BBS has an autosomal recessive pattern of inheritance. This means that to have the syndrome, a person must have a mutation in both copies of the responsible gene in each cell. People with BBS 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% chance to be affected
50% chance to be an unaffected carrier like each parent
25% chance to be unaffected and not a carrier
Some cases of BBS (fewer than 10%) appear to require the presence of at least three mutations for a person to have features of the condition. This is known as triallelic inheritance. In these cases, in addition to inheriting a mutation in the same gene from each parent, a child also needs to have at least one more mutation in another gene to be affected.
Last updated: 9/18/2017
We hope this information is helpful. We strongly recommend you discuss this information with your doctor. If you still have questions, please