Spinal Muscular Atrophy (AME) is a disease genetics recessive autosomal linked to chromosome 5 that has an incidence of 1:6,000 to 1:10,000 births. It is caused by an alteration of the motoneuron survival gene 1 (SMN).1). This modification causes the SMN protein to not be produced properly, leading to alpha motoneurons, located in the spinal cord, to degeneration.
The degeneration of these neurons triggers in the patient weakness, decreased muscle tone and progressive muscle paralysis. The disease mainly affects respiratory, bulbar and paravertebral muscles, causing no problem in the sensory function of patients.
According to age and muscle impairment, the disease can be classified into four types:
- Type I or acute - The disease affects the patient early, before six months of life, leading to death even before reaching two years of age. Usually this type of EBF causes rapid motor and respiratory impairment and, by the first year of age, the child is no longer able to swallow. This is the most serious form of the disease.
- Type II or chronic - Generates symptoms normally after 6 and up to 18 months of life. Life expectancy is around 10 years, according to some authors. Although the impairment is milder than in type I, patients with type II never acquire the ability to walk, in addition to having difficulty swallowing and coughing.
- Type III or juvenile - Symptoms start after 18 months of life. Those who are affected before the age of three are able to walk to approximately 20 years of age, and those who show symptoms after that age walk for a lifetime. The life expectancy of this group is undefined.
- Type IV or adult – The problem arises after 10 years of age according to some authors, while others claim that this type of EBF only starts after 20 years of age. The disease does not cause great motor impairment or problems with swallowing or breathing. The patient therefore has a normal life expectancy. It is the least aggressive type of the disease.
O diagnosis of EBF it is done through the analysis of the clinical picture and tests of molecular analysis and electromyography. As it is a progressive and incurable disease, treatment is based on retaining the rapid progression of the disease and improving the patient's quality of life. The main problems treated are respiratory, nutritional and physiotherapeutic, thus requiring a multidisciplinary team.
Patients with this disease should be aware of the possibility of having children, since this atrophy is genetic. Therefore, it is essential that couples in which at least one has EBF perform the genetic counseling.
By Ma. Vanessa dos Santos
Source: Brazil School - https://brasilescola.uol.com.br/doencas/atrofia-muscular-espinhal.htm