Carbohydrate metabolism

Question 1

Classic GALT variants

Answer 1

Q188R (Caucasian), K285N, 5kb del (AJ)

Question 2

Non-classic GALT variants (2)

Answer 2

N314D (Duarte, unclear if causes disease), S135L (Af Amer)

Question 3

Aspects of Galactosemia not improved with treatment

Answer 3

Verbal dyspraxia, intellectual disability, ovarian dysfunction

Question 4

Cataracts only

Answer 4

GALK deficiency

Question 5

Severe GALE variant, mimics galactosemia

Answer 5

c.280G>A homozygotes

Question 6

Gene for essential fructosuria, benign

Answer 6

Fructokinase

Question 7

Vomiting, lethargy, acute liver dysfunction (jaundice, bleeding, hypoglycemia, acidosis)

Answer 7

Hereditary Fructose Intolerance (aldoB)

Question 8

Hypoketotic hypoglycemia

Answer 8

Fructose-1,6-bisphosphatase deficiency (late onset)

Question 9

Severe ketoacidosis, lactic acidosis, hepatomegaly, hypoglycemia

Answer 9

Fructose-1,6-bisphosphatase deficiency (neonatal onset)

Question 10

Is more often triggered by illness than dietary intake of offending agent

Answer 10

Fructose-1,6-bisphosphatase deficiency

Question 11

Hepatomegaly without dysfunction, profound hypoglycemia w/lactic acidosis, hyperuricemia

Answer 11

GSD1a/Von Gierke: Glucose-6-phosphatase

Question 12

Hepatomegaly without dysfunction, profound hypoglycemia w/lactic acidosis, hyperuricemia, neutropenia and recurrent infection, eventual hepatic adenoma/HCC

Answer 12

GSD1b/Von Gierke: Glucose-6-phosphatase

Question 13

Treatment of GSD1/Von Gierke

Answer 13

Frequent feeds, complex carbs, cornstarch/glycosade, allopurinol, bicarb/citrate, ACE-I +/- G-CSF

Question 14

Growth failure and developmental delay, abdominal distention, hypoketotic hypoglycemia +/- CKemia, eventual cirrhosis/HCC, distal myopathy

Answer 14

GSD2/Cori, Forbes: glycogen debranching enzyme

Question 15

Treatment of GSD2/Cori, Forbes: glycogen debranching enzyme

Answer 15

High protein diet, frequent feeds, ketones

Question 16

Hepatomegaly, mild ketotic hypoglycemia, resolve by adulthood

Answer 16

GSD6/Hers: hepatic glycogen phosphorylase deficiency OR GSD9a: hepatic phosphorylase B-kinase deficiency

Question 17

Ketotic hypoglycemia, post-prandial hyperglycemia w/glycosuria, normal liver size

Answer 17

GSD0a: liver glycogen synthase GYS2

Question 18

??

Answer 18

GSD0b: muscle (ubiquitous) glycogen synthase GYS1

Question 19

Exercise intolerance +/- rhabdomyolysis, with second wind

Answer 19

GSD5/McArdle: muscle phosphorylase

Question 20

Exercise intolerance + hemolysis

Answer 20

GSD7/Tarui: phosphofructokinase

Question 21

WPW in adolescence, hypertrophic cardiomyopathy

Answer 21

AMPK deficiency

Question 22

Cells that make & use glycogen in the brain

Answer 22

Astrocytes synthesize and produce lactate to feed neurons; neurons do not make glycogen

Question 23

Myoclonic epilepsy or absence seizures in adolescence -> dementia, visual loss, apraxia, aphasia -> vegetative and death within a decade

Answer 23

Epilepsy Progressive Myoclonus/Lafora disease: EPM2A or B from accumulation of branched chains in astrocytes

Question 24

DD, hypotonia, epilepsy, ataxia, cerebellar vermis hypoplasia, coagulation abnormalities, abnormal fat distribution, endocrine abnl/FTT

Answer 24

CDG1a: PMM2

Question 25

Risk of hemolytic anemia with fucose treatment

Answer 25

CDG: SLC35C1

Question 26

Liver dysfunction, coagulopathy, diarrhea; tx with mannose

Answer 26

CDG1b: MPI

Question 27

Hypoglycemia, liver disease, coagulopathy, Pierre-Robin, cardio/myopathy, tx with galactose and cornstarch

Answer 27

CDG: PGM1

Question 28

Cataracts, hepatocellular damage/jaundice, hemolysis, coagulopathy renal tubulopathy (Fanconi), neonatal sepsis (E. coli), FTT

Answer 28

Galactosemia (GALT)