Urea Cycle Disorders Flashcards Preview

x_NeuroGenetics Review > Urea Cycle Disorders > Flashcards

Flashcards in Urea Cycle Disorders Deck (7)
Loading flashcards...
1
Q

N-Acetylglutamate Synthase deficiency (NAGS)

A
  • Autosomal recessive
  • Lethargy, persistent vomiting, poor feeding, hyperventilation, enlarged liver, seizures
  • Total deficiency - symptoms appear immediately following birth
  • Partial deficiency - may occur later in life following a stressful event such as infection
  • Low cirtulline levels, normal orotic acid levels
2
Q

Carbamyl phosphate synthetase deficiency (CPS)

A
  • Autosomal recessive
  • Lethargy, coma, seizures, vomiting, poor feeding, hyperventilation, heptaomegaly
  • Total deficiency - symptoms appear immediately following birth
  • Partial deficiency - symptoms appear in childhood
  • Low citrulline levels, normal orotic acid levels
3
Q

Ornithine transcarbamylase deficiency (OTC)

A
  • X-linked
  • Most common
  • Lethargy, coma, seizures, vomiting, poor feeding, hyperventilation, hepatomegaly
  • Hemizygote males - onset immediately after birth
  • Hemizygote females - 10% are symptomatic
  • Low citrulline levels, high orotic acid levels
4
Q

Argininosuccinic acid synthetase deficiency (ASS) :)

A
  • Autosomal recessive
  • Lethargy, coma, seizures, vomiting, hyperventilation, poor feeding, hepatomegaly
  • Total deficiency - symptoms appear immediately following birth
  • Partial deficiency - symptoms appear in childhood
  • High citrulline levels, high orotic acid levels
5
Q

Argininiosuccinic acid lyase deficiency (ASL)

A
  • Autosomal recessive
  • Lethargy, coma, seizures, vomiting, hyperventilation, poor feeding, hepatomegaly
  • Total deficiency - symptoms appear immediately following birth
  • Partial deficiency - symptoms appear in childhood
  • High citrulline levels, high orotic acid levels
6
Q

Arginase Deficiency (ARG)

A
  • Autosomal recessive
  • Delayed development, protein intolerance, spasticity, seizures, irritability, vomiting, poor appetite
  • Slower onset, often present with symptoms of muscle weakness, hyperammonemia is rare
  • High citrulline levels, high orotic acid levels
7
Q

Treatment of Urea Cycle Defects

A
  • Goal is to maintain plasma glutamine levels at or near normal (Glutamine represents a storage form of nitrogen that can buffer ammonium)
  • Measure of plasma glutamine levels may be single best guide to therapy (levels can predict hyperammonemia)
  • Restricted intake of dietary protein
  • Activation of other waste nitrogen pathways - CPS, OT, ASS - sodium phenylbutyrate activates phenylacetylglutamine - new vehicle for removal of waste nitrogen
  • Arginine supplementation in ASS and ASL
  • Ammonul medication
  • Liver transplant in severe phenotypes