What are the genetic changes related to GRN-related frontotemporal dementia ?
GRN-related frontotemporal dementia results from mutations in the GRN gene. This gene provides instructions for making a protein called granulin (also known as progranulin). Granulin is active in many different tissues in the body, where it helps control the growth, division, and survival of cells. Granulin's function in the brain is not well understood, although it appears to play an important role in the survival of nerve cells (neurons).  Most mutations in the GRN gene prevent any granulin from being produced from one copy of the gene in each cell. As a result, cells make only half the usual amount of granulin. It is unclear how a shortage of this protein leads to the features of GRN-related frontotemporal dementia. However, studies have shown that the disorder is characterized by the buildup of a protein called TAR DNA-binding protein (TDP-43) in certain brain cells. The TDP-43 protein forms clumps (aggregates) that may interfere with cell functions and ultimately lead to cell death. Researchers are working to determine how mutations in the GRN gene, and the resulting loss of granulin, are related to a buildup of TDP-43 in the brain.  The features of GRN-related frontotemporal dementia result from the gradual loss of neurons in regions near the front of the brain called the frontal and temporal lobes. The frontal lobes are involved in reasoning, planning, judgment, and problem-solving, while the temporal lobes help process hearing, speech, memory, and emotion. The death of neurons in these areas causes problems with many critical brain functions. However, it is unclear why the loss of neurons occurs in the frontal and temporal lobes more often than other brain regions in people with GRN-related frontotemporal dementia.