Most people―including doctors and nurses―are generally unaware of one of the most common genetic disorders called spinal muscular atrophy (SMA), which affects 1 in every 6,000 infants. August is National Awareness Month for SMA, and raising awareness is critical to finding treatments and a cure for this disease that mainly affects infants and children.
Since the identification of the gene responsible for SMA in the mid-1990s, many advances have been made in the understanding of this serious disease. As indicated by the name of the responsible gene, the survival motor neuron (SMN1) gene, SMA is a neuromuscular disease. In this potentially lethal disease, major physical disabilities result from the deleterious effects on muscles. SMA does not affect sensation or cognition, however, and children with SMA are highly intelligent and sociable.
SMA consists of 4 major types with a single underlying genetic cause and a wide spectrum of manifestations. The types of SMA are correlated with age of onset and severity of symptoms. Infants with SMA Type I are born with feeding and breathing problems and weak muscles. The onset of SMA Type II occurs between 6 and 18 months of age, and these children have delayed motor milestones and a range of physical disabilities. SMA Type III is typically diagnosed by 3 years of age but also as late as the teenage years. These children face difficulty running, climbing steps, or rising from a chair. Type IV, the adult form, is characterized by mild motor impairment and weakness and is much less common than the other types of SMA.
There is no cure or effective treatment for SMA. The mainstay of therapy is supportive care, with a multidisciplinary approach to manage symptoms and prevent complications. In recent years, a growing trend in proactive clinical care has increased survival, especially in patients with SMA Type I.
The discovery of the underlying SMN1 mutation has resulted in huge strides in research into orphan drugs for this rare disease compared with 10 years ago, when only 1 drug program existed. Today, 15 novel SMA therapeutic programs are in various stages of preclinical and clinical development and 5 drugs are in active clinical trials. Funding and resources from the government and pharmaceutical industry have increased greatly, and 12 pharmaceutical companies are actively investing in the SMA pipeline of drugs.
Ongoing clinical trials in children are testing the benefits of existing drugs that show promise in treating the symptoms of SMA such as hydroxyurea, valproic acid, and phenylbutyrate. The rapidly advancing development of new drugs for SMA has used a broad range of strategies such as small molecule SMN enhancers, neuroprotectants, SMN2 gene splicing correctors, stem cell therapy, and gene therapy.
Raising awareness of SMA is important to follow through on and expand the recent progress in drug development and patient care. Since 1996, the organization Families of Spinal Muscular Atrophy has been coordinating a National Awareness Month for SMA. Families of Spinal Muscular Atrophy can provide information, ideas, and materials to help increase awareness of this life-threatening disease.