Amino Acid Disorders

Question 1

What is a weird thing that patients with PKU have to stay away from?

Answer 1

aspartame, artificial sweetener

Question 2

What are the symptoms of PKU?

Answer 2

ID
growth retardation
seizures
fair skin
eczema
musty body odor

Question 3

What are the findings in the baby of a mom w/ PKU who doesn’t manage her diet during pregnancy?

Answer 3

microcephaly
ID
growth retardation
congenital heart defects

Question 4

HOw is maple syrup urine disease inherited? What is the defect?

Answer 4

autosomal recessive
defective alpha ketoacid dehydrogenase (can’t break down branched AA)
get buildup of isoleucine, leucine, valine
I Love Vermont Maple Syrup from maple trees (branched)

Question 5

What are the symptoms of maple syrup urine disease?

Answer 5

sweet smelling urine
CNS defects, ID
death

Question 6

What is the defect in alkaptonuria?

Answer 6

aka ochronosis
deficiency of homogentisate oxidase
can’t convert tyrosine–>homogentisic acid–>(homogentisic oxidase)–>maleylacetoacetic acid–>fumarate–>TCA

Question 7

What is the inheritance of alkaptonuria? What are the symptoms?

Answer 7

autosomal recessive
darkly pigmented
dark CT, brown sclera, urine turns black when exposed to air
arthralgias
Think Al Capone in Dark Suit

Question 8

What is the treatment for alkaptonuria?

Answer 8

Vit C, avoid phenylalanine, tyrosine

Question 9

Describe the pathways that start w/ homocysteine.

Answer 9

#1: homocysteine-->methionine via homocysteine methyltransferase, B12. Methionine-->SAM
#2: homocysteine-->cystathione via cystathione synthase, B6, serine. Cystathione-->Cysteine

Question 10

What is required to make SAM?

Answer 10

Methionine
ATP
THF
B12

Question 11

What is the inheritance pattern of all types of homocysteinuria?

Answer 11

aut recessive

Question 12

What are the findings in homocysteinuria?

Answer 12

increased homocysteine in urine
ID
osteoporosis
kyphosis
tall
lens subluxation (downward)
thrombosis, atherosclerosis

Question 13

Aside from homocysteinuria, what other condition has lens subluxation? Which direction?

Answer 13

Marfan–subluxation of lens upward. Pompous Michael Phelps.

Homocysteinuria–subluxation downward. Humble.

Question 14

What defect leads to cystinuria? Inheritance?

Answer 14

autosomal recessive

COLA. defect in renal PCT and intestinal AA transporters to absorb cysteine, ornithine, lysine, arginine.

Question 15

What is the diagnostic test for cystinuria? Finding? Main treatment?

Answer 15

diagnosis: urinary cyanide-nitroprusside test
hexagonal cysteine kidney stones
acetazolamide, alkalization of the urine