SPINAL MUSCULAR ATROPHY (SMA)

SPINAL MUSCULAR ATROPHY

Edited by, JOHN FELIX

Spinal Muscular Atrophy(SMA) is an inherited/genetic disorder causing muscles to become weak. It is a neuromuscular disease whereas the individual may lose the motor neurons(specific type of nerve cell) of the spinal cord. These motor neurons are responsible for the movement of muscles. Without these nerve cells, the muscles fail to receive signals that makes the muscles move.

The term Atrophy means decrease in the size of cells or tissues. The cells become smaller in size due to lack of usgae. SMA is a rare disorder which affects 1 in 10,000 population. This disorder is most common among children. The cost of treatment for SMA is very high.

A patient with SMA inherits two missing or mutated survival motor neuron gene, one from father and the other from mother. This results in decrease in Survival Motor Neuron(SMN) protein

TYPES:

Spinal Muscular Atrophy is of four types namely;

Type I: This condition is the most common form of SMA. This is a severe condition where the muscles weakness may be noticed at birth. They may face swallowing problems and breathing problems due to muscle weakness. Most children may die due to respiratory problems. This condition is also called Werdig-Hoffmann Disease

Type II: This condition usually occurs in children between 6 - 12 months of age. The affected children may face difficulties similar to that of Type 1. This condition is also called Dubowitz disease.

Type III: This condition may occur after early childhood. The affected children may walk unaidedly but may require wheelchair in the later life. They may have the normal life expectancy. This condition is also called Kugelberg-Welander disease.

Type IV: This is a very rare condition which occur at early adulthood. The affected individuals may have mild muscle weakness. They have normal life expectancy.

SYMPTOMS:

Generally people with SMA may have the following symptoms:

• Progressive loss of muscle control

• weak muscles

• In severe cases, people will never Walk or Sit

Zolgensma-Costly medication?

Onasemnogene abeparvovec, sold under the brand name Zolgensma, is used as a one-time infusion into the vein for the treatment of SMA. This drug contains SMN1 transgene along with synthetic promoters. Upon administration, this provides SMN1 transgene to the affected motor nerves. This results in increase in SMN protein. The cost of this life changing medication is Rs.18 Crore.