Spinal Muscular Atrophy (SMA)

Steven Beuerlein

Location

Phoenix, AZ

Steven created this artwork at age 10 while attending the 1999 MDA summer camp in Heber, Ariz. His favorite hobbies include drawing, swimming and riding horses.

Full name: 
Steven Beuerlein
Artist: 
Steven Beuerlein
Medium: 
Crayon

Melina Fatsiou

Location

Huntsville, AL

Melina has proficiency certificates in English from Cambridge and Oxford Universities, and attended the Panteion University of Athens. She enjoys painting and sketching, and has participated in a number of art exhibits. She also has written and published literature.

Full name: 
Melina Fatsiou
Artist: 
Melina Fatsiou
Medium: 
Acrylic

Research Briefs: FA, MG, MM, MMD1, gene therapy

Edison drugs target FA, mitochondrial diseases

Causes/Inheritance

Motor neurons
Muscle-controlling nerve cells (motor neurons) are located mostly in the spinal cord. Long, wirelike projections connect the motor neurons to muscles in the limbs and trunk. Normally, signals from the neurons to the muscles cause muscles to contract. In SMA, motor neurons are lost, and muscles can’t function.

Diagnosis

The first steps in diagnosis of a neuromuscular disease are usually an in-office physical examination and family history, with some simple tests to distinguish spinal muscular atrophy (SMA) from similar conditions (such as muscular dystrophy).

Signs and Symptoms

SMA linked to chromosome 5 (SMN-related), types 1-4

In SMA types 1 through 4, symptoms vary on a continuum from severe to mild, based on how much SMN protein there is in the nerve cells called motor neurons. (SMN stands for survival of motor neuron.) The more SMN protein there is, the later in life symptoms begin and the milder the course of the disease is likely to be. 

Forms of SMA

SMA linked to chromosome 5

Spinal muscular atrophy types 1 through 4 all result from a single known cause — a deficiency of a protein called SMN, for "survival of motor neuron."

Deficiency of SMN protein occurs when a mutation (flaw) is present in both copies of the SMN1 gene — one on each chromosome 5. Normally, most of the protein made from SMN1 genes is full-length and functional, but when mutations occur, little or no full-length, functional SMN protein is produced.

Overview

What is spinal muscular atrophy?

Muscles affected in SMA
The muscles closer to the center of the body (proximal muscles) are usually more affected in spinal muscular atrophy than are the muscles farther from the center (distal muscles).

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