Confirmatory Testing of Metabolic Diseases and NBS Flashcards
What is the asocarnitine profile of SCAT?
elevated C4 peak
What is the asocarnitine profile of MCAT?
elevated C6, C8, and C10:1
What is the asocarnitine profile of VLCAT?
elevated C14
What are the most prominent peaks on a normal asocarnitine profile?
C2 (most common), C14, and C16
What conditions are associated with elevated C3 peaks on an asocarnitine profile?
propionic acidemia
MMA
Cbl disease
SUCLA2 deficiency
What condition is associated with an elevated C4 isobutyryl peak on an asocarnitine profile?
isobutyrylCoA dehydrogenase deficiency (IBDH)
What conditions are associated with elevated C5 peaks on an asocarnitine profile?
isovaleric acidemia (IVA) (isovaleryl isomer also associated with leucine) 2-methylbutyrylCoA dehydrogenase deficiency (2MBG) (2-methylbutyryl isomer also associated with isoleucine)
What conditions are associated with elevated C5-OH peaks on an asocarnitine profile?
3-methylcrotonylcoA dehydrogenase deficiency (3-MCC) and bitonidase (3-hydroxyisovaleryl isomer)
3-ketothiolase deficiency (BTK) (C5:1) and 2-methyl-3-hydroxybutyric aciduria (2-CH3-3-OH-Butyryl isomer)
What conditions are associated with elevated C8, C6, C10, and C10:1 peaks on an asocarnitine profile?
medium chain acylCoA dehydrogenase deficiency (MCAD) (octanoyl isomer)
What conditions are associated with elevated C14:1 peaks on an asocarnitine profile?
very long chain acylCoA dehydrogenase deficiency (VLCAD) (tetradecenoyl isomer)
What is isovaleric acidemia (IVA)?
deficiency of isovalerylCoA dehydrogenase accumulates isovalerylcarnitine (C5), isovaleric acid, 3-hydroxyisovaleric acid, isovalerylglycine
What is 3-MCC?
deficiency of 3-methylcrotonylCoA carboxylase
most common organic acidemia; clinically benign
accumulates 3-hydroxyisovalerylcarnitine (C5-OH), 3-hydroxyisovaleric acid, and 3-methylcrotonylglycine
secondary carnitine deficiency
What is maternal 3-MCC?
when a baby is picked up on NBS for 3-MCC and the mother is tested and it is her that carries the deficiency, not they child
What is 3-ketothiolase deficiency?
deficiency of beta-ketothiolase
disorder or isoleucine and ketone bodies leading to accumulation of tiglylcarnitine (C5:1), 2-methyl-3-hydrobutyrylcarnitine (C5-OH), 2-methyl-3-hydroxybutyrate, 2-methylacetoacetate, and tiglylcarnitine
clinical halmark: ketoacidosis
What is propionic acidemia?
deficiency of propionylCoA carboxylase
PCCA and PCCB genes
accumulation of propionylcarnitine (C3), 3-hydroxypropionate, propionylglycine, tiglylglycine, and methylcitrate
clinical features include severe metabolic acidosis, hyperammonemia, ketotic hyperglycinemia, seizures, failure to thrive, developmental delay, bone marrow suppression
Why are propionylCoA accumulations toxic?
inhibit pyruvate carboxylase and trans-mitochondrial malate shuttle (impaired gluconeogenesis –> hypoglycemia)
inhibition of glycine clevage comples (hyperglycinemia)
Inhibition of carbamyl phosphase synthase (CPS) and N-acetylglutamate synthase (impaired urea cycle –> hyperammonemia)
What is methylmalonic acidemia?
deficiency of MUT
accumulation of propionylcarnitine, methylmalonic acid, 3-hydroxypropionic acid, and methylcitric acid
elevation of C3
What are the enzyme, gene, biomarkers, and features for Pompe disease?
acid alpha-glucosidase GAA urine Glc4 and blood CK glycogen storage in muscle (all) hypertrophic cardiomyopathy, hypotonia, respiratory failure, death before first year of life without treatment (classic infantile onset pompe disease)
What are the enzyme, gene, and biomarkers for MPS-1?
A-iduronidase
IDUA
GAG (DS, HS)
What are the enzyme, gene, and biomarkers for Fabry disease?
A-galactosidase A
GLA
Lyso-Gb3
What are the enzyme, gene, and biomarkers for Gaucher disease?
B-glucosidase
GBA
Lyso-GL1
What are the enzyme, gene, and biomarkers for Krabbe disease?
galactoylceramidase
GALC
psychosine
What are the enzyme, gene, and biomarkers for Niemann-Pick A/B?
Acid sphingomyelinase
SMPD1
Lyso-SPM
