Table 1.

Hypotheses.

Research question	Hypothesis
(a)	Family members will experience PWS related events as a traumatic stressor and will suffer from higher levels of trauma symptoms than the general population, to an extent that they will meet the criteria of PTSD (DSM-5; American Psychiatric Association, 17).
(b)	Trauma symptom severity will be positively related to the experience of PWS-related trauma.
(c)	Trauma symptoms severity will be inversely correlated with experienced quality of life. This third hypothesis will be further investigated by studying the relationship between distinct clusters of trauma symptoms and domains of quality of life.
(d)	Relatives of PWS individuals aged 10 to 30 years will report higher degrees of PWS symptoms, more experienced PTSD symptoms, and lower quality of life than relatives of PWS individuals aged 0 to 9 years and PWS individuals aged older than 30 years.
(e)	Relationship between living situations and the occurrence (presence or absence) of trauma symptoms, and content of reported trauma (PWS-related or not) will be explored.