Is Joubert syndrome inherited ?
How is Joubert syndrome inherited? Joubert syndrome is predominantly inherited in an autosomal recessive manner. This means that to be affected, a person must have a mutation in both copies of the responsible gene in each cell. Affected people inherit one mutated copy of the gene from each parent, who is referred to as a carrier. Carriers of an autosomal recessive condition typically do not have any signs or symptoms (they are unaffected). When 2 carriers of an autosomal recessive condition have children, each child has a: 25% (1 in 4) chance to be affected 50% (1 in 2) chance to be an unaffected carrier like each parent 25% chance to be unaffected and not be a carrier. In rare cases, when Joubert syndrome is caused by mutations in the OFD1 gene on the X chromosome, it is inherited in an X-linked recessive manner. X-linked recessive conditions usually occur in males, who only have one X chromosome (and one Y chromosome). Females have two X chromosomes, so if they have a mutation on one X chromosome, they still have a working copy of the gene on their other X chromosome and are typically unaffected. While females can have an X-linked recessive condition, it is very rare. If a mother is a carrier of an X-linked recessive condition and the father is not, the risk to children depends on each child's sex. Each male child has a 50% chance to be unaffected, and a 50% chance to be affected Each daughter has a 50% chance to be unaffected, and a 50% chance to be an unaffected carrier If a father has the condition and the mother is not a carrier, all sons will be unaffected, and all daughters will be unaffected carriers.