There are three genetic types of Alport Syndrome. X-linked (related to the X chromosome) is the most common form of Alport Syndrome. About 80% of the people with this disease have the X-linked type. Boys with this type are severely affected and always develop kidney failure sometime in their lives. Girls with this type usually have milder symptoms than boys, but they can develop kidney failure. The rest of the people with Alport Syndrome have either the autosomal recessive type which affects 15 percent, or the autosomal dominant type, which affects 5 percent. If one parent has the disease and passes an abnormal gene to the child, it is called dominant inheritance. In other words, only one copy of the abnormal gene is needed to cause the disease. If both parents carry the abnormal gene, and both parents pass an abnormal gene to the child, it is called recessive inheritance. Both copies of the abnormal gene are needed to cause the autosomal recessive version of the disease.