Objectives:Several studies have suggested the different clinical features between 15q paternal deletion and maternal uniparental disomy (mUPD) of Prader-willi syndrome (PWS).Our objective was to appraise evidence on the association of genetic subgroups and intellectual abilities, psychiatric illness through meta-analysis.Methods: The electronic databases searched were PubMed and EMBASE from 1966 to March 2012.Studies that reported IQ and psychiatric illness or clinically relevant outcomes and information on 15q deletion and mUPD of PWS were included.Meta-analyses were performed by using fixed effect model, mean difference, odds ratio and 95 % confidence interval were calculated.Results: We retrieved 13 studies of 744 patients with PWS, including 423 of 15q deletion and 318 of mUPD.11 studies reported IQ in different subgroups, in comparison with mUPD, PWS patients with 15 q deletion associated with lower FSIQ (NM,-2.69 ; 95 % CI,-4.86 to-0.52 ; P =0.02), lower VIQ (NM,-7.5; 95%CI,-9.75 to-5.26; P<0.00001), and higher PIQ (NM, 4.02; 95%CI, 1.13 to 6.91; P =0.006).Five studies reported psychosis in the two subgroups, in comparison with 15q deletion, PWS patients with mUPD associated with higher risk of psychiatric illness (OR, 0.14;95%CI, 0.08 to 0.23; P <0.00001), higher risk of bipolar (OR, 0.04; 95%CI, 0.01 to 0.23; P=0.0002).Conclusions:These findings may help clinicians identify possible intervention strategies and supports based on the intellective ability associated with genetic subtype in individuals with PWS.Psychiatric examination should be part of general management of PWS, especially when caused by mUPD.