We report a girl who had Hirschsprung disease in association with distinct 
facial appearance, microcephaly, agenesis of the corpus callosum and mental 
retardation (Mowat-Wilson syndrome). Mutation analysis of the zinc finger homeo 
box 1 B (ZFHX1 B) gene revealed a de novo 7 bp deletion (TGGCCCC) at nucleotide 
1773 (1773 delTGGCCCC) resulting in a frameshift and leading to a termination 
codon at amino acid residue 604 (604 X) in exon 8 C. The zinc finger homeo box 1 
B (Smad interacting protein-1) is a transcription corepressor of Smad target 
genes with functions in the patterning of neural crest derived cells, CNS, and 
midline structures. Mutations in ZFHX1 B can lead to neurological disorders in 
addition to dysmorphic features, megacolon, and other malformations.