Note: This text is taken from the "Families of SMA" website which may be found at: http://www.fsma.org/
Quick Facts about Spinal Muscular Atrophy
THE DISEASE
Spinal muscular atrophy (SMA), the number one genetic killer of children under the age of two, is a group of inherited and often fatal diseases that destroys the nerves controlling voluntary muscle movement, which affects crawling, walking, head and neck control, and even swallowing.
WHO IS AFFECTED?
SMA is one of the most prevalent genetic disorders.
- One in every 6,000 babies is born with SMA. Of children diagnosed before
age two, 50 percent will die before their second birthday.
- SMA can strike anyone of any age, race or gender.
- One in every 40 people carries the gene that causes SMA. The child of
two carriers has a one in four chance of developing SMA.
THE TYPES OF SMA
- Type 1, or Werdnig-Hoffmann Disease, is the most severe form of SMA.
Children with Type I tend to be weak and lack motor development, rendering
movement difficult. Children afflicted with Type I cannot sit unaided
and have trouble breathing, sucking and swallowing. Type I SMA strikes infants
between birth and six months.
- Type II is slightly less severe. Type II patients may be able to
sit unaided or even stand with support and usually do not suffer
from feeding and swallowing difficulties. However, they are at increased risk
for complications from respiratory infections. Type II SMA affects infants
between seven and 18 months old.
- Type III, also known as Kugelberg-Welander Disease, is the least
deadly form of childhood-onset SMA. Type III patients are able
to stand, but weakness is prevalent and tends to eventually sentence its victims
to a wheelchair. Type III SMA strikes children after the age of 18 months,
but can surface even in adulthood.
- Type IV is the adult form of the disease in which symptoms tend
to begin after age 35. Symptoms usually begin in the hands, feet and tongue,
and spread to other areas of the body.
- Adult Onset X-Linked SMA, also known as Kennedy's Syndrome or Bulbo-Spinal
Muscular Atrophy, occurs only in men. Facial and tongue muscles
are noticeably affected. In addition, these men also often have breast enlargement
known as gynecomastia. Like all forms of SMA, the course of the disease
is variable, but in general tends to progress slowly.
SMA does not affect sensation and intellectual activity in patients. It
commonly is observed that patients with SMA are unusually bright and sociable.
RESEARCH
- In 1999, investigators at The Ohio State University replicated SMA in
a mouse model. The researchers have demonstrated that when the mice have high
amounts of the SMN2 gene, which is present in all human SMA patients,
the SMA phenotype is corrected and they develop normally. These findings support
the conclusion that large amounts of the protein could act to prevent the
damage caused by SMA or even reverse the impact of the disease.
- Since then, many more important research steps have been made. For details,
please see SMA Research. The
current focus of research is on finding an effective treatment
for SMA.
- This research was funded in large part by the volunteer driven, not-for-profit
organization Families of SMA - http://www.fsma.org
TESTING
Prenatal counseling is available to couples who are carriers of SMA or who
have lost a child to SMA. For details, please see SMA
Genetics.
(Text courtesy "Families of SMA" web site)