Metabolic Disorders Flashcards
How do metabolic disorders often present?
Normal at birth
Early: Acidosis, poor feeding, vomiting, lethargy
Late: MR, organomegaly, body odors
What are the disorders of amino acid metabolism? (4)
PKU
Homocystinuria
Maple Syrup Urine Disease
Hartnup’s Disease
What is the defect in PKU?
Deficiency of phenylalanine hydroxylase (or its cofactor tetrahydrobiopterin)
Cannot turn phenylalanine into tyrosine
What accumulates in PKU?
Phenylalanine and metabolites
MR, fair hair and skin, blue eyes, eczema and mousy/musty body odor
PKU - AR
What is the etiology of homocysteinemia/uria?
Deficiency of cystathionine synthase
or
Defect of Me-cobalamin formation or Me-THF reductase
What are the s/sx or homocysteinuria?
FTT, delay
Ectoipa lentis, marfanoid body habitus, MR osteoporosis
**Dx at 3 years
High methionine and homocysteine
How do you treat homocysteinuria?
High dose B6 +/- Folic acid
Restrict methionine intake
Betaine if unresponsive to B6
Ectopia lentis
Subluxation of the lens
Iridodonesis = quivering iris
Myopia
What is the deficiency in Maple Syrup Urine Disease
Deficiency of branched chain ketoacid DH
Leucine, isoleucine and valine build up
S/sx of MSUD
High plasma leucine
Poor feeding/vomiting/lethargy
Hypertonicity and flaccidity
Hartnup Disease
Deficiency in transport of neutral amino acids in intestines and renal tubules
What is the difference between Hartnup’s Disease and Fanconi’s?
Urinary proline, hydroxyproline, and arginine remain normal in Hartnup
How do you dx and treat Hartnup’s Disease?
DX: Aminoaciduria: alanine, serine, threonine, valine, leucine etc.
Normal plasma aa levels
Treat: Nicotinic acid and high protein diet
**Symptoms from tryptophan deficiency
