Is Dopa-responsive dystonia inherited ?
How is dopa-responsive dystonia inherited? Depending on the genetic cause of dopa-responsive dystonia (DRD), it may be inherited in an autosomal dominant or autosomal recessive manner. When DRD is caused by mutations in the GCH1 gene, it is inherited in an autosomal dominant manner. This means that having a mutation in only one of the 2 copies of the gene is enough to cause signs and symptoms of the disorder. In some cases, an affected person inherits the mutation from an affected parent; other cases result from having a new (de novo) mutation in the gene. When a person with an autosomal dominant condition has children, each child has a 50% (1 in 2) chance to inherit the mutated gene. Some people who inherit a mutated GCH1 gene never develop features of DRD; this phenomenon is known as reduced penetrance. When DRD is caused by mutations in the TH gene, it is inherited in an autosomal recessive manner. This means that a person must have mutations in both of their copies of the gene to be affected. The parents of a person with an autosomal recessive condition usually each carry one copy of the mutated gene and are referred to as carriers. Carriers typically do not have signs or symptoms. When parents who are both carriers of an autosomal recessive condition have children, each child has a 25% (1 in 4) chance to be affected, a 50% chance to be an unaffected carrier like each parent, and a 25% chance to be unaffected and not be a carrier. When DRD is caused by mutations in the SPR gene, it can be inherited in an autosomal recessive or autosomal dominant manner.