Understanding Spinal Muscular Atrophy: Causes, Symptoms, Treatment, and Prevention

Introduction: Shedding Light on Spinal Muscular Atrophy

Spinal muscular atrophy (SMA) is a rare genetic disorder that impacts lives worldwide, affecting motor neurons and muscle function. As of September 1, 2025, 04:59 PM IST, awareness about SMA is more critical than ever. This article explores the causes, symptoms, treatments, and prevention strategies to empower those affected and their families with knowledge.

What Causes Spinal Muscular Atrophy?

SMA is primarily caused by mutations in the SMN1 gene, located on chromosome 5. This gene is responsible for producing the survival motor neuron (SMN) protein, essential for motor neuron health. When both copies of the SMN1 gene are defective—typically inherited from carrier parents—the body produces insufficient SMN protein, leading to motor neuron degeneration. Approximately 1 in 6,000 to 10,000 babies are born with SMA, with a carrier frequency of 1 in 40 to 1 in 60. Rarely, spontaneous mutations can occur, but most cases are autosomal recessive.

Recognizing the Symptoms of SMA

Symptoms of SMA vary by type, depending on age of onset and severity. The condition is classified into four main types:

• Type 1 (Infantile SMA): The most severe, appearing before 6 months. Babies may struggle with breathing, swallowing, and sitting unsupported, with a life expectancy often under 2 years without intervention.

• Type 2: Emerges between 6 and 18 months. Children can sit but cannot walk, with varying life expectancy based on care.

• Type 3 (Juvenile SMA): Begins after 18 months, allowing independent walking initially, though mobility declines over time.

• Type 4 (Adult SMA): Mildest, starting in adulthood, with slow progression and normal life expectancy.

Common signs include muscle weakness, poor muscle tone, difficulty moving, and, in severe cases, respiratory challenges. Early recognition is key to improving outcomes.

Available Treatments for SMA

While there’s no cure, treatments have transformed SMA management since 2016. Options include:

• Nusinersen (Spinraza): An injection that increases SMN protein production, approved for all ages, improving motor function.

• Onasemnogene Abeparvovec (Zolgensma): A one-time gene therapy for children under 2, replacing the defective SMN1 gene.

• Risdiplam (Evrysdi): An oral medication boosting SMN protein, suitable for those 2 months and older.

• Supportive Care: Physical therapy, respiratory support, and nutritional guidance help manage symptoms and improve quality of life.

Early intervention, often aided by newborn screening now standard in many regions, is crucial. Consult a neurologist to explore personalized treatment plans.

Prevention Strategies for SMA

Preventing SMA involves genetic awareness since it’s inherited. Key steps include:

• Carrier Testing: Couples with a family history of SMA can undergo genetic testing to assess risk (1 in 4 chance if both are carriers).

• Preimplantation Genetic Diagnosis (PGD): During IVF, this identifies unaffected embryos, reducing transmission risk.

• Prenatal Testing: Amniocentesis or chorionic villus sampling (CVS) can detect SMA in pregnancy.

• Education: Raising awareness about SMA genetics helps families plan and seek early support.

While these methods can’t prevent all cases, they empower informed decisions.

Living with SMA: A Community Perspective

Connecting with others is vital. Organizations like the Muscular Dystrophy Association (mda.org) and Cure SMA (curesma.org) offer resources and support groups. Sharing experiences fosters resilience, especially for families navigating SMA’s challenges.

Why Awareness Matters

As we mark SMA Awareness Month in August 2025 in India, let’s prioritize education and support. Early detection and community strength are transforming lives—your knowledge can make a difference.