Dr. Adkison Deck (38)
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1
Q

where are Housekeeping genes expressed?

A

in all cell types. expressed all the time and regulated

2
Q

giving a recombinant enzyme, glucocerebrosidase, for a pt w/ Type 1 Gauchers is an example of what method of treating inherited enzyme mutation?

A

replacement of mutant protein

3
Q

what are the essential amino Acids?

A

PVT. TIM HALL

phenylalanine, valine, tryptophan, threonine, isoleucine, methionine, histidine, arginine, leucine, lysine

4
Q

increased amounts of what in urine causes a mousey odor of the urine? what disorder is this seen in?

A

Phenylalanine- in Phenylketonuria

5
Q

a kid presents with light har, bluish eyes, microcephaly, likes to sit in a unusual “tailor” position and has an IQ of 29. what disorder is this classic presentation of?

A

Phenylketonuria

6
Q

Phenylketonuria is a mutation in what enzyme?

A

phenylalanine hydroxylase

7
Q

Clinical expectations with PKU type 1?

A

elevated phenylalanine, reduced or normal tyrosine, normal at birth, toxic to infant neurological tissue. damage occurs after birth (0-6 months)

8
Q

what is the Guthrie test? whats a positive outcome?

A

bacterial inhibition assay that tests for PKU. >4mg/100dL then suspect PKU

9
Q

what do PKU patients have to limit their intake in their diet?

A

Phenylalanine

10
Q

what else causes a positive Guthrie test?

A

high PHE, High TYR (low birth weight, protein formula, vit. C deficiency) liver disease, Galactosemia

11
Q

If positive Guthrie test reveals elevated PHE. what should you perform next? what result is a typical PKU patient?

A

blood test. >15mg/100ml PHE and <5 mg/100ml TYR

12
Q

Major clinical finding in type 2 hyperphenylalanine?

A

abnormal response to diet. progressive detioration of brain fxn leading to death

13
Q

what is deficient in TYPE 2 hyperphenylalanine? what is it required for?

A

Dihydropteridine Reductase

BH4 synthesis, required for tyrosine and tryptophan pathways –> neurotransmitters

14
Q
elevated PHE
reduced or normal TYR 
reduced BH4
elevated BH2 
dopamine, serotonin levels low 
what disorder has this clinical presentation?
A

type 2 hyperphenylalanemia

15
Q
elevated neopterin 
reduced sepiapterin 
reduced BH4
reduced BH2 
elevated PHE
A

TYPE 3 hyperphenylalanemia

16
Q

offspring with mental retardation and microcephaly due to maternal PKU, is due to what mechanism?

A

PHE crosses the placenta and Phenylalanine hydroxylase from fetal liver is unable to convert to tyrosine

17
Q

what inheritence is PKU?

A

autosomal recessive

18
Q

what is the mildest form of phenylalanine hydroxylase deficiency?

A

non- PKU HyperPhenylAlanine

19
Q

a child presents with dark urine and increased levels of homogentistic acid?

A

Alkaptonuria

20
Q

Alkaptonuria is a deficiency in what enzyme?

A

homogentisic acid oxidase

21
Q

what is a deficiency in tyrosinase?

A

Albinism. can’t form melanins from tyrosine

22
Q

what are the activities of tyrosinease in Type 1A classic albinism? and Type 1B classic albinism?

A

1A- tyrosinase activity is negative

1B- activity is reduced

23
Q

what is the most common form of albinism in the world? what is the activity of tyrosinase?

A

albinism type 2

activity is positive

24
Q

what is present in type 2 to differentiate it from type 1B?

A

presence of pigmented nevi. (difficult to ID in blacks.) hair will be yellow or very light colored

25
Q

what is the deficient enzyme in Tyrosinemia?

A

p-hydroxyphenypyruvic oxidase

26
Q

what is secreted in the urine in Tyrosinemia? whats high in newborns blood?

A

p-hydroxyphenylpyruvic acid

high tyrosine in blood

27
Q

what is type 2 Tyrosinemia?

A

oculocutaneous tyrosinemia- photphobia and conjuctivitis during first year due to tyrosine crystals.

28
Q

what enzyme is deficient in Homocystinuria?

A

cystathionine-B-synthase

29
Q

what is in the urine in Homocystinuria?

A

homocystine and methionine

30
Q

what are the clinical features of Homocystinuria?

A
tall, long limbs
dislocated lens (ectopia lentis)- downward 
vascular abnormalities 
development and mental delay may occur and skeletal abnormalities
31
Q

what disease presents with elevated BCAAs and alpha ketoacids in the urine?

A

Maple Syrup Urine Disease

32
Q

what should you restrict in the diet of a MSUD patient?

A

protein- Branched chain amino acids

33
Q

Classic Galactosemia is a mutation in what?

A

galactose-1-phosphate uridyl transferase

34
Q

Nonclassical galactosemia is a mutation in what?

A

Galactokinase

35
Q

what is galactose important for?

A

cell membranes and lipids- especially the brain

36
Q

what are infants with Galactosemia unable to utilize?

A

galactose found in milk

37
Q

what do infants w/ Galactosemia develop?

A

mental retardation and cataracts, failure to thrive. (all in a few weeks)

38
Q

treatment of galactosemia?

A

restrict galactose in diet immediately. Only early diagnosis makes symptoms disappear.