Can new-born screening enhance outcomes for Spinal muscular atrophy?

Spinal muscular atrophy (SMA) is a rare genetic disease with a devastating outcome. It is one of the commonest fatal genetic diseases of infants with an incidence of 1 in 7000 to 10,000 live births. There is a high carrier frequency of the defective gene, and one Indian study found it in 1 in 30 individuals from the reproductive age group. The disease leads to progressive irreversible loss of the motor neurons. A very high mortality has been seen in the early onset subtypes while significant morbidity occurs in the late onset subtypes. New disease-modifying treatments have recently been approved and have been a gamechanger in the natural history of this disease.

In SMA, time is crucial for the motor neurons. The landmark studies which led to approval of the three newer therapies and the real-life experiences of their use have reiterated that outcome after treatment is best when administered very early in life before any loss of neurons. If the diagnosis is made at birth and treatment given before onset of symptoms, near normal developmental outcomes are witnessed.

Those treated after the symptom onset seldom achieve independent walking, if this was not acquired before the onset of the disease. Unfortunately, a significant time gets lost before a confirm diagnosis of SMA is made in many patients. This leads to suboptimum results despite use of these exorbitantly expensive treatments. Evolution of a fatal disease to a more chronic one with a lifelong disability has a tremendous impact on health care resources and a huge financial and psychosocial burden on the affected families.

This highlights the role of newborn screening (NBS) for the diagnosis of SMA. NBS is a simple test and should be introduced in all countries where therapy is available. Many countries (Canada, Japan, Belgium, Italy, Germany, Australia etc) have already adopted NBS for SMA and those detected positive are immediately given the disease modifying therapies. Implementation of NBS programs has helped facilitate early diagnosis and treatment, but challenges remain in overcoming administrative and procedural obstacles that can lead to treatment delays.

Many developed nations have centrally funded health care systems making therapy accessible to all. Even though the cost of NBS is low and benefits are obvious, identifying more patients than the system can treat is often reported in large middle-income countries. In a developing country like India, newborn screening may help diagnose SMA early, but raising humongous funds to procure these treatments may markedly delay their administration leading to suboptimal results.

Unless the costs of these therapies are significantly reduced or the treatments funded by health authorities, newborn screening for SMA may not give the expected good outcomes in the developing world.


The future however appears promising especially if the disease-modifying therapies become more affordable, are funded and diagnosis of SMA is made early in the presymptomatic stage by NBS leading to amelioration of the overall burden of the disease.

(Author: Dr. Neelu Desai, Consultant - Pediatric Neurologist and Epileptologist, P. D. Hinduja Hospital & MRC)