Inborn Errors of Galactose and Fructose Metabolism

Question 1

GALT deficiency (neonatal) symptoms and clinical presentation

Answer 1

symptoms triggered by lactose/galactose in diet
Neonatal clinical presentation
- hyperbilirubinemia
- jaundice
- liver dysfunction
- cataracts
- sepsis
- brain damage --> mental status, vomiting, etc

Question 2

Galactosemia consequences

Answer 2

clinical liver disease, jaundice

Question 3

Galactosemia suspected; what to do?

Answer 3

cataracts –> slit eye exam
sepsis evaluation
measure bilirubin
urinalysis

Question 4

Issues with GALT newborn screening

Answer 4

false positives and negatives
delay in reporting vs onset of symptoms
NOT a diagnosis

follow up with quantitative RBC, GALT enzyme activity, or mutational analysis

Question 5

GALT outcomes: lactose-related

Answer 5

Neonatal liver disease
Neonatal sepsis
Cataracts
Renal proximal tubule dysfunction
Neurologic outcomes varied
- speech difficulties
- spatial orientation or motor difficulties
- leukodystrophy

Question 6

GALT outcomes: lactose-independent

Answer 6

cirrhosis
Lenticular scarring
verbal dyspraxia
ovarian dysfunction
intellectual function

Question 7

GALT chronic management

Answer 7

Diet: lactose restriction, calcium supplements

Monitor GAL-1-P levels, urinary galactitol

Follow up with opthamology, language and developmental assessments, endocrine/ovarian function

Question 8

Galactosemia dietary restriction; dietary management

Answer 8

lactose milk disaccharide: Glu+Gal
exclude lactose from infant formula
avoid lactose and dairy
galactose in fruits and veggies (soy)

TO EAT:
non-dairy proteins
calcium supplements
multivitamins
soy formula
Emmentaler cheese

Question 9

Galactokinase deficiency

• symptoms
• biochemistry
• treatment

Answer 9

SYMPTOMS: cataracts

BIOCHEM:
- glycosuria
- high gal, urine galacitol
low/normal Gal-1-P

TREATMENT

• eliminate dairy products
• monitor blood galactose, urine galactitol

Question 10

Galactose Epimerase (GALE) deficiency

• symptoms
• biochemistry
• management

Answer 10

severe, similar to GALT deficiency
psychomotor retardation
milder variants, benign effect

BIOCHEM:

• glycosuria
• high gal, gal-1-P, urine galacitol
• normal GALT activity

difficult management (bc galactose is indispensible)

Question 11

HFI diagnosis (Hereditary fructose intolerance)

• genetics
• management

Answer 11

GENETICS
aldolase B, chrom 9
multiple causative mutations

fructose-loading is dangerous

MANAGEMENT
eliminate fructose from diet, avoid sucrose, sorbitol, mannose, invert sugar
danger of IV infusions or oral meds in emergency room

Question 12

Fructose-1,6-biphosphatase deficiency

• 2 groups
• acute presentation/symptoms

Answer 12

2 types: newborn onset (more severe), later-onset (mild or severe)

PRESENTATION

• hepatomegaly
• hypoglycemia
• lactic acidosis
• ketosis

symptoms triggered by intercurrent illness, fast, fructose/sucrose ingestion
tolerance to fasting increases with age

Question 13

Fructose-1,6-biphosphatase deficiency symptoms

Answer 13

symptoms triggered by intercurrent illness, fast, fructose/sucrose ingestion
tolerance to fasting increases with age