For many years now, researchers worldwide have been trying to identify the main genetic trait responsible for the development of two related neurological diseases, amyotrophic lateral sclerosis (ALS) and frontotemporal dementia (FTD). ALS usually occurs after the age of 50 years and is caused by the degeneration of the neurons in the spinal cord that control the muscles. In FTD, dementia occurring before the age of 65 years, the loss of neurons leads to behavioral changes, language dysfunction and memory loss. Both disorders are known to have a high degree of overlap in the way they manifest themselves and in their underlying disease mechanisms. It now appears that the defect in a specific gene (C9orf72) on chromosome 9 is responsible for the occurrence of both ALS and FTD in families. “This genetic trait has been found in a large number of families with the combined disorder, including a Dutch family”, says John van Swieten, neurologist at Erasmus MC.
The genetic defect is common in the hereditary variant of the disease. Approximately 20-30 percent of the patients have the gene defect. But patients who do not have the hereditary variant of the disease also appear to be able to have this gene defect. The discovery is a giant leap forward in the knowledge on neurological disorders. “Identifying mutations in this gene has given scientists a new lead in carrying out research on the development of the disease”, says Peter Heutink, geneticist at VUmc and affiliated to the VUmc Alzheimer center. This knowledge on the development of the disease is indispensible in developing a treatment for the diseases. There is currently no treatment for the diseases.
Another research group from Jacksonville, USA (Mayo Clinic) has carried out a similar study independently of VUmc and Erasmus MC. The findings of this group, led by a Dutch researcher, were the same. These researchers will also publish their results today in the journal Neuron.