Spinal muscular atrophy (SMA) is a hereditary disorder causing muscle weakness due to nerve cell degeneration in the spinal cord. Symptoms vary across four types, from infancy to adulthood, impacting mobility and respiratory health. Understanding its causes and signs can aid early diagnosis and management.

Ultimate Overview of Spinal Muscular Atrophy (SMA)

Spinal muscular atrophy (SMA) is a genetic condition that targets the nerve cells controlling voluntary muscles. These vital nerves are mainly located in the spinal cord, which the disease name references. SMA leads to weakening of muscles because the damaged nerves fail to send signals properly, causing muscle wasting or atrophy. It is categorized as a motor neuron disorder due to the gradual loss of these nerve cells, resulting in muscle deterioration and mobility issues.

Causes of Spinal Muscular Atrophy

SMA is inherited genetically from parents.

Children inherit two defective copies of a gene, one from each parent.

This gene mutation hampers the production of SMN protein, vital for motor neuron health.

Carriers possess only one faulty gene and can transmit it to offspring.

Common Signs and Symptoms

SMA symptoms differ based on its type:

Type 1, the most severe form, appears in infancy with quick muscle weakening, head control issues, and breathing difficulties. Most affected children do not survive beyond age two.

Type 2, or infantile SMA, affects children between 6-18 months, mainly weakening leg muscles. Children may sit or stand with support but often face mobility challenges.

Type 3, juvenile SMA, occurs in children and teens aged 2-17, who can walk and sit independently but may struggle with running, climbing, or standing, with wheelchairs sometimes required later.

Type 4 presents in adulthood with symptoms such as muscle weakness, twitching, and breathing problems.