Motherhood is undoubtedly one of the sweetest things on earth. Parents nurture their children no matter what the odds are. Their mind will always get troubled even with a small illness in their babies. However, some diseases can wrench their hearts. One such disease is a genetic disorder called ‘Spinal Muscular Atrophy’ (SMA). Severe forms of SMA are life-limiting diseases. The scientific advances in understanding the disease and newer therapies have greatly helped in prolonging the life and improving quality of life of these children.
What is Spinal Muscular Atrophy (SMA)?.
Spinal Muscular Atrophy is a neurological condition caused by a defect in the SMN1 gene. Normally, every person is born with a gene called SMN1 which produces a protein called SMN protein, in many cells in our body. This protein is essential for normal functioning of nerve cells in the spinal cord called the ‘anterior horn cells’. The anterior horn cells control the skeletal muscles essential for all our movements (of limbs, neck, back, breathing and swallowing etc,). However, absence of SMN1 gene causes reduction in the amount of SMN protein produced in anterior horn cells. The reduced quantity of SMN protein causes gradual death of anterior horn cells, and thus progressive weakness of muscles of limbs, trunk and breathing and swallowing muscles. Depending on the age of child and severity of SMA, the speed with which the muscles become weaker varies. There are broadly three types of SMA depending on the age at which weakness starts and severity of weakness, with type 1 being most severe.
SMA Type 1: It is the most severe type of SMA. These children will never achieve independent sitting, and at best, can attain neck holding and rolling over. The symptoms usually manifest by around 3-4 months age. Untreated, they progressively develop breathing difficulty and swallowing difficulty leading death by around 2 years age.
SMA Type 2: These children will attain sitting without support, but, will not be able to walk independently. After few years, they may have worsening of weakness and complications like repeated lung infections, poor weight gain, scoliosis (curvature of spine) etc, which drastically reduces their quality of life with frequent hospitalizations.
SMA Type 3: This is the milder form of SMA. The affected persons can walk independently, but has difficulty walking upstairs, getting up from floor and clumsiness in outdoor activities.
Major Symptoms: The symptoms depend on the age of the child
- Poor movement of legs and arms
- Not being able to sit without support
- Inability to stand upright
- Inability to walk without support
- Limbs feel floppy/loose
Diagnostic Tests
The diagnosis of SMA is suspected based on the symptoms, and can be confirmed using Nerve conduction studies and SMN gene deletion by MLPA, a blood test.
How is SMA treated?
Multidisciplinary Care
For children suffering from SMA, supportive care is the cornerstone of management: It involves specialists from multiple fields of medicine including Pediatric Neurologist, Pulmonologist, Pediatric Orthopedician, Physiotherapist, Pediatric Intensivist, Pediatric Surgeon and Dietitian through coordinated approach. The multidisciplinary care as important (perhaps, more important) than giving medicines. Without good supportive care, taking medicines alone is futile and will not result in much improvement. At the same time, with good coordinated supportive management, these children can avoid repeated lung infections and frequent hospitalizations. There are Parent Support Groups, members of which will support the newly diagnosed patients and their parents and also provide the required information. They offer moral support which can bring a lot of comfort to the families.
Until five years ago, the treatment for this disease didn’t exist. It was mainly the supportive care (Physiotherapy, diet advice and chest care etc.). There are currently three types of medicines available for treatment of children and adults with SMA.
1. Spinraza (Nusinersen)
This was the first disease-modifying treatment approved for treatment of SMA. This is an ‘exon skipping’, with medicine injected into the spine. There is no age limit for the administration of this medicine. It works by increasing the quantity of SMN2 expression, and thus SMN protein quantity. The children should take this medicine once every four months for life. Currently, this medicine is not marketed in India, and need to be imported.
2. Gene therapy (Zolgensma)
Zolgensma is an artificially prepared SMN1 gene, coupled with a innocuous viral vector (AAV9) and administered as a single-dose intravenous infusion. This medicine is approved for use in children under two years of age only. The gene therapy shows its greatest benefit in pre-symptomatic infants i.e. young babies before they manifest the symptoms of SMA (typically, before 6-8 weeks of age). These babies can attain milestones similar to normal children.
3. Risdiplam
Risdiplam is the most recent approved drug (in 2020). It is in the form of powder and the reconstituted solution is given orally, once daily, life-long. The medicine is available in our country from past 1 year. There is no age limit for taking this medicine but children. It also increases the quantity of SMN protein by increasing the expression of SMN2 gene.
Dr Ramesh Konanki, Pediatric Neurologist
Dr Ramesh Konanki, MD (Pediatrics),AIIMS,DM(Paediatric Neurology),AIIMS,
Rainbow Children’s Hospital, Karkhana, Secunderabad
Multidisciplinary team at Rainbow, Secunderabad
At Rainbow children’s hospital, Secunderabad, we have been treating children with SMA for the past 12 years. To provide best care for these children, we have a dedicated team of specialists including Pediatric neurologist, physiotherapist, Orthopedician, Pulmonologist, dietitian and Intensivist, and facilities including a sleep lab. So far, we have treated 5 children with Gene therapy (Zolgensma), and 18 children are receiving Nusinersen (Spinraza), while 5 children are receiving Risdiplam. We have been running a dedicated two-monthly “SMA Clinic” to provide one-stop care for children with SMA.
