Do both parents need to pass on the gene mutation in order for a child to develop dystonia?
No, not usually. Early-onset dystonia is known as a dominant disorder. This means that only one copy of the abnormal gene is needed in order for an individual to inherit the potential to show symptoms. Some other genetic disorders, but not heritable dystonias (except for rare cases of DRD) are termed recessive. This means that two abnormal copies of the abnormal gene are needed before a person develops the disorder. Early-onset dystonia is also an autosomal disorder, meaning the gene is not carried on the chromosomes that determine an individual gender or sex (i.e., the X or Y chromosomes). Consequently, individuals of both sexes may develop the disorder and either parent may pass on the gene to their offspring. In contrast, an X-linked recessive gene is more likely to be expressed in males. X-linked dominant genes are usually lethal in males.
