Myotonic dystrophy type 1 (Curschmann-Steinert syndrome) is an autosomal dominant inherited multisystem disease with the main symptoms of muscle weakness and lens opacification (cataract). One differentiates between two forms of the disease: an innate (congenital) form, in which already the newborn by muscle weakness stands out ("floppy infant") and an adult form, which manifests itself only in the 2nd to 3rd decades of life. The myotonic dystrophy type 1 is not curable and shortens the life expectancy depending on the severity and progression.

What is myotonic dystrophy type 1?

Myotonic dystrophy type 1 is one of the so-called trinucleotide repeat diseases. In the genetic code on the long arm of chromosome 19 there is a trinucleotide from the nucleobases cytosine, thymine and guanine amplified.

While this base triplet repeats 5-35 times in the healthy, affected persons with mild forms of disease find about 50-200, in severe cases even more than 1000 repetitions. The trinucleotide does not directly encode a protein, but does affect the synthesis of other proteins. An enzyme required in skeletal and cardiac musculature, the dystrophy myotonica protein kinase (DMPK), is produced diminished by the genetic defect.

But other proteins are affected, such as the expressed in the lens SIX5 or the insulin receptor. Therefore, myotonic dystrophy type 1 affects many different organ systems. With an incidence of about 1: 20000, myotonic dystrophy type 1 is the most common myotonia and at the same time the most common muscular dystrophy that occurs in adulthood.

In heredity, the number of trinucleotide repeats increases from generation to generation, so that the disease in the offspring always starts earlier and harder. The congenital form is always inherited from the mother. Boys are more frequently affected by myotonic dystrophy type 1 than girls.

causes

In the congenital form, the infant is immediately noticeable after birth due to generalized muscle weakness, a raised upper lip and respiratory insufficiency. Due to respiratory problems, many newborns rely on artificial respiration and 25% -50% die within the first 18 months of life.

Developmental delays and severe mental retardation are to be expected in the longer surviving children. Their life expectancy is about 30-40 years. If the disease does not break out until adulthood, sufferers often first notice muscle weakness in the trunk-less muscles, especially in the legs, neck and face. The facial muscles are atrophied, giving the patients a gaunt look.

Also speech and swallowing disorders result. The muscle weakness is accompanied by a delayed muscle relaxation, so that it is difficult for those affected, for example, to solve a handle again. Other symptoms include cataracts, inner ear deafness, an increased need for sleep, cognitive impairments and reduced glucose tolerance, including diabetes mellitus. The disturbed hormone balance typically causes testicular atrophy and a balding head in men and menstrual disorders in women.

Particularly dangerous are the effects on the heart muscles: Frequently it comes to arrhythmia, sometimes even to cardiac arrest. If the muscle weakness reaches the trunk muscles, respiratory disorders and an increased susceptibility to infection of the lungs are the result. Myotonic dystrophy type 1 is always progressive, but the severity and composition of its symptoms are highly variable. On average, life expectancy in the adult form of myotonic dystrophy type 1 is about 50-60 years.

Symptoms, complaints & signs

The main feature of myotonic dystrophy type 1 is the delayed relaxation of the muscles after a muscle contraction. With this indicator, the disease can be differentiated from other muscular dystrophies. Especially the muscles furthest from the body trunk, such as the face, neck, forearm, hand, lower leg and foot muscles, are affected. Regardless of the muscle symptoms, there are other symptoms.

Thus, cardiac arrhythmias or heart failure often occur. Due to cardiac involvement, narcosis often causes anesthesia incidents. Cataracts and balding in males are often observed. The testosterone level is too low, which often leads to testicular shrinkage. There is an increased risk of developing diabetes.

Speech and swallowing are troublesome for the patient. Furthermore, the patient is constantly tired during the day, which can lead to nocturnal breathing interruptions. Sleep apnea is not always present. Other symptoms may include indigestion, bile or hearing problems. Although it is a hereditary disease, many patients experience symptoms only after the age of 20.

The first sign of disease is often diagnosed with cataracts. However, there is also a form of the disease that already exists from birth. This congenital form of muscle myotonia is characterized by a particularly severe course of life-threatening respiratory insufficiency as well as mental and physical developmental disorders.

Diagnosis & History

Suspected myotonic dystrophy type 1 molecular genetic methods are used to diagnose the disease beyond doubt. These help to rule out differential diagnoses with similar symptoms, eg myotonic dystrophy type 2. The diagnosis can be supported by electromyographic examinations (EMG). In those affected, typical patterns of spontaneous activity are found particularly in the trunk-distant muscles. It is also important to have a thorough family history, also to continue to advise the family.

complications

In this disease sufferers mainly suffer from a strong muscle weakness and symptoms that occur in the eyes. It causes a cataract and clouding of the lens, so that the eyesight of the affected significantly worsened. Similarly, in the worst case, it can also lead to complete blindness.

The quality of life is significantly reduced. Especially young people can develop psychological complaints or depression in cases of sudden vision problems or blindness. Furthermore, heart problems can also occur, so that the patient can die from a sudden cardiac death. Not infrequently, those affected suffer from diabetes.

Muscle weakness significantly limits the daily lives of those affected, so that in some cases they depend on the help of other people. Certain activities or sports can not be carried out without further ado. Children are significantly reduced in their development due to the disease, which can lead to complications in adulthood. It is not possible to treat this disease causally.

However, many complaints can be reduced and alleviated, making everyday life bearable for those affected. As a rule, no particular complications occur and the life expectancy of the patient is not limited by the disease.

When should you go to the doctor?

The need for a doctor's visit is given as soon as the person experiences impairments in coping with his or her everyday life. A weakness of muscle strength, a decrease in physical performance and a loss of tissue are signs of a health disorder. If habitual sporting activities can only be exercised to a limited extent or not at all, the observations should be discussed with a doctor. Various investigations must be initiated in order to clarify the cause and prepare a treatment plan.

Delaying voluntary muscle tension and decreased vision are worrisome. If it comes to blurred vision or cloudiness of the lens, a visit to a doctor is advisable. An irregularity of the natural gripping function is a warning signal of the body, which requires action. An increased risk of accidents and falling must be discussed with a doctor so that countermeasures can be taken. Disorders of the heart rhythm, tachycardia or sleep interruptions should be examined by a doctor.

If there are concentration or attention deficits, or if reduced mental performance is noted due to impairments, a doctor's visit is required. If men suffer from diminished sexual desire or if their forehead baldness develops, a doctor should be consulted. If it comes in addition to emotional or mental stress states, threaten the person affected sequelae. You must be timely prevented.

Treatment & Therapy

A causal treatment of myotonic dystrophy type 1 is not possible. Therapy focuses on alleviating the symptoms, such as surgical treatment of the cataract, drug adjustment in cardiac arrhythmias or technical respiratory support. Physiotherapeutic promotion may delay the progression of myotonic dystrophy type 1.

Outlook & Forecast

The prospects for diagnosed myotonic dystrophy type 1 are poor. Both life expectancy and quality of life suffer. Most patients do not even reach the age of 60 years. Many of them die from heart failure or succumb to infections. Therapeutic measures can often alleviate the symptoms of the disease only marginally. The genetic defect itself is not curable according to previous scientific status. Many sufferers show signs of myotonic dystrophy type 1 even before the age of 20. Others only appear at an advanced age at the doctor. Within families there is an increased risk that the disease will be inherited.

Suffering is on the rise because myotonic dystrophy type 1 is inexorably progressing over the years. Affected individuals find it increasingly difficult to cope with their everyday lives because of muscle weakness. They depend on help. The musculoskeletal system comes to a halt. A learned profession can not be pursued after some time. The therapeutic approaches medication and physiotherapy lose more and more effect over time. Not infrequently, the physical decline of myotonic dystrophy type 1 is accompanied by mental problems.

prevention

Since type 1 myotonic dystrophy is an inherited genetic defect, prevention is not possible.

aftercare

Myotonic dystrophy type 1 is hereditary. A cure is not possible according to the current state of research. Life expectancy is reduced by the disease by about 50 years. Follow-up is advisable to slow the progression of dystrophy. Further goals of a follow-up companion are the symptom relief and the preservation of the quality of life.

At follow-up, the compatibility of drugs is also controlled if administered to the patient. The aftercare service primarily refers to physical complaints. The mobility of the limbs should be maintained as long as possible by appropriate exercises. Accompanying psychotherapy may also be appropriate or even necessary.

An inadequate quality of life due to dystrophy can affect the patient mentally. The danger of depression is very high. In psychotherapy, it is possible to talk about negative feelings. At an advanced stage, a wheelchair may be required. During the aftercare the sick person learns the everyday handling of the device.

Myotonic dystrophy also affects cardiac function. A pacemaker counteracts the process. The follow-up treatment is performed by a cardiologist. He monitors the healing process after the operation. The control stops when the healing is as expected.

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