SMA Type IV (Adult Onset)


Typically in the adult form symptoms begin after age 35. It is very rare for Spinal Muscular Atrophy to begin between the ages of 18 and 30. Adult SMA is characterized by insidious onset and very slow progression. The bulbar muscles, those muscles used for swallowing and respiratory function, are rarely affected in Type IV.

Adult Onset X-Linked SMA

This form also known as Kennedy's Syndrome or Bulbo-Spinal Muscular Atrophy, occurs only in males, although 50% of female offspring are carriers. This form of SMA is associated with a mutation in the gene that codes for part of the androgen receptor and therefore these male patients often have breast enlargement known as gynoecomastia. Also noticeably affected are the facial and tongue muscles. Like all forms of SMA the course of the disease is variable, but in general tends to be slowly progressive or nonprogressive.


There is nothing unusual or distinctive about the current management of the adult forms of Spinal Muscular Atrophy. Proper diagnosis, genetic counseling and appropriate physical therapy remain mainstays.