Despite behavioral differences, individuals with Williams or Prader-Willi syndrome share a proneness to certain personality characteristics. We hypothesized that there are qualitative differences in these shared personality features. Personality-motivation (measured using the Reiss Profiles) was compared for equal numbers of age- and gender-matched individuals with Williams or Prader-Willi syndrome or mental retardation due to nonspecific causes. Each syndrome featured aberrant motivational profiles, and similarities were found across groups in various domains. Significant differences emerged in the specific stimuli that motivated behavior in several Reiss Profile domains. Implications are discussed for the "classic" sociable personality in Williams syndrome and for compulsivity in Prader-Willi syndrome. Recommendations are made for treatment and more refined phenotypic research.

Sex chromosomal aneuploidy is the most common disorder of sex chromosomes in humans, with an incidence of 1 in 400 newborns. The addition of more than one extra X and/or Y chromosome to a normal male karyotype is less frequent and has its own distinctive physical and behavioral profile. This study examines the behavioral similarities and differences in individuals with 48,XXYY compared to 48,XXXY and 49,XXXXY. The participants include 11 males with 48,XXYY and 13 males with 48,XXXY and 49,XXXXY. Using the Vineland Adaptive Behavior, the Achenbach Child Behavior Checklist, and the Reiss Personality Profiles, parents are asked to characterize the behavior and personality of their boys with sex chromosome tetrasomy and pentasomy. Males with 48,XXYY have higher overall adaptive scales in daily living skills, socialization, and communication compared to males with 48,XXXY and 49,XXXXY. Both groups are at risk for maladaptive behavior, although 48,XXYY males are at a higher risk for internalizing and externalizing symptoms. 48,XXXY and 49,XXXXY function at a lower cognitive level and their behavior is often immature for their chronological age. Both groups display interests in helping others, but have a low tolerance for being rejected or teased. Specific recommendations and interventional strategies are provided for individuals with 48,XXYY, 48,XXXY, and 49,XXXXY.

Background  This study explores everyday social competence in the lives of persons with three genetic intellectual disability syndromes. Methods  Using parent reports on the Social and Activity Competence domains of Achenbach's Child Behavior Checklist (CBCL), socially competent behaviours were examined in 58 persons with Williams syndrome, 54 persons with Prader‐Willi syndrome, and 65 persons with Down's syndrome. Results  The Down's syndrome group showed the highest overall social competence scores, while individuals with Prader‐Willi syndrome fared worst in terms of their behaviour with others. The Williams syndrome group scored lowest in terms of skill with jobs and chores, and the Down's syndrome group showed the least skill in non‐sport activities. Regarding specific activities, musical activities were popular in both Williams syndrome and Down's syndrome, but more participants with Williams syndrome played musical instruments. Compared with the other groups, individuals with Prader‐Willi syndrome were five to 25 times more likely to play with jigsaw puzzles, and those with Williams syndrome were least likely to engage in any visual–spatial leisure activities. Age was found to be a positive correlate of social competence for the Williams and Down's syndrome groups, but not for the Prader‐Willi group. Conclusions  Implications are discussed for interventions and for future behavioural phenotype work.

In this two-part study, we assessed musical involvements in two samples of persons with Williams syndrome compared to others with mental retardation and also related musicality to anxiety and fears in Study 2. Relative to others with mental retardation, those with Williams syndrome were more likely to take music lessons, play an instrument, and have higher ratings of musical skills. In the Williams syndrome groups only, fewer externalizing symptoms were associated with listening to music, whereas less anxiety and fewer fears were associated with the frequency, duration, and skill in producing music as well as emotional responses to negatively toned music. Implications are discussed for future research on musical processing, musical interventions, and well-being in Williams syndrome and other groups.