Glycogenosis / Questions and case reports

Questions

 * 1) Glycogen biosynthesis
 * 2) * A – requires inorganic phosphate as one of the substrates
 * 3) * B – involves the formation of α-1 → 6 branches by glucan unit transfer from α-1 → 4 bonds
 * 4) * C – includes synthesis of UDP-glucose directly from uridine triphosphate and glucose-6-phosphate
 * 5) * D – involves the transfer of glucose residue in UDP-glucose to the reduced end of the "primer" of glycogen
 * 6) Glucagon acts by:
 * 7) * A – inhibits cAMP - dependent protein kinase in the liver
 * 8) * B – stimulates gglycolysis vin the liver
 * 9) * C – stimulates gluconeogenesis in muscles
 * 10) * D – stimulates glycogen phosphorylase phosphorylation in the liver
 * 11) * E – stimulates glycogen synthase dephosphorylation in the liver
 * 12) Type I glycogenosis (Gierke´s disease) is caused by:
 * 13) * A – hepatic glucose-6-phosphate dehydrogenase deficiency
 * 14) * B – glucose-6-phosphatase deficiency in the liver and kidneys
 * 15) * C – abnormal structure of liver glycogen
 * 16) * D – amylo-1 → 6-glucosidase deficiency in the liver and muscles
 * 17) * E – hepatic phosphorylase deficiency

Newborn slightly hypotrophic, with cyanosis and marked hypoglycemia
It is a newborn born in the 38th week of gestation, 2,100 g (adequate weight: 3,300 g), length 47 cm, slightly cyanotic (for hypoxia), with tachycardia (35 / min). Glycaemia: 0.8 mmol / l (lower limit for newborns: 2.5 mmol / l). Mother 35 years. In the last trimester, she had mild hypertension and recurrent urinary tract infections, vomiting and eating very little.

Questions:
 * 1) What is the cause of such low levels in the newborn?
 * 2) How is the energy metabolism of a fetus defferent from a newborn?

Infant with recurrent hypoglycaemia
An infant with recurrent hypoglycemia from birth was tested with glucagon and 1 hour after a carbohydrate diet. Glycaemia rose from 3.9 mmol / l to 6.1 mmol / l. 3 hours later, the blood glucose dropped to 2.5 mmol / l. However, no increase in blood glucose was observed after further glucagon administration.

Question: What is the cause of this form of glucagon response
 * A – Deficiency of hepatic glycogen phosphorylase or glycogen "mediator"
 * B – Glucose-6-phosphatase deficiency.
 * C – Defect in the glucagon receptor.
 * D – Inability to secrete an adequate amount of glucagon.
 * E – Problem in gluconeogenesis.

Patient with type V glycogenosis (McArdle´s disease) and patient with type VI glycogenosis (Hers´disease)
The cause of both conditions is an inherited deficit of a key glycogen degradation enzyme: glycogen phosphorylase.

Question:
 * 1) Which of these types has more severe clinical symptoms and why?

Related articles
Other chapters from the book MASOPUST, J., PRŮŠA, R .: Pathobiochemistry of metabolic pathways

Source



 * MASOPUST, Jaroslav and Richard PRŮŠA. Pathobiochemistry of metabolic pathways. 1st edition. Prague: Charles University, 1999. 182 pp. 38- 40.  ISBN 80-238-4589-6.