Angelman's syndrome and 15q11-q13 deletion.

We discuss the results of cytogenetic reinvestigation in 10 patients with Angelman's syndrome reexamined during the last year. A deletion with 15q11-13 could be demonstrated in 6 of them, confirming that with the available cytogenetic techniques a 15q11-13 deletion is visible and detectable in at least half of the patients with this MCA/MR syndrome. On the other hand, the deletion could not be seen in two affected siblings. This indicates that de novo visible 15q11-13 deletions with low recurrence risk and autosomal recessively inherited cases combine to give an overall sib recurrence risk of less than 25%.