The purpose of this study is to characterize the symptoms of Zellweger Spectrum Disorder (ZSD) and related peroxisome disorders, and to assess the quality of life of family caregivers (parents, stepparents, legal guardians) of patients diagnosed with ZSD or a related peroxisome disorder. All family caregivers of patients enrolled in the Rare Diseases Clinical Research Network (RDCRN) Contact Registry who are diagnosed with ZSD or a related peroxisome disorder will be invited via email to participate in this study.

A total of three online surveys will be provided to each family caregiver that fits the inclusion criteria and is enrolled in the RDCRN STAIR Contact Registry. All three surveys should take approximately 60 minutes total to complete.

The first survey included is the ZSD Symptom Inventory, which is comprised of both multiple choice and open-ended responses. The survey asks family caregivers multiple questions regarding their child's mobility, balance, vision, and hearing status, as well as when they were diagnosed, test results, and past and present symptoms. This survey was adapted from an instrument that was developed by a physician-researcher in the field of ZSD to correlate caregiver-reported symptoms of ZSD to metabolic markers of ZSD (Wangler et al. Manuscript submitted, Pediatrics). For the purpose of this study, the survey was expanded to include domains that were determined based on existing literature on clinical symptoms of ZSD as well as input from both expert clinicians in the field and parents of children diagnosed with ZSD. Both clinicians and parents were in agreement that the questions included in the survey were comprehensive, appropriate and relevant for ZSD. Additionally, pilot testing of this survey to 34 family ZSD caregivers (26 parents of living children, 8 parents of deceased children) provided feedback on increasing the answer choice options for the survey, and adding more open-ended questions. This survey will take an estimated 40 minutes to complete. Family caregivers of living and deceased children will take this survey, and the tense and recall language will be modified to accommodate each of these experiences.

The second survey is the Pediatric Inventory for Parents (PIP) Survey. It includes 42 Likert-scale questions; for each question asked, two sets of responses need to be completed, including responses to "how often" and "how difficult" each topic is for the patient or family caregiver over a given period of time. The PIP measures four domains including communication, medical care, emotional distress, and role function. This instrument has been validated to assess caregiver burden in multiple pediatric chronic illnesses, including type I diabetes, inflammatory bowel disease, and multiple congenital disorders including mitochondrial disease. Although this is validated in parents of living children with pediatric illnesses, the investigators will also be administering a modified PIP to ZSD family caregivers of deceased children, asking them to recall their experience over the last 12 months of their child's life. The PIP takes an estimated 10 minutes to complete.

The third survey is the Family Quality of Life (FQOL) Survey. It includes 25 Likert-scale questions, regarding how parents/primary caregivers feel about his or her life together as a family over a given period of time. The FQOL measures 5 domains including family interaction, parenting, emotional well-being, physical/material well-being, and disability-related support, and has been validated for use in families of children with disabilities. Although this is validated in parents of living children with disabilities, the investigators will also be administering a modified FQOL to ZSD family caregivers of deceased children, asking them to recall their experience over the last 12 months of their child's life. The FQOL takes less than 10 minutes to complete.

The PIP and the FQOL were chosen for this study as they are validated tools for assessing quality of life in caregivers for chronic pediatric illnesses (PIP) and for children with disabilities (FQOL). Although many of these diseases that have been used for validation of these instruments are clinically distinct from ZSD, we expect there to be similarities in the caregiver experience between ZSD and these diseases in the domains of communication, medical care, emotional distress, family interaction, parenting, physical well-being and disability-related support. As a rare disease, the relatively low prevalence of the ZSD and likely decreased awareness may affect certain domains differently than the more common diseases that have been studied using these tools. Nevertheless, the PIP is one of the most commonly used survey tools for caregiver quality of life in chronic pediatric illnesses [8]. The FQOL is currently one of the only tools for assessing quality of life in caregivers for children with disabilities. This is one of the first studies assessing quality of life in families affected by ZSD; the information gained from this study can be used to help shape future quality of life studies in ZSD and other rare disease populations as well as ultimately be used to determine the impact of the disease and emerging treatments.

All participants will have 2 months from the time that they complete the consent form to complete all 3 surveys. Recruitment for the study will close 6 months from the survey launch date.

The survey data will be stored by the RDCRN's Data Management and Coordinating Center (DMCC) at the University of South Florida (USF). The RDCRN Contact Registry collects the names, phone numbers, and addresses of registrants. All data collected will be sent to the database of Genotypes and Phenotypes (dbGaP) to be stored indefinitely.

Inclusion Criteria:

• Family caregiver (parents, stepparents, legal guardians) of child (living or deceased) diagnosed with ZSD, acyl CoA oxidase (ACOX) deficiency or D-bifunctional protein deficiency (DBPD)
• Family caregiver is able to complete surveys

Exclusion Criteria:

• Inability of family caregiver to provide informed consent and complete survey
• Parents/primary caregivers of children who have not been diagnosed with ZSD, acyl CoA oxidase deficiency and D-bifunctional protein deficiency

Family caregivers (parents, stepparents, legal guardians) of patients (living or deceased) with ZSD or related peroxisome disorder diagnosis