[Met/Sugar/basic]
What compositions of monosaccharides for disaccharides?
Sucrose
Lactose
Maltose
Sucrose: Glucose + Fructose (table sugar)
Lactose: Glucose + Galactose (milk sugar)
Maltose: Glucose + Glucose
[Met/Sugar/Gal]
Three types of galactosemia?
Classic galactosemia (Enzyme activity 0 or barely detectable)
Clinical variant galactosemia (Mostly < 10-15%, around 1%)
Duarte variant galactosemia (No difference than general population)
[Met/Sugar/Gal]
Presentation for untreated infants with classic galactosemia? (4)
- Feeding problems, failure to thrive
- Hepatocellular damage
- Bleeding
- E. coli sepsis
[Met/Sugar/Gal]
Complications for treated galactosemia? (2)
- Developmental delays, speech problems (termed childhood apraxia of speech and dysarthria), abnormalities of motor function
- Hypergonadatropic hypogonadism or premature ovarian insufficiency (POI) (almost all female)
[Met/Sugar/Gal]
Major differences in clinical variant galactosemia compared to classic galactosemia?
- Commonly affected population
- Time of diagnosis
- Complications
- African Americans and native Africans in South Africa
- Not easily detected by newborn screening (hypergalactosemia is not as high)
- No long-term complications such as neurologic or premature ovarian insufficiency
[Met/Sugar/Gal]
Classic galactosemia
Enzyme defect?
Causal gene?
Galactose-1-phosphate uridylyltranserase
GALT
[Met/Sugar/Gal]
Classic galactosemia
Enzyme defect?
Causal gene?
Galactose-1-phosphate uridylyltranserase
GALT
[Met/Sugar/Gal]
Common variants for galactosemia
Classical (2)
Clinical variant (1)
Duarte (1)
Classical: Q188R (m/c, European), 5.2 kb del (Ashkenazi Jewish)
Clinical variant: S135L (African American)
Duarte variant: N314D
[Met/Sugar/Gal]
Biochemical finding in classic galactosemia and clinical variant galactosemia? (3)
Elevated erythrocyte galactose-1-phosphate concentration
Increased Urine galactitol
Decreased GALT enzyme activity
[Met/Sugar/Gal]
Usual erythrocyte galactose-1-phosphate concentration in classic galactosemia?
Erythrocyte galactose-1-phosphate is usually >10 mg/dL
[Met/Sugar/Gal]
Biochemical tests in newborn screening for galactosemia? (2)
Erythrocyte GALT enzyme activity (Most states)
+/- Blood total galactose level (Some, might miss clinical variant galactosemia)
[Met/Sugar/Gal]
Acute management for galactosemia?
Immediate galactose restriction upon screening positive
[Met/Sugar/Gal]
Chronic complication for galactosemia despite galactose-free diet?
No effect of treatment (3)
If delayed treatment (2)
No effect of treatment
1. Verbal dyspraxia
2. Ovarian dysfunction
3. Intellectual function (>50% may have ↓IQ)
If delayed treatment,
1. Cirrhosis
2. Lenticular scarring
[Met/Sugar/Gal]
Chronic management for galactosemia except galactose-free diet? (3)
Developmental assessment
Hormonal replacement for possible primary ovarian failure for puberty
Supplement of calcium, vitamin D, and vitamin K
[Met/Sugar/Gal]
Three enzyme deficiencies in galactose metabolism?
- Galactosemia (Galactose-1-phosphate uridyltransferase (GALT))
- Galactokinase deficiency
- Uridine diphosphate (UDP) -galactose-4-epimerase (GALE) deficiency
[Met/Sugar/Gal]
Characteristics of galactokinase deficiency? (2)
Cataracts
Asymptomatic
[Met/Sugar/Gal]
Characteristics of generalized form of Uridine diphosphate (UDP) -galactose-4-epimerase (GALE) deficiency? (2)
Similar to galactosemia
Additional hypotonia and deafness
[Met/Sugar/Fructosuria]
Characteristics of Benign Fructosuria? (3)
- Cause
- Presentation
- Implication
- Deficiency of fructokinase
- No clinical manifestations
- Incidental finding
[Met/Sugar/HFI]
Enzyme defect in hereditary fructose intolerance?
Fructose 1-phosphate aldolase
[Met/Sugar/HFI]
Which sugars to trigger hereditary fructose intolerance? (3)
Fructose
Sucrose
Sorbitol
[Met/Sugar/HFI]
Biochemical findings of untreated Hereditary Fructose Intolerance? (6)
- Glucose, organic acid, electrolytes (3), protein
Hypoglycemia
Lactic acidemia
Hypermagnesemia
Hypophosphatemia
Hyperuricemia
Hyperalaninemia
[Met/Sugar/HFI]
Clinical findings of untreated Hereditary Fructose Intolerance? (3)
Upon exposure, usually after weaning of breast feeding
Nausea, vomiting, and abdominal distress
Chronic growth restriction / failure to thrive
[Met/Sugar/HFI]
Causal gene for Hereditary Fructose Intolerance?
ALDOB (aldolase B)
[Met/Sugar/HFI]
Diagnostic test for Hereditary Fructose Intolerance? (2)
Mostly from genetic testing ALDOB
Rarely deficient hepatic fructose 1-phosphate aldolase (aldolase B) activity on liver biopsy
