What are the genetic changes related to Kufs disease ?
Mutations in the CLN6 or PPT1 gene cause Kufs disease type A, and mutations in the DNAJC5 or CTSF gene cause Kufs disease type B. Most of the proteins or enzymes produced from these genes are involved in breaking down proteins or clearing unneeded materials from cells.  The CLN6 gene provides instructions for making a protein that likely regulates the transport of certain proteins and fats within the cell. Based on this function, the CLN6 protein appears to help in the process of ridding cells of materials they no longer need.  The PPT1 gene provides instructions for making an enzyme called palmitoyl-protein thioesterase 1. This enzyme is found in structures called lysosomes, which are compartments within cells that break down and recycle different types of molecules. Palmitoyl-protein thioesterase 1 removes certain fats from proteins, which probably helps break down the proteins.  The protein produced from the DNAJC5 gene is called cysteine string protein alpha (CSP). This protein is found in the brain and plays a role in the transmission of nerve impulses by ensuring that nerve cells receive signals.  The enzyme produced from the CTSF gene is called cathepsin F. Cathepsin F acts as a protease, which modifies proteins by cutting them apart. Cathepsin F is found in many types of cells and is active in lysosomes. By cutting proteins apart, cathepsin F can break proteins down, turn on (activate) proteins, and regulate self-destruction of the cell (apoptosis).  Mutations in the CLN6, PPT1, DNAJC5, or CTSF gene usually reduce the activity of the gene or impair the function of the protein or enzyme produced from the gene. In many cases, these mutations cause incomplete breakdown of certain proteins and other materials. These materials accumulate in the lysosome, forming fatty substances called lipopigments. In other cases, it is unclear what causes the buildup of lipopigments. In Kufs disease, these accumulations occur in nerve cells (neurons) in the brain, resulting in cell dysfunction and eventually cell death. The progressive death of neurons leads to the signs and symptoms of Kufs disease.  Some people with either type of Kufs disease do not have an identified mutation in any of these four genes. In these individuals, the cause of the condition is unknown.