Type VI Glycogenosis (Hers Disease, Hepatophosphorylase Insufficiency)

What is Type VI Glycogenosis (Herce’s Disease, Hepatophosphorylase Insufficiency)?

Type VI glycogenosis (Hers disease, hepatophosphorylase insufficiency) – glycogenosis caused by liver phosphorylase deficiency.

Pathogenesis during Type VI Glycogenosis (Herce’s Disease, Hepatophosphorylase Insufficiency)

Liver phosphorylase catalyzes the phosphorylation (cleavage) of glycogen to form glucose-1-phosphate. Violation of this mechanism leads to excessive deposition of glycogen in the liver.

According to Gers, type VI glycogenosis is any glycogenosis in which there is a normal activity of amylo-1,6-glucosidase and glucose-6-phosphatase. The activity of phosphorylases is sharply reduced, sometimes it is normal, but they never reveal its complete absence. This is a particularly important group of glycogenoses, since it makes up all cases of glucogenoses.

Theoretically, this group includes 6 subgroups:

  1. with the absence of structural anomalies of liver phosphorylase;
  2. with a complete absence or decrease in the activity of I phosphorylase kinase;
  3. lack of protein kinase;
  4. with no AMP (adenosine monophosphate);
  5. with insufficient activity of hepatic adenylcyclae;
  6. with the absence of glucagon.

Symptoms of Type VI Glycogenosis (Herce’s Disease, Hepatophosphorylase Insufficiency)

Type VI glycogenosis usually manifests itself in the first year of life.

A significant increase in the liver as a result of glycogen infiltration of hepatocytes, growth retardation, a doll face, hyperlipemia, hyperglycemia after intravenous administration of galactose, and an increased glycogen content in red blood cells are characteristic.

Diagnosis of Type VI Glycogenosis (Herce’s Disease, Hepatophosphorylase Insufficiency)

To confirm the diagnosis of glycogenosis and establish its type in the hospital, a biopsy of the liver, muscles (sometimes skin) is performed, followed by histochemical examination; in this case, the glycogen content in the tissues and the activity of the enzymes involved in its metabolism are determined. In case of type II glycogenosis, the activity of acidic α-1,4-glucosidase in the blood cells as well as in the fibroblast cell culture of the patient’s skin and muscles is also determined. Type II glycogenosis can be diagnosed prenatally by biochemical examination of cells of desquamating epithelium of the fetal skin located in the amniotic fluid obtained by amniocentesis.

Differential diagnosis in newborns is carried out with syphilis, toxoplasmosis, cytomegalovirus infection, liver diseases, at an older age – with Gaucher disease, Nimann-Peak disease, myatonia, xanthomatosis. Neuromuscular disorders can mimic progressive muscular dystrophy, amyotrophy – Sharko-Marie-Tooth neural amyotrophy and Verdnig-Hoffmann spinal amyotrophy (with a generalized form of type II glycogenosis); crucial in the diagnosis are relevant biochemical, electrophysiological and morphological studies of muscles.

Treatment of Type VI Glycogenosis (Herce’s Disease, Hepatophosphorylase Insufficiency)

The treatment is aimed at combating metabolic disorders, including with acidosis. In some cases, the use of glucagon, anabolic hormones and glucocorticoids is effective. Frequent meals high in easily digestible carbohydrates are essential for hypoglycemia. With muscle forms of glycogenosis, improvement is observed when following a diet with a high protein content, the appointment of fructose (inside 50-100 g per day), multivitamins, ATP. Attempts are being made to administer to the patient the missing enzymes.

Patients with glycogenosis are subject to clinical observation by a doctor of the medical-genetic center and a pediatrician (therapist) of the clinic.

Prevention of Type VI Glycogenosis (Herce’s Disease, Hepatophosphorylase Insufficiency)

Prevention is not developed. To prevent the birth of a child with glycogenosis in families where there were similar patients, genetic counseling is carried out.