Werdnig-Hoffman disease (also known as "Severe infantile spinal muscular atrophy", or "spinal muscular atrophy type I") is an autosomal recessive neuromuscular disease. It is the most severe form of spinal muscular atrophy, which is one of a number of neuromuscular diseases classified as a type of muscular dystrophy.
Werdnig-Hoffman affects the lower motor neurons only.
Werdnig-Hoffman disease is inherited in an autosomal recessive pattern, which means the defective gene is located on an autosome, and two copies of the gene - one from each parent - are required to inherit the disorder. The parents of an individual with an autosomal recessive disorder both carry one copy of the defective gene, but do not have the disorder.
Tracheostomy is often (but not always) a part of the treatment plan.
The child is constantly at risk of respiratory infection and pneumonia.
Poor chewing and swallowing may lead to malnutrition; supplemental tube feedings may be required through the nose or directly into the stomach.
Recurrent respiratory problems (the primary cause of morbidity in this condition) mean that mechanical support for breathing—usually initially in the form of BiPAP and later often tracheostomy and ventilation—are necessary for the baby to have any chance of long-term survival.
Affected children never sit or stand and usually die before the age of 2 without breathing support.
However, some individuals have survived to become adults, in which case sexual function is unimpaired.