FTD can result in obvious shrinkage of the front of the brain
A gene that may give you an increased risk of a distressing early form of dementia has been identified by an international team of scientists.
Fronto-temporal dementia (FTD) is the second most common type of dementia in the under 65s and can result in a complete personality change.
The researchers studied the brains of 515 people with FTD and found the gene on chromosome 7.
A charity said this could open the door to new treatments for the disease.
Writing in the journal Nature Genetics, Professor Maria Grazia Spillantini, of the University of Cambridge, said her team had worked with an international collaboration with investigators in 11 countries including the UK, the US, Belgium and Spain.
They compared the brains of 515 people with known FTD with 2,509 brains of people without the condition.
They found several different mutations on chromosome 7 which are thought to affect around half of the people with FTD.
These mutations increase the amounts of the protein the gene codes for.
About 20% of individuals with FTD have another kind of genetic mutation known as a GRN mutation.
Professor Spillantini thinks that the new gene accelerates the harm caused by the GRN mutation and makes the disease progress faster: "We found a specific gene that was associated with an increased risk of the disease.
"A better understanding of how the gene is involved could identify a new approach to tackle this disease."
Rebecca Wood, chief executive of the Alzheimer's Research Trust which part funded the study, said fronto-temporal dementia was an extremely distressing disease that affects thousands of families in the UK.
"This significant new work adds to our understanding of the disease, and we hope it will boost research efforts," she added.
Dr Susanne Sorenson, head of research at the Alzheimer's Society, said this was not the first gene found to be associated with FTD: "A gene causing fronto-temporal dementia in some families was identified for the first time last year.
"This is very exciting news as finding out what the proteins produced by these genes do could help us understand the processes that cause the condition."