Recurrence of Mowat–Wilson syndrome in siblings with the same proven mutation

Mowat–Wilson syndrome (MWS) is a mental retardation syndrome associated with distinctive facial features, microcephaly, epilepsy, and a variable spectrum of congenital anomalies, including Hirschsprung disease (HSCR), agenesis of the corpus callosum, genitourinary abnormalities, and congenital heart disease. Heterozygous mutations or deletions involving the gene ZFHX1B (previously SIP1 ) [OMIM 605802] have recently been found to cause MWS. There have previously been no reports of a sibling recurrence of this syndrome. A brother and sister are described with clinical features of MWS, where both have the same truncating mutation in exon 8 of ZFHX1B . As their parents are phenotypically normal and do not have the mutation in lymphocyte‐derived DNA, the most likely explanation is germ‐line mosaicism. © 2005 Wiley‐Liss, Inc.