What is the risk of recurrence in a subsequent pregnancy?
• In cases where the affected individual is the only one in the family: If this is the first case in the family and it is the isolated (non-syndromic) type of polydactyly, there is a high probability that the condition in the child/fetus is the result of a new mutation in the gene for polydactyly – i.e. the hereditary transmission starts with the child/fetus, and there is a 50% chance in every pregnancy that he or she will transmit the abnormal gene to his or her offspring. On the other hand, in these cases, the parents and other family members who are not offspring of the patient apparently have no increased risk for having another affected child. • In cases where there are many affected individuals in the family: The situation is different if there are already other cases in the family, because here one of the parents of each affected individual also carries an abnormal gene for polydactyly, and the risk of transmitting this to the offspring is 50% in every pregnancy, although it may
