Spinal Muscular Atrophy: Is Treatment Available?

Spinal muscular atrophy (SMA) is an inherited genetic disorder with an incidence of 1 in 10,000 people. It leads to progressive muscle weakness and loss of movements sometimes complicated by breathing dysfunction, deformities and recurrent chest infections. It primarily affects the motor neurons in the spinal cord, which control voluntary muscle movements. SMA is typically caused by mutations in the SMN1 gene, essential for motor neuron survival. Both parents usually carry the defective gene.

There are 3 subtypes of SMA in children based on the severity and age of presentation:

• Type 1 is the most severe form with a life expectancy of 1-2 years. 
• Type 2 SMA children suffer from disabilities and recurrent infections with a variable survival. 
• Type 3 SMA usually presents with walking difficulties and have normal survival.

Children with SMA experience varying degrees of muscle weakness, impacting mobility, swallowing and breathing. Symptoms range from mild walking difficulty to complete paralysis and breathing and swallowing dysfunction. Various bony deformities, scoliosis and dislocations can complicate their progress.

Is any treatment available?
Until a few years back, no definitive treatment was available and supportive care was all that was available. In recent years, three FDA approved treatments have become available for this otherwise untreatable disease.

Nusinersen injection: An intrathecal antisense oligonucleotide that increases SMN protein levels by activating the SMN2 gene and is given lifelong.

Onasemnogene abeparvovec (Zolgensma): A single dose intravenous gene replacement therapy that replaces the functional SMN1 gene.

Risdiplam: An oral small molecule that boosts SMN protein production by stimulating SMN2 gene and is again given for life.

Early treatment is essential for best outcomes as the motor neurons in spinal muscular atrophy are quickly degenerating. Despite giving these medications, a multidisciplinary care in cornerstone in the successful management of SMA children. A multidisciplinary team comprising of a paediatric neurologist, pulmonologist, physiotherapist, speech therapist, dietitian, orthopaedic and spine surgeon is a must to address the diverse needs of these children and improving the quality of life and functional independence in these young warriors.

P. D. Hinduja Hospital aims to bring such medical expertise  with our SMA Clinic. For more guidance and appointment, you may call on 022 24447216.

Genetic counselling is of utmost value, as this disorder can recur in subsequent pregnancies and antenatal diagnosis is possible.