Bardet-Biedl syndrome (BBS) has an autosomal recessive pattern of inheritance. 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% 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 Bardet-Biedl syndrome (fewer than 10%) appear to require the presence of at least three mutations for a person do 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: 7/18/2016
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