Accessory nipple as key symptom in diagnosis of Mowat-Wilson syndrome

Mowat-Wilson syndrome (MWS) is a rare congenital syndrome caused by a defect of the ZFHX1B (SIP1) gene on chromosome 2q22-q23. MWS is characterized by moderate-to-severe intellectual deficiency, epilepsy, a distinct facial phenotype and variable other malformations.

We report on a 15 years old boy with previously unclassified retardation-epilepsy-dysmorphism syndrome. The boy also has a ventricular septal defect and a hypospadia. Beside characteristic facial features like large uplifted ear lobes, an accessory right nipple was seen. The combination of mental retardation, epilepsy and accessory nipple in OMIM database lead to MWS as only possible diagnosis. Molecular genetic studies demonstrated a new heterozygous truncating mutation (frameshift mutation) in exon 8 of ZFHX1B gene. Although the incidence of accessory nipples in MWS is not known, its presence may be a key finding in clinical diagnosis of MWS within the large spectrum of retardation-epilepsy-dysmorphism syndromes.