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Flashcards in AA Catabolism Deck (19)
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1

describe the biochemical defect in PKU

2

the most severe IQ decline seen in PKU patients is in ______ (timeline)

the most severe IQ decline seen in PKU patients is in the first few days

3

describe the treatment of PKU

  • avoidance of phenylalanine
  • sapropterin (synthetic form of BH4) may be used in some PKU patients
    • typically mild or moderate forms of the disease

4

describe maternal PKU syndrome

  • women with PKU must maintain low Phe levels before conception and during pregnancy
    • strict adherence must be maintained prior to conception and throughout preg.
  • high maternal blood Phe leads to fetal defects
    • micrcephaly
    • lack of mental dev.
    • congenital heart defects
  • elevated Phe levels has teratogenic properties

5

describe alkaptonuria pathway

6

alkaptonuria is caused by a deficiency in ____

alkaptonuria is caused by a deficiency in homogentisic acid oxidase

7

_____ accumulates in alkaptonuria

homogentisic acid accumulates in alkaptonuria

8

describe tyrosinemia type I aka tyrosinosis

  • deficiency of fumaryl acetoacetate hydrolase
  • build up of fumaryl-acetoacetate
    • metabolized to another compound that causes kidney and liver damage
      • cabbage like odor of the urine

9

contrast the urine in PKU, alkaptonuria, maple syrup urine disease and tyrosinemia type I

PKU = mousey odor of urine

alkaptonuria = black/brown discoloration of urine (due to homogentisic acid)

maple syrup urine disease = maple syrup odor of urine

tyrosinemia type I = cabbage like smell to urine

10

describe the biochemical pathway defect in MSUD

11

_____ is deficient in maple syrup urine disease

branched chain alpha-keto acid dehydrogenase 

12

describe treatment of MSUD

  • dietary restriction of branched chain amino acids--leucine, isoleucine, valine
  • dietary supplementation with TPP (vit. B1) may be useful in patients that have an enzyme with low coenzyme affinity

13

describe methylmalonyl CoA mutase deficiency

  • results in elevated levels of methylmalonic acid (MA) in circulation
  • causes metabolic acidosis due to the accumulation of MA
  • associated with neurological manifestations, seizures, encephalopathy

14

in some children with methylmalonyl CoA mutase deficiency, there is improvemetn with _____ supplementation

in some children with methylmalonyl CoA mutase deficiency, there is improvemetn with vit. B12 (cobalamin) supplementation

15

describe the methylmalonyl CoA mutase deficiency pathway

16

describe homocystinuria

  • deficiency of cystathionine B-synthase (transulfuration pathway)
  • a group of disorders in which there is a defect in homocysteine metabolism
  • characterized by high plasma and urinary levels of homocysteine
  • homocysteine binds to connective tissue and disrputs structure
    • characterized by dislocation of lens, skeletal abnormalities, delay of mental dev
  • some patients respond to oral vit. B6

17

homocystinuria is caused by a deficiency in ______

homocystinuria is caused by a deficiency in cystathionine B-synthase

18

describe the pathway of homocystinuria

19

what are two potential fates of homocysteine?

methionine and cysteine