Background: Prader–Willi syndrome (PWS) is a rare neurodevelopmental disorder with symptoms that impact health and quality of life (QOL). There is limited data on global health, QOL and the relationship with mood in individuals with PWS. Methods: Parents completed three validated assessments, the Glasgow Depression Scale‐Carer Supplement (GDS‐CS), PROMIS Parent‐Proxy Global Health 7 and PROMIS Parent‐Proxy Life Satisfaction 8b, for 527 individuals with PWS. Results: Mean GDS‐CS score was 8.29 (SD 4.55), and 18% had a score of 13+, reflective of possible depression. Mean PROMIS Global Health and Life Satisfaction scores were 41.46 (SD 8.48) and 43.39 (SD 8.48), respectively, and are lower compared to the general population. Both PROMIS scales worsened with age, and scores on the PROMIS and GDS‐CS were associated with parent reports of depression for the person with PWS. Conclusions: These validated instruments may be useful for assessing mood and QOL in PWS.

Individuals with Prader–Willi syndrome (PWS) may be at higher risk of developing blood clots as compared to the typical population, but this risk is poorly understood. It is also unclear if laboratory testing of D-dimer concentration might be useful to screen for thrombosis in PWS. Here, we surveyed the thrombosis history of 883 individuals with PWS and evaluated the D-dimer concentration in a subset of 214 asymptomatic individuals, ages 5–55. A history of at least one blood clot was reported by 3.6% of respondents. Thrombosis increased with age, but no significant difference was found on the basis of sex or family history. Genetic subtype was a significant factor when considering only those with a known subtype, and individuals with a history of edema had significantly more blood clots. In the D-dimer sub-study, ≈15% of participants had high D-dimer concentrations, and 3.7% had D-dimer values more than twice the normal upper limit. One participant with a high D-dimer result was found to have a blood clot. No significant differences in D-dimer results were found on the basis of age, sex, genetic subtype, family history of blood clots, edema history, or BMI. The D-dimer test does not appear to be a sensitive and specific screening tool for blood clots in asymptomatic individuals with PWS.