The various types of muscular dystrophy are distinguished from each other by the anatomical area where the first symptoms appear and the severity of the related disorders.
Below is a brief description of the best known types of muscular dystrophy.
Duchenne Muscular Dystrophy
Being a hereditary disease linked to sex chromosome X, Duchenne muscular dystrophy ( DMD ) mainly affects men and only rarely women.
The mutated gene that causes the condition is the one that produces a protein called dystrophin in a normal individual.
The first muscles to manifest the symptoms of Duchenne muscular dystrophy are the voluntary muscles of the legs and arms, which depart from the trunk (therefore quadriceps, ileopsoas, gluteus etc. with regard to the lower limbs; deltoid, pectoral, subscapular, etc. as far as concerns the upper limbs).
The sick, from the 1st-3rd year of life, accuse:
- Difficulty walking, running and jumping
- Difficulty standing up
- Difficulty learning to speak. Indeed, they begin to do so much later than their normal peers.
- Difficulty climbing the stairs without the help of a support
- Cognitive and behavioral deficit (NB: applies only to some subjects)
Between the ages of 8 and 14, the sick need the wheelchair, because they can no longer walk; furthermore, they begin to suffer from scoliosis .
At the age of about 15, therefore, the first heart problems appear ( dilated cardiomyopathy ). Subsequently, at the age of 20, the first respiratory deficits arise, which are due to a functional reduction of the intercostal muscles and the diaphragm.
As soon as the heart and lungs begin to be affected, patients are in danger of death. Death, in fact, generally occurs due to cardio-respiratory problems, at about 27-30 years.
Summary of the main features of Duchenne muscular dystrophy
Type of inheritance: hereditary disease linked to the sex chromosome X.
Gene involved: DMD. It is the gene that produces the dystrophin protein.
Most affected sex: male.
When the first symptoms arise: early, around the 1st-3rd year of life.
First muscles involved: the voluntary muscles of arms and legs that depart from the trunk.
Life expectancy: death occurs around 27-30 years.
Quality of life: already from the age of 8 the patient may need a wheelchair.
Main causes of death: cardio-respiratory failure.
Myotonic dystrophy
Muscular weakening, caused by myotonic dystrophy ( DM ), usually starts from the muscles of the face, jaw and neck (therefore, unlike Duchenne muscular dystrophy, from small muscles).
The symptoms, which can appear at any age, consist of:
- Prolonged contractions and muscle contractions ( myotonia )
- Cataract
- Excessive sleepiness ( hypersomnia )
- Difficulty in swallowing ( dysphagia )
- In children, behavioral and learning problems
- Heart rhythm irregularities ( arrhythmias )
The evolution of the disease is not the same for every patient: some deteriorate very slowly, others suddenly.
Also disability and life expectancy change from sick to sick: in fact, someone manifests serious cardio-respiratory problems and dies within a few years of the onset of symptoms; someone else, however, lives as much as a normal person.
The three main causes of death are: pneumonia, respiratory failure and / or heart failure.
According to some studies, the passage of myotonic dystrophy from generation to generation is characterized by a gradual worsening of the disease. In other words, the children of sick people tend to have a worse clinical picture than their parents.
Summary of the main features of myotonic dystrophy (DM)
Inheritance: autosomal dominant inherited disease.
Subtypes: two, myotonic dystrophy 1 (DM1) and myotonic dystrophy 2 (DM2)
Genes involved: DPMK, for DM1, and ZNF9, for DM2.
Most affected sex: same frequency between men and women.
When the first symptoms arise: at any age.
First muscles affected: the muscles of the face, jaw and neck.
Life expectancy: variable; some patients die quite early and a few years after the onset of the disease; others, instead, live a normal life.
Quality of life: variable, depending on the severity of the symptoms.
Main causes of death: cardio-respiratory failure and pneumonia.
Facio-scapulo-humeral muscular dystrophy
Lamppoli of the scapolar girdle and ( FSHD ) mainly affects male individuals; the reason for this is, for now, still unclear.
In about 1/3 of patients, symptoms appear in adulthood; in the remaining 2/3, the symptoms begin during childhood and progress very slowly.
Figure: Winged scapulae, sometimes asymmetric, represent a characteristic sign of Facio-Scapulo-Humeral Muscular Dystrophy .
From the site: fshsociety.org
Generally, in childhood, patients report problems to the muscles of the face and, in fact, have difficulty in:
- Keep your eyes closed while they sleep
- To smile
- Close your eyes when they are awake
- Whistle
Only starting from the adolescent / adult age, they begin to feel disturbances even at the level of:
- Shoulder blades (the typical signs are the winged shoulder blades and the oblique shoulders)
- Arms (unable to lift the humerus of the arms)
- Upper back
- Calves
The involvement of the leg muscles occurs only in half of the cases and, according to some statistical data, only 1-2 patients out of 10 need the wheelchair.
It is possible that the disease evolves discontinuously and slowly and that it affects only one side of the body.
Usually, people with facio-scapulohumeral muscular dystrophy live a life of normal duration.
Summary of the main features of facio-scapulo-humeral muscular dystrophy (FSHD)
Type of inheritance: autosomal dominant inherited disease.
Involved gene: DUX4.
Most affected sex: it can affect both sexes, but it is more common in men.
When the first symptoms arise: from childhood.
Affected muscles: voluntary muscles of the face (the absolute first), of the shoulder blades, of the arms, of the upper back and legs (only in some cases).
Life expectancy: normal.
Quality of life: some motor functions are prevented, but only 1-2 patients out of 10 need the wheelchair.
Becker Muscular Dystrophy
Becker muscular dystrophy ( BMD ) is a less severe form of Duchenne muscular dystrophy. The mutated gene, responsible for the disease, is, in fact, the same (the one that codes for dystrophin).
In general, the symptoms first appear during mid-childhood and consist of:
- Problems walking
- Frequent muscle cramps during physical activity
- Great difficulty in doing sport or gymnastics at school
As patients grow and become adults, they increasingly experience difficulty running, walking fast, climbing stairs or lifting objects.
However, unlike the Duchenne muscle syndrome, the wheelchair usually becomes indispensable only from the age of about 40-50 years (NB: this is an average figure, as some patients need it already at 15- 20 years, while others only during old age).
Heart problems (dilated cardiomyopathy) and respiratory problems ( respiratory failure) are likely to occur; however these are not such as to lead to premature death, as is the case with Duchenne muscular dystrophy.
Summary of the main features of Becker muscular dystrophy (BMD)
Type of inheritance: hereditary disease linked to the sex chromosome X.
Gene involved: DMD. It is the gene that produces the dystrophin protein.
Most affected sex: male
When the first symptoms arise: during middle childhood.
First muscles involved: the voluntary muscles of arms and legs that depart from the trunk.
Life expectancy: normal.
Quality of life: patients have problems walking and running, but they generally resort to wheelchairs only around the age of 40-50.
Main causes of death: cardio-respiratory problems are not usually such as to cause premature death of the patient.
Muscular Dystrophies of the Tracks
All the muscular dystrophies that, at the onset of symptoms, cause a weakening of the muscles of the pelvic girdle and of the shoulder girdle belong to the group of muscular dystrophies of the limbs (whose English acronym is LGMD ).
Each variant is also linked to the fact that the first symptoms appear during late childhood or during adolescence and that men and women are affected equally.
The typical symptoms are:
- Muscle weakness in the hips, legs and arms
- Reduction of muscle mass in the girdle, scapular and pelvic level.
- Persistent back pain
- Palpitations and cardiac irregularities (arrhythmias)
In the long run, patients may experience difficulties in lifting objects, running or getting up from very low chairs or shelves.
Summary of the main features of the muscular dystrophy of the limbs (LGMD)
Type of inheritance: variable. Some subtypes are dominant autosomal hereditary diseases, others are autosomal recessive inherited diseases.
Gene involved: different depending on the variant of limb-girdle muscular dystrophy.
Sex more affected: both sexes suffer equally.
When the first symptoms arise: late childhood or even later (late adolescence).
First affected muscles: voluntary muscles of the shoulder girdle and pelvic girdle.
Life expectancy: depends on the variant.
Quality of life: depends on the variant. For some patients, the symptoms are severe; for others, it is mild and only some motor functions are compromised.
Main causes of death: depends on the variant: some may cause serious heart problems.
Oculopharyngeal Muscular Dystrophy
Oculopharyngeal muscular dystrophy is characterized, above all, by a weakening of the ocular muscles (ie of the eyes) and pharyngeal (that is, of the throat).
It appears in adulthood, generally around 50-60 years, and involves the following symptoms:
- Eyelid ptosis (or total or partial lowering of the upper or lower eyelids) and gradual reduction of eye movement. These two disorders can cause a loss of vision or double vision .
- Dysphagia . Because of dysphagia, it can happen that food, saliva or liquids "take" the respiratory airways instead of the esophagus. Thus, bronchial and pulmonary infections can occur.
- Weakening of the muscles located at the level of the shoulders and hips . This occurs at an advanced stage of the disease.
Thanks to an adequate treatment, it is possible to treat the symptoms of the disease even with moderate success; life span is also almost always the same as a healthy person.
Summary of the main features of oculopharyngeal muscular dystrophy
Type of inheritance: autosomal dominant inherited disease.
Gene involved: PABPN1.
Sex more affected: both sexes suffer equally.
When the first symptoms arise: generally around 50-60 years.
First affected muscles: the eye and pharyngeal muscles.
Life expectancy: normal, especially if the patient is treated appropriately.
Quality of life: in a late phase, the disease also affects the muscles of the shoulders and hips; however, treatments are now available that can alleviate symptoms even with moderate success.
Emery-Dreifuss Muscular Dystrophy
Emery-Dreifuss muscular dystrophy is characterized by repeated contractures of the muscles located near the main joints of the body. In particular, the most affected sites are the shoulders, arms, neck, legs and ankles.
With the passage of time, the patient accuses ever greater problems in flexing his neck forward, raising his arms over his head, lifting objects, walking or climbing stairs; once he reaches the most advanced stages of the disease, he is usually confined to the wheelchair and begins to suffer from heart problems. The heart, in fact, tends to progressively lose part of its functions, giving rise to palpitations, cardiac arrhythmias and fainting episodes.
In general, heart disorders are such that implantation of a pacemaker is required in order to regularize the heartbeat.
In most cases, patients die from cardio-respiratory failure around middle age.
Summary of the main features of Emery-Dreifuss muscular dystrophy
Subtypes and type of inheritance: three; a subtype is an autosomal dominant inherited disorder; another is an autosomal recessive inherited disorder; finally, the third is an inherited disease linked to the sex chromosome X.
Genes involved: EMD or LMNA.
Most affected sex: varies depending on the type of inheritance.
When the first symptoms arise: during childhood or adolescence.
First muscles involved: the voluntary muscles located near the joints: shoulders, arms, neck, legs and ankles. It is the cause of recurrent contractions.
Life expectancy: death usually occurs in middle age.
Quality of life: the patient is forced to wheelchair, because he cannot walk. Even the simplest arm movements are difficult.
Main causes of death: cardio-respiratory failure.
Distal Muscular Dystrophies
Distal muscular dystrophies are a group of 8 muscular dystrophies characterized by a weakening of the muscles located at the extremities of the limbs, therefore: hands, forearms, feet and calves.
The following diseases constitute the group of distal muscular dystrophies:
- Welander distal myopathy
- Miyoshi's distal myopathy
- Finnish (or tibial) distal myopathy
- Nonaka distal myopathy
- Distal Gowers-Laing myopathy
- Inherited myositis from type 1 included bodies
- Distal myopathy with weakening of the vocal cords and pharynx muscles
- Zaspopathy (or distal myopathy associated with the ZASP gene)
In general, the progression of distal dystrophies is very slow: the first symptoms, for example, usually appear around the age of 40-50.
The quality of life of patients is in part affected, although it must be remembered that, with certain exceptions, they do not die prematurely.
Summary of the main features of distal muscular dystrophies
Subtypes and type of inheritance: eight; some subtypes are autosomal dominant inherited diseases, others are inherited autosomal recessive diseases.
Genes involved: DYSF and TIA1.
Most affected sex: unknown data.
When the first symptoms arise: during middle age, between 40 and 50 years.
First muscles involved: the voluntary muscles located at the ends of the upper and lower limbs, therefore: hands, forearms, feet and calves.
Life expectancy: in general, life span is not affected.
Quality of life: it is conditioned, as the patient has several motor deficits. Much depends, however, on the ongoing subtype of distal muscular dystrophy.
