Spinal Muscular Atrophy (SMA)

Spinal Muscular Atrophy (or SMA) is a genetic disorder that affects the nerve cells in the spinal cord. As a disease of the entire body, SMA affects not only muscles but also many other organs.

SMA is caused by a mutation of the survival motor neuron-1 (SMN1) gene, which leads to a deficiency of SMN protein. The SMN protein is found throughout the body and plays a vital role in muscle function.

Having low levels of functional SMN protein leads to progressive weakening and wastage of nerve cells, which control muscle movement, leading to the loss of physical strength and the ability to walk, eat or breathe.

Typically diagnosed in childhood, it is the leading genetic cause of death in infants.

SMA is caused by a mutation of the survival motor neuron-1 (SMN1) gene, which leads to a deficiency of SMN protein.

The body has two very similar genes that make SMN protein:

Having low levels of functional SMN protein leads to progressive weakening and wastage of nerve cells, which control muscle movement.

1 in 45 people is a carrier. When two people carrying the affected gene generate a child:

• 25% risk of producing a child with SMA

• 50% chance that the child is an asymptomatic carrier

• 25% chance that the child will not be affected

A carrier is someone who does not have SMA, having a "normal" copy of the SMN1 gene and a copy of the SMN1 gene with the mutation. Carriers are usually unaware that they have the mutated gene.

Early Detection Checklist

In the treatment of Spinal Muscular Atrophy (SMA), early diagnosis is critical. If you notice any of the following signs in your child, please consult a specialist immediately without delay:

• Hypotonia (“Floppy Baby” Syndrome): The child struggles to hold their head up even after 3 months of birth, or the body feels unnaturally soft or limp.

• Frog-Leg Position: When lying flat on their back, the baby’s legs flop completely open at the knees, resting flat against the bed like a frog’s legs.

• Loss of Physical Milestones: Gradually losing the capability to sit independently after having learned to sit on their own.

• Weak Lungs: Weak lung muscles are forcing your baby to take shallow breaths. Instead of their chest expanding, their belly rises and falls heavily as they struggle to draw in air.

Which Specialist Should to Consult First?

Before running any medical tests, it is essential to consult an experienced Pediatric Neurologist or a Neuromedicine Specialist to receive a proper evaluation and an official referral.

There are 3 main types of SMA, based on the age at which symptoms initially appear.

Type 1

It develops in infants under 6 months of age and according to the natural history of the disease, few children survive beyond 2 years of age.

• Infants who are typically hypotonic due to severe muscle weakness, struggle to control their head or lift their arms and legs

• These infants also have a lot of difficulty breathing normally.

• Infants who will never be able to sit up or roll without help

Type 2

It develops in children between 7-18 months of age, with muscle weakness. Life expectancy may also be affected.

• Children with SMA Type 2 will never be able to walk

• As muscles weaken, some children develop a curvature in the spine called scoliosis

• Many patients develop breathing problems, as well as swallowing problems

• Many achieve the ability to sit, but this ability is lost over time

Type 3

It develops after 18 months of age and may not be evident until late childhood/adolescence.

• The patient is affected with muscle weakness that will worsen over time

• Many children with SMA type 3 will learn to walk, but this ability will be lost as they age into adolescence.

• Life expectancy is not usually affected

• Legs become weaker than arms

What Diagnostic Tests Are Used for SMA?

To reach a definitive and accurate diagnosis for SMA, doctors rely on the following medical evaluations:

• Genetic Testing (MLPA / PCR Test): The absolute gold standard for diagnosing SMA. This blood test confirms mutations or deletions in the SMN1 gene and determines the exact copy number of the SMN2 gene.

• Electromyography (EMG) & Nerve Conduction Studies (NCS): These tests are done to determine whether muscle weakness is neurological and to measure the sensitivity of motor neurons. 

• Creatine Kinase (CK) Test: A simple blood test that checks for muscle damage by measuring CK protein levels. 

• Muscle Biopsy: Since genetic testing is currently easily available, this is not done very much; however, in rare cases, it may be needed to differentiate other neuromuscular disorders. 

Why Is Genetic Testing Vital for SMA?

A genetic blood test is the only scientifically definitive path to confirming SMA:

• Confirms SMN1 Gene Deletion: It is the only reliable method to verify the absence or mutation of the SMN1 gene in the body.

• Identifies the SMA Type & Informs Treatment: Counting SMN2 gene copies helps pinpoint the exact type of SMA (Type 1, 2, or 3), telling doctors how to act immediately. 

• Prevents Permanent Muscle Damage: Early diagnosis before permanent symptom onset enables timely treatment, preventing the destruction of vital nerve cells and motor neurons. 

Where Genetic Test is available in Bangladesh?

In Bangladesh, reliable and official genetic testing for SMA is available exclusively at the National Institute of Laboratory Medicine and Referral Center (NILMRC).

Multidisciplinary Care Ecosystem

To improve the quality of life of SMA warriors and ensure overall well-being, integrated care (Multidisciplinary Care) across 6 specialized fields is essential:

1. Neurology: A neurologist oversees core treatments, protects remaining motor neurons, and tracks overall progress.

2. Pulmonology: A chest specialist focuses on keeping lungs strong, clearing airways, and setting up breathing support if needed.

3. Orthopedics: A specialist to manage joint health, prevent scoliosis (curving of the spine), and keep the body aligned comfortably.

4. Physiotherapy: A physiotherapist works through targeted exercises to preserve muscle movement and functional strength for as long as possible.

5. Occupational Therapy: Helps children learn to use adaptive tools so they can do everyday tasks and gain independence.

6. Speech & Nutrition Therapy: Helps solve swallowing difficulties (dysphagia), improves speech clarity, and ensures your child gets the daily nutrition they need to thrive.

Unsung Superpowers: Sharp Minds & Bright Spirits

While SMA weakens physical muscles, it leaves a child’s cognitive development, memory, and intellectual potential completely untouched. Medical research shows that children living with SMA often possess exceptional mental sharpness, remarkable problem-solving abilities, and vibrant imaginations.

The Unseen Reality: The Caregiver’s Crisis

Behind every child fighting a rare disease is a parent fighting right beside them. But the world rarely sees how heavy that weight really is: 

• Constant 24/7 Burnout: Monitoring a child’s breathing, posture, and comfort every minute of the day leaves caregivers running on physical and emotional emptiness.

• Financial & Professional Sacrifices: The overwhelming costs of lifelong care, therapies, and round-the-clock monitoring force many parents to pause or permanently abandon their careers.

• Social Isolation: A lack of public awareness around rare diseases often leaves these families feeling deeply isolated, misunderstood, and emotionally overwhelmed.

Debunking Common Myths

Myth 1: "SMA is contagious? It can spread from one child to another"

Fact: Not at all. SMA is entirely genetic. It cannot be passed from person to person. Children with SMA can safely play, learn, hug, and go to school alongside anyone else. 

Myth 2: "Children with SMA can not go to school or hold a job"

Fact: Yes, absolutely. Despite physical limitations, the merit and mental capability of individuals affected by SMA remain completely normal. Given the right adaptive technology, motorized wheelchairs, and an inclusive community, individuals with SMA thrive. They grow up to become lawyers, engineers, artists, and top university scholars.

Although SMA is mainly diagnosed in childhood, it can affect people at any age. However, the earlier symptoms appear, the more severe the disease.

Ongoing research is exploring how other cells and organs, including the vascular system and heart may also be affected by reduced levels of functional SMN protein.