Familial occurrence of Turner syndrome: casual event or increased risk?

Aim: The prevalence of Turner syndrome (TS) at birth has been estimated as approximately 1 in 2500 live female births. An increased risk of TS in subsequent pregnancies for couples who already have a daughter with TS has not been reported. Methods: We reviewed the records of 140 patients to evaluate the presence of familial TS occurrence. Results: Recurrence of TS was observed in 1.4% of our case series, which represents a 35-fold increased probability of having a second child with TS compared to no recurrence. Conclusion: This observation suggests that a risk of recurrence is possible, even though it is generally assumed that the likelihood of recurrent pregnancies with TS is similar to that in the general population. A wider study would be useful to confirm these data to improve genetic counseling for families with a daughter with TS.