Steinert’s disease: first symptoms, what life expectancy?

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Steinerts disease first symptoms what life expectancy

7,000 to 8,000 French people are affected by Steinert’s disease or Steinert’s myotonia, a rare and hereditary disease that weakens the muscles.

Steinert’s disease, otherwise called “myotonic dystrophy type 1″ (DM1) or “Steinert’s myotonia” is a neuromuscular disease, rare, hereditary and genetictouching one person in 10,000, or around 7,000 in France. It mainly affects the muscles and affects both women and men.

Definition: what is Steinert’s disease?

Steinert’s disease is a neuromuscular, genetic and hereditary disease. “Very disabling in the long term, this condition is called “multi-systemic” because it affects both the muscles (weakening and atrophy of the muscles, called “dystrophy”, lack of muscle relaxation called “myotonia”), but also other organs (cardiorespiratory system, digestive system, nervous system, hormonal system, etc.). ), explains Gérard Rivière, President of the association Friends of the Information Portal on Steinert Disease. It is expressed and evolves very differently from one patient to another and There is currently no treatment for the genetic anomaly. However, some of its symptoms can be managed.”

What are the symptoms of Steinert’s disease?

The disease is mainly characterized by muscular symptoms:

  • Muscle stiffness
  • Significant and increasing fatigue
  • A decrease in muscle volume
  • Difficulty walking, to speak, to hold one’s head, to lift and hold a heavy object.

But the disease can also affect organs other than the muscles, such as:
► The heartwhich leads to heart rhythm disturbances
► The respiratory system, leading to difficulty breathing with coughing and shortness of breath, or even sleep apnea, resulting in poor blood oxygenation and excess carbon dioxide.
► The central nervous systemwith neurological disorders (hypersomnolence: tendency to fall asleep easily, to sleep for a long time), even cognitive disorders
► The hormonal system, patients then present with poor functioning of the sexual glands leading to a reduction in fertility
► The eyeswith the early development of a cataract.
The symptoms can be very different from one person to another, depending in particular on the age of onset, which has led to the disease being classified into several “shapes“.”They range from the most serious form, called “neonatal”, when symptoms are apparent from birth, at so-called “late or asymptomatic” forms, when symptoms appear late or are very mild and inconspicuous“, specifies Gérard Rivière.

What is the cause of Steinert’s disease?

“This disease is said to be “autosomal dominant”, i.e. that it is enough for one of the two parents to be affected (both the mother and the father) so that the risk of transmission to children exists. This risk is one in two (50%) at each birthwhich means that in a sibling from a carrier parent, all the children can be affected, or only a few or none“, explains Gérard Rivière. It is due to a abnormality in the DNA of a gene located on chromosome 19. This gene codes for an enzyme (DMPK, for Dystrophy Myotonin Protein Kinase) which is involved in particular in the functioning of muscles. “The defect, a sort of “bug”, consists of a abnormal repetition of a sequence of 3 “letters” in the DNA of the gene, explains our expert.

A frequent worsening when it is transmitted to the next generation

This repetition, which ranges from 50 to several thousand times, disrupts not only the production of DMPK, but also the synthesis of other proteins necessary for the proper functioning of all the body’s organs. The number of these repetitions generally correlates with the severity of symptoms and the precocity of their occurrence“This tends to increase from one generation to the next if the disease is transmitted.”This last point explains the frequent worsening of the disease during genetic transmission from one generation to the next“, remarks Gérard Rivière. We do not know the cause of the initial mutation in the DNA in the first affected parent in a pedigree. There is no transmission of the disease other than genetic (no contagion between individuals).

The disease is suspected in the presence of suggestive symptoms and/or the existence of disorders in the family history. But it will only really be confirmed following genetic analysis, using a simple blood test. A electromyogram (a test that measures the electrical activity of the muscle) can sometimes be performed.

There is no no treatment at present which makes it possible to cure the genetic origin of this disease (it is necessary to be able to intervene on the DNA or RNA in the nucleus of all the cells of the body). The treatments therefore consist of multidisciplinary symptom management :

  • to slow down stiffness and muscle weakening, physiotherapy sessions are generally prescribed
  • on the cardiac level, regular monitoring is put in place (electrocardiogram, Holter monitoring, etc.). There insertion of a pacemaker may be necessary for preventive purposesto avoid dangerous cardiac dysfunctions (risk of sudden death);
  • on the respiratory level, the measurement of oxygen and carbon dioxide in the blood is regularly measured and, if necessary, nocturnal breathing assistance can be put in place (NIV, non-invasive ventilation);
  • daytime sleepiness can be controlled with medication;
  • when it interferes with vision, the cataract is operated on;
  • psychological support can also be provided to patients

What is the life expectancy in case of Steinert’s disease?

Apart from severe forms of the newborn, life expectancy is practically normal if the symptoms are well managed, including cardiac monitoring.

Thanks to Gérard Rivière, President of the association Friends of the Information Portal on Steinert Disease.


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