Question: How many people are affected by Marinesco-Sjgren syndrome ?
Answer: Marinesco-Sjgren syndrome appears to be a rare condition. More than 100 cases have been reported worldwide.
Source: GHR

Question: What are the genetic changes related to Marinesco-Sjgren syndrome ?
Answer: Mutations in the SIL1 gene cause Marinesco-Sjgren syndrome. The SIL1 gene provides instructions for producing a protein located in a cell structure called the endoplasmic reticulum. Among its many functions, the endoplasmic reticulum folds and modifies newly formed proteins so they have the correct 3-dimensional shape. The SIL1 protein plays a role in the process of protein folding. SIL1 gene mutations result in the production of a protein that has little or no activity. A lack of SIL1 protein is thought to impair protein folding, which could disrupt protein transport and cause proteins to accumulate in the endoplasmic reticulum. This accumulation likely damages and destroys cells in many different tissues, leading to ataxia, myopathy, and the other features of Marinesco-Sjgren syndrome. Approximately one-third of people with Marinesco-Sjgren syndrome do not have identified mutations in the SIL1 gene. In these cases, the cause of the condition is unknown.
Source: GHR