Spinal Muscular Atrophy Types
Spinal muscular atrophy is associated with a wide variety of impairments. The neuromuscular disorder is caused by mutations in the SMN1 gene. As the fetus experiences respiratory difficulties from the onset of pregnancy, the disorder’s symptoms begin to manifest. Some individuals with SMA experience a mild degree of muscle weakness. The studies indicate that the classification of SMA into four prevalent types depends more on reaching the highest motor mild stone. The lesser muscles in the human body become progressively weaker and smaller over time. SMA type 1 is the most severe variant of spinal muscular atrophy. It is also known as SMA type 0. SMA type 1 is fatal, uncommon, and associated with severe symptoms. Listed below are the most prevalent types of spinal muscular atrophy;
Type I SMA (Werding-Hoffmann disease).
Infants typically exhibit this form of SMA before the age of six months. Even during gestation, there is a decrease in movement, and as a result, infants are born with breathing difficulties and spine contractures. In the most severe cases of type 1 SMN, infant mortality is possible within the first year of life. Treatment is essential for children born with type 1 SMN. Tongue fasciculations, lack of tendon reflexes, swallowing difficulties, feeding difficulties, impaired respiration, diminished limb movements, and hypotonia (reduced muscle tone) are common symptoms of SMN type 1. As they grew older, infants born with SMA type 1 also developed spinal curvature or other skeletal muscle abnormalities. If a child is not treated, he or she will never be able to squat or stand. Prior to the age of 12 years, the majority of type 1 SMA patients perish due to respiratory system failure. As medicine advances, there are no disease-modifying remedies available, increasing the life expectancy of SMA type 1 patients. Moreover, children with SMA type 1 can develop higher motor skills, such as walking and seating, with the help of proactive methods such as gene therapy.
SMA type 2 (form intermediate)
Children with SMA type 2 begin to exhibit symptoms between the ages of 6 and 12 months; they are unable to walk or stand unassisted but can recline independently. Some children may lose the ability to sit independently for extended periods of time without treatment. There are instances of respiratory issues, such as hypoventilation, which result in sleep disturbances. In the absence of treatment, the disease progression of each type 2 SMA patient is variable. There is a decline in life expectancy, but the majority of children reach young adulthood. The motor outcomes of children with type 2 SMA can improve with the application of proactive clinical care.
The Type 3 form of SMA (Kugelberg-Welendr disease)
After the age of 18 months, the symptoms of SMA type 3 begin to manifest in infants. The children begin to walk independently, but they struggle with sprinting, walking, rising from a chair, and stair climbing. The SMA type 3 affects the proximal muscles prevalent near the body’s core significantly closer to the legs the most. Patients with SMA type 3 suffer predominantly from intermittent hand tremors, indicating impaired signal transduction in the nervous system. There are additional complications associated with SMA type 3 in the absence of treatment. Patients with SMA type 3 may develop complications such as chronic shortening of tendons or muscles surrounding the joints, i.e., joint contracture and spinal cord contracture. Patients cannot readily move their joints, primarily due to decreased muscle tone and weakness. Patients with SMA type 3 are also more likely to develop respiratory issues later in life. Patients can live a normal lifespan if they receive continuous proactive clinical care. If the patient searches out disease-modifying treatments, developmental milestones such as fine and gross motor skills can be reached on time.
SMA category 4
After 21 years, patients with SMA type 4 begin to experience modest to moderate symptoms. Typically, the most prevalent symptoms are proximal muscle weakness and muscle tone loss. SMA type 4 typically affects adults, who are able to manage the disease’s symptoms by extending or utilizing assistive devices.
Other variants of SMA
There are some uncommon and uncommon forms of SMA, such as:
Distal spinal muscular atrophy (DSMA) is a degenerative condition that affects the distal muscles of the spine.
This form of spinal muscular atrophy affects the feet, hands, lower legs, and lower limbs significantly.
SMARD refers to spinal muscular atrophy with respiratory distress.
SMARD is a form of spinal muscular atrophy that manifests in neonates during their first year of life and may result in fatal respiratory complications.
SBMA refers to Kennedy’s disease, or spinobulbar muscular atrophy.
SBMA is an uncommon form of spinal muscular atrophy that affects only males and manifests itself during middle adulthood. The patient’s life expectancy is unaffected by this form of spinal muscular atrophy.
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