WAS is a rare primary immune deficiency disease caused by genetic mutation and is more common in males than females. The purpose of this study is to understand experiences of WAS subjects and caregivers to identify important concepts of interest that could be measured in future Phase IIIb trials. This is a qualitative cross-sectional study that will include a sample of approximately, 8 subjects with WAS and 13 caregivers of subjects with a diagnosis of WAS in the United States, United Kingdom and France. A 60 to 90 minute open-ended interview will be conducted over the telephone or video conference that will be audio-recorded for subsequent transcription. The aim of these interviews is to obtain subject and caregiver perspectives on the impact of WAS and its associated treatments on quality of life and experiences of living with WAS.

Inclusion Criteria:

Subjects:

• Male adolescents or young adults ranging in age from 12 through 30 years old.
• Diagnosis of WAS defined by WAS genetic mutation with a clinical score >=1 or self-reported disease severity.
• Subjects who are "conservatively managed" or have not received treatment for WAS; a maximum of 5 subjects who have received a hematopoietic stem cell transplant within the preceding two years.
• Able to read, speak, and understand English or French sufficiently to complete all assessments.
• Willing and able to participate in an audio-recorded, telephone or video conference session, including adherence to the interview instructions and completion of all questionnaires.
• Parent/guardian/patient signed informed consent.

Caregivers:

• Caregivers of children >=2 years of age diagnosed with WAS; at least 5 caregivers of subjects under the age of 8.
• Caregivers of subjects with a diagnosis of WAS defined by WAS genetic mutation with a clinical score >=1 or self-reported disease severity.
• Caregivers of subjects who are "conservatively managed" or have not received treatment for WAS; At least 2 caregivers of subjects who have received a hematopoietic stem cell transplant within the preceding two years.
• Caregivers are defined as primary caregiver.
• Able to read, speak, and understand English or French sufficiently to complete all assessments.
• Willing and able to participate in an audio-recorded, telephone or video conferencing interview session, including adherence to the interview instructions and completion of all questionnaires.
• Caregivers of Wiskott-Aldrich patients can be of any age or gender and do not have to follow the patient inclusion criteria, as long as their child/patient meets the inclusion criteria, as outlined.

Exclusion Criteria:

Subjects

• Subjects who have previously received gene therapy treatment Caregivers
• Caregivers of subjects who have previously received gene therapy treatment
• Professional caregivers (that is, at home nurse or equivalent).

A convenience sample of approximately, 21 subjects with WAS and primary caregivers of WAS subjects will be included in the study.