Partial duplications of the long arm of chromosome 3, dup(3q), are a rare but 
well-described condition, sharing features of Cornelia de Lange syndrome. Around 
two thirds of cases are derived from unbalanced translocations, whereas pure 
dup(3q) have rarely been reported. Here, we provide an extensive review of the 
literature on dup(3q). This search revealed several patients with caudal 
malformations and anomalies, suggesting that caudal malformations or anomalies 
represent an inherent phenotypic feature of dup(3q). In this context, we report 
a patient with a pure de novo duplication 3q26.32-q27.2. The patient had the 
clinical diagnosis of Currarino syndrome (CS) (characterized by the triad of 
sacral anomalies, anorectal malformations and a presacral mass) and additional 
features, frequently detected in patients with a dup(3q). Mutations within the 
MNX1 gene were found to be causative in CS but no MNX1 mutation could be 
detected in our patient. Our comprehensive search for candidate genes located in 
the critical region of the duplication 3q syndrome, 3q26.3-q27, revealed a so 
far neglected phenotypic overlap of dup(3q) and the Pierpont syndrome, 
associated with a mutation of the TBL1XR1 gene on 3q26.32.