Hereditary motor sensory neuropathy with or without agenesis of the corpus callosum

Hereditary motor sensory neuropathy is one of the most common recessive genetic disorders in some regions of Québec:

• Saguenay–Lac-Saint-Jean;
• Charlevoix;
• Haute-Côte-Nord.

Hereditary motor sensory neuropathy is a neuromuscular disorder affecting the nerves responsible for body movements. The disorder is often accompanied by a defect in the corpus callosum, a structure that connects the two sides of the brain. In some affected people, the corpus callosum may be totally or partially missing. This defect is called “agenesis of the corpus callosum.” The symptoms of hereditary motor sensory neuropathy are the same in both forms of the disorder, that is, with or without agenesis of the corpus callosum.

The life expectancy of an affected person is around 33 years.

In children, the symptoms of hereditary motor sensory neuropathy are the following:

• lack of muscle tone after birth: the child’s body is more flaccid than normal
• delayed motor development: for example, the child sits and walks later than children of the same age
• mild or moderate cognitive delay: for example, it takes them longer to learn to speak than children of the same age.

There is no treatment to cure hereditary motor sensory neuropathy. Surgeries and different therapies can nevertheless help reduce or delay some of the symptoms of the disorder.

Teams of professionals in the health and social services system provide therapy and care for affected people. These teams consist of neurologists, nurses, physiotherapists, occupational therapists and orthopedists.

Over the years, hereditary motor sensory neuropathy can lead to the following complications in affected people:

• It becomes increasingly difficult for them to walk, because of their muscle weakness.
• Adolescents must use a wheelchair to get around
• Their hands and feet become deformed, along with their spinal cord (scoliosis).
• They may have relatively severe psychiatric problems. Nearly half of affected people have such problems in their adolescence and adulthood.
• They grow increasingly dependent on others, who must help them perform most activities of daily living.

Furthermore, children with neuropathy are enrolled in special education classes and rarely go beyond grade 2 of elementary school.

.Hereditary motor sensory neuropathy is a recessive genetic disorder

To find out more, see the page Transmission d’une maladie héréditaire récessive.

It is impossible to prevent hereditary motor sensory neuropathy in newborns who have received a copy of a defective gene from each of their two parents. However, the defective gene responsible for this disorder can be detected through a simple, quick and inexpensive screening test.

The Ministère de la Santé et des Services sociaux and the Centre intégré universitaire de santé et de services sociaux (CIUSSS) du Saguenay–Lac-Saint-Jean offer tests to detect the carriers of this disorder.

These tests are offered to anyone who:

• is over the age of 18 years
• wants children
• has at least one biological grandparent born in one of the following three regions:
  • le Saguenay–Lac-Saint-Jean,
  • Charlevoix,
  • la Haute-Côte-Nord.
  In these regions, 1 in 2100 newborns is affected with hereditary motor sensory neuropathy with or without agenesis of the corpus callosum. Furthermore, 1 in 23 people carries the defective gene responsible for this disorder. 

To learn more about carrier screening, see the page Offre de tests de porteur pour 4 maladies héréditaires récessives chez les personnes originaires des régions du Saguenay–Lac-Saint-Jean, de Charlevoix et de la Haute-Côte-Nord

To get help or more information on neuromuscular disorders such as hereditary motor sensory neuropathy, visit the following links:

• Dystrophie musculaire Canada (Muscular Dystrophy Canada) 
• Corporation de recherche et d’action sur les maladies héréditaires