Spinal muscle atrophy, or SMA, is a neuromuscular disorder that appears to one in every 6,000 or 10,000 babies worldwide. It is a rare condition characterized by weakness and size reduction of muscles. This is an already rare condition, but cases where adults are affected, are even rarer. Nerves called motor neurons, which is located between the spinal cord and lower part of the brain, cannot send signals to muscles. Movements are limited, which makes the muscles waste away or atrophy. SMA is caused by a problem in the SMN1 gene, which is a lack of protein required to make the motor neurons work normally.

There are four different SMA types, which are categorized based on the age and the severity of the disease. Diagnosis is available through genetic testing or a muscle biopsy. Genetic Testing is done by testing the status of the SMN1 gene. A muscle biopsy needs a small sample of muscle tissue which is then checked under a microscope. SMA types are as follows:

1. Type I (Werdnig-Hoffmann disease)
Also known as the “Floppy Baby Syndrome”, this type’s usual age of onset is between 0-6 months. This is considered as the most severe type of Spinal Muscular Atrophy because infants who are born in this condition usually die within weeks of diagnosis. Patients generally do not live past two years of age. Only 10% of infants with Werdnig-Hoffmann disease live into adolescence and adulthood, surviving the first years of their lives with respiratory support.

2. Type II (Dubowitz disease)
Dubowitz disease usual age of onset is between 6 to 18 months and is known as the intermediate type. Children who are diagnosed with this disease are usually not able to walk or stand, but can maintain a sitting position. Body muscles are weak and will gradually grow weaker over time. Maintenance is needed to avoid weakness progression. Children with this type can reach adulthood with reduced lifespan, and in some cases, are also diagnosed with Scoliosis.

3. Type III (Kugelberg-Welander disease)
Also known as Juvenile Spinal Muscular Atrophy., Kugelberg-Welander disease is diagnosed after more than 12 months of birth. Children who are diagnosed with this disease can usually walk and function like a normal child for a while. However, after 12 months, symptoms will start manifesting.

Juvenile spinal muscular atrophy. victims will lose the ability to walk and other motor functions. Fortunately, unlike the two previous types, the life expectancy of patients under this type is normal. Respiratory problems are also not as severe as the other types.

4. Type IV
Last but not least is the adult-onset Type IV, which can also be classified as late-onset Type III. Symptoms usually appear during the 30s and effects of proximal muscles. Patients with this type often need a wheelchair for mobility. Life expectancy is normal and no other complications are associated with this type.

There is still no standard cure for SMA, but there are treatments that may help improve the mobility of patients with the condition. One of the newest treatments is a drug called Nusinersen, which is a treatment that was approved last 2016 and increases protein to fill the SMN1 gene function. For those with respiratory problems, breathing support is usually given. Proper nutrition is also vital and consumed through a feeding tube if necessary.