URINE METABOLIC DISORDERS (Phenylalanine-Tyrosine disorders) Flashcards
What type of overflow condition results in increased amino acids in blood and urine?
PKU, MSUD, Cystinosis
What is the renal type aminoaciduria with normal amino acids in blood and increased amino acids in urine?
Cystinuria, Fanconi’s syndrome
What disorders are categorized as phenylalanine-tyrosine disorders?
Phenylketonuria, Tyrosyluria/Tyrosenemia, Alkaptonuria, Melanuria
What gene is absent in Phenylketonuria?
Phenylalanine hydroxylase
What causes other forms of phenylketonuria?
Tetrahydrobiopterin deficiency
What is the odor associated with phenylketonuria?
Mousy urine, sweat, breath odor
What condition may phenylketonuria lead to?
Mental retardation
What is the positive result for the FeCl3 tube test for phenylketonuria?
Blue-green color
What is the positive result for the Phenistix strip test for phenylketonuria?
Gray to gray-green color
What does a positive Guthrie bacterial inhibition test show?
Growth in the media
Which counteracts the action of B2-thienylalanine in the Guthrie bacterial inhibition test?
Phenylalanine
What is the confirmatory test for Phenylketonuria?
Ion exchange HPLC
What is absent in Type 1 tyrosyluria?
Fumarylacetoacetate hydrolase (FAH)
What is absent in Type 2 tyrosyluria?
Tyrosine aminotransferase
What is absent in Type 3 tyrosyluria?
p-hydroxyphenylpyruvic acid dioxygenase
In which condition may tyrosyluria/tyrosinemia also be seen?
Severe liver disease
What is the urine odor in tyrosinemia?
Rancid butter
What is the positive result for the FeCl3 screening test for tyrosinemia?
Transient green
What is the positive result for the Nitroso-napthol screening test for tyrosinemia?
Orange-red
What is the confirmatory test for tyrosinemia?
Chromatography, quantitative serum assay of tyrosine
What testing method is used for error of metabolism?
Tandem mass spectrophotometry (MS/MS)
What enzyme is related to Tyrosinemia type 1b?
Maleylacetoacetic acid isomerase
What enzyme is related to Tyrosinemia type 1a?
Fumarylacetoacetoacetic acid hydrolase
What gene is absent in Alkaptonuria?
Homogentisic acid oxidase
When does urine darken in Alkaptonuria?
After standing at room temperature (alkaline)
What color does Alkaptonuria stain cloth diapers?
Brown or black
What color do disposable plastic diapers stain in Alkaptonuria?
Reddish
What pigmentation does homogentisic acid cause in connective tissues and ears in Alkaptonuria?
Black pigment (onchronosis)
What is the treatment for Alkaptonuria?
Vitamin C
What is the accumulation of Homogentisic Acid Oxidase in connective tissue called?
Onchrosis
What are the positive results for the FeCl3, Clintest, and Silver nitrate tests for Alkaptonuria?
FeCl3 - transient blue, Clintest - yellow ppt, Silver nitrate - black color
What is the confirmatory test for Alkaptonuria?
Paper/Thin layer chromatography
Capillary electrophoresis
GC-MS
What condition causes melanuria?
Melanoma
What substance does melanoma secrete to oxidize melanogen to melanin?
5,6-dihydroxyindole
When does urine darken in melanuria?
Upon oxidation (air exposure)
What condition can melanuria lead to due to deficient melanin production?
Albinism
What are the positive results for the screening tests for melanuria?
FeCl3 - gray/black ppt
Sodium nitroprusside - red color
Ehrlich test - red color
