Hers disease is assigned to the group of glycogen storage diseases and represents a disease that is characterized in most cases by a deficiency of a specific enzyme. This enzyme is the so-called alpha-glucan phosphorylase enzyme, which is found particularly in the liver.
What is Hers disease?
Hers disease is a metabolic disorder in which glycogen storage is impaired. The disease is inherited in an autosomal recessive or X-linked manner. In German, it is often referred to as Hers disease with the presence of the so-called glycogenosis type VI. A pathological deficiency of phosphorylase in the liver leads to the fact that no sufficient degradation of the substance glycogen can take place. As a result, the glycogen remains in the liver and cannot be made available to the body as an energy substance. Apart from the liver, no other organs are affected by the phosphorylase deficiency in Hers disease in the vast majority of cases.
Causes
Several potential causes exist for Hers disease. Generally, they are enzyme defects in the phosphorylase-kinase system in the liver as well as in the muscles that are congenital. Known causes are an X-linked defect of the so-called phosphorylase-b kinase of the liver, furthermore a defect in liver phosphorylase as well as the combination of the failure of phosphorylase-b kinase in the musculature and the liver. With regard to liver phosphorylase, a link to mutations of a specific gene, the PYGL gene, has been established. With regard to the combined defect of muscle and liver phosphorylase, the PHKB gene has been identified.
Symptoms, complaints, and signs
In most cases, the symptoms of Hers disease appear in childhood and during the period of puberty. The disease is usually characterized by a relatively mild course. The typical leading symptoms of Hers disease are abnormal enlargement of the liver (medical term hepatomegaly) and growth retardation. In addition, mild to moderate hypoglycemia may occur, which, however, recedes with increasing age. Hepatomegaly also diminishes in many cases with increasing age of the affected person and may also regress completely. In some de novo mutations, residual enzyme activity has been demonstrated, accompanied by both mild ketosis and slightly elevated levels of cholesterol, triglycerides, and transaminases. With respect to the X-linked defect in liver phosphorylase kinase, associations with physical disease, such as osteoporosis, cirrhosis, neurologic disease, truncal adiposity, or elevated lactate levels, have also been reported less frequently.
Diagnosis and disease progression
Hers disease can only be diagnosed with certainty by specialist examination and laboratory analysis. Various options exist for making a definite diagnosis of Hers disease, and their use is weighed with respect to the individual case. In many cases, a reduced enzyme activity of the liver (medical term phosphorylase) serves as evidence. Similarly, decreased enzyme activity in both leukocytes and erythrocytes may serve as possible evidence of Hers disease. In addition, decreased levels of glycose and lactate in conjunction with increased levels of transaminases also indicate the presence of Hers disease. In general, the enzyme defect can be detected in the liver as well as in lymphocytes. In addition, molecular genetic detection of a mutation of specific genes in combination with clinical findings represents a further diagnostic possibility of Hers disease. In addition, a liver biopsy may be considered as an instrumental option for the diagnosis of Hers disease.
Complications
Due to Hers disease, children in particular already suffer from various symptoms and complaints. In most cases, disturbances of growth and child development occur. It is not uncommon, therefore, for those affected to be restricted in their daily lives and also dependent on the help of other people. The patient’s quality of life is significantly reduced by Hers disease. Furthermore, mental retardation may also occur, which can lead to learning difficulties. Children can thus become victims of teasing or bullying and develop psychological complaints or depression as a result.Likewise, the disease has a very negative effect on the liver. A causal treatment of Hers disease is not possible. Those affected are therefore dependent on various therapies designed to limit the symptoms. It is not uncommon, however, for the disorders to regress on their own at an advanced age. As a rule, treatment is carried out with the help of stem cells. Immunosuppressants can also limit Hers disease. Whether this results in a reduction in life expectancy generally cannot be predicted.
When should you see a doctor?
The first symptoms of Hers disease appear in childhood through puberty. Growth disturbances or swelling on the body are particularly noticeable. If a significantly decreased body size within the growth process can be perceived in direct comparison to children of the same age, the indications should be discussed with a physician. If there is swelling in the upper body at the level of the liver, a doctor should also be consulted. It must be examined and clarified whether there is an enlargement of the organ. If general dysfunctions occur, if there are abnormalities or changes in the appearance of the skin, or if the drive is reduced, a doctor is needed. If there is pallor or yellowish discoloration of the skin, a visit to the doctor should be made. An inner restlessness, increased irritability as well as disturbances in concentration indicate health impairments that need to be examined and treated. Attacks with ravenous appetite and severe fatigue or exhaustion are further signs of an existing irregularity. If the symptoms persist for several days or weeks, a doctor must be consulted. If behavioral abnormalities occur, emotional as well as mental problems occur or a strong withdrawal behavior is observed, there is cause for concern. A visit to the doctor is necessary so that the cause can be clarified. A decrease in usual performance should also be presented to a doctor.
Treatment and therapy
Therapy of Hers disease with glycogenosis type VI can be purely symptomatic in the vast majority of affected patients, and symptoms should be avoided. In this context, the main goal of treatment is simply to prevent hypoglycemic episodes. In order to carry out this preventive therapy, there must be an overall good prognosis of Hers disease for the individual case. On the other hand, in more complicated cases, compensation of existing metabolic disorders must take place and dysfunctions of organs must be compensated. In addition, concomitant nutritional therapy should also be considered. The diet should be characterized by carbohydrate-rich and small meals. The use of immunosuppressive drugs can be considered as a drug therapy. Hers disease can also be treated surgically by transplantation of stem cells. However, in numerous cases, no therapy of Hers disease is required. However, the disease must be monitored by a physician in the form of regular examinations. In case of a potential worsening of individual symptoms or of the overall condition of the affected patient, appropriate measures for therapy can be initiated immediately. In general, the prognosis for Hers disease can be classified as predominantly good.
Outlook and prognosis
Hers disease usually offers a good prognosis. The disease often regresses during puberty or early adulthood. Until then, the disease offers a comparatively mild course that does not cause major symptoms. Typically, hypotonia, hypoglycemia and growth problems occur. Serious complaints can be avoided by correcting the deficiency symptoms. The prerequisite is usually permanent adherence to a strict diet. In combination with an unhealthy lifestyle or pregnancy, Hers disease can develop into a chronic illness that can result in serious complications. A change in lifestyle or comprehensive treatment of pregnancy improves the prognosis and allows the sufferer to lead a relatively normal life without noticeable limitations. Hers disease often results in psychological complaints that need to be treated. Typical are depressive moods, which also develop due to the hormonal imbalance. The physical limitations are especially problematic, which also cause a limited quality of life.Complications are avoided by a targeted diet and regular check-ups by the physician. The prognosis is made by the specialist, taking into account the symptom picture and the chosen therapy.
Prevention
Because Hers disease is an inherited disorder caused, for example, by gene mutations or certain chromosomal defects, no preventive measures for the disease exist to date. Since Hers disease occurs primarily in childhood and adolescence, it is essential to initiate medical examinations immediately at the first symptoms. The attending physicians can then prescribe preventive and therapeutic measures appropriate to the individual clinical picture. This can have an extremely positive influence on the prognosis for Hers disease.
Follow-up
Follow-up care in the true sense is not available for the genetic metabolic disease Hers disease. There is no causal cure for the disease. The basis of good health despite the condition is an adapted diet as well as follow-up examinations. Accordingly, follow-up examinations result only from examinations to control the success of the therapy. This is sufficient in all milder courses of glycogenosis type VI. As a rule, there are no medical complications resulting in further treatment and follow-up measures. Accordingly, medical aftercare in the narrower sense is not required. The situation is different when organ functions are impaired in more severe cases. The liver in particular can suffer from the metabolic disease, and pathological changes in the tissue and cirrhosis sometimes occur. Accordingly, surgical measures up to and including transplantation are sometimes necessary. This results in the need for medical aftercare to stabilize the patient and guarantee the acceptance of donor material by the body of the affected person. Aftercare examinations are provided. Overall, all affected individuals are well advised to have their metabolism checked at regular intervals. Changing life circumstances and physical changes sometimes make it necessary to adjust the therapy, the success of which should also be monitored by follow-up examinations.
What you can do yourself
Patients suffering from Hers disease must first and foremost adjust their daily habits and, in particular, their diet. The diet must provide long-term energy and stabilize blood glucose levels to stop hypoglycemic episodes. Prolonged periods of fasting must be avoided. Patients should eat frequent smaller meals while maintaining a balanced diet. Poor carbohydrates and simple sugars should only be consumed in limited quantities. Instead, uncooked cornstarch and other slow-digesting foods are a good way to stabilize blood glucose levels. Structured therapy improves well-being and physical and mental performance. Patients should work with their physician and a nutritionist to develop a suitable diet that is tailored to their individual symptoms. This can be accompanied by sports activities. During a hypoglycemic phase, a short walk helps. However, if the symptoms are severe, the doctor should be informed, as serious complications may occur under certain circumstances. In conjunction with drug treatment, Hers disease can be well treated by the self-help measures mentioned above. In severe cases, inpatient treatment in a specialized clinic is necessary.