Mainstreaming genomic testing for paediatric inborn errors of immunity

Abstract

Background: A mainstreaming model-of-care (MoC) was established in Queensland, Australia to support genomic testing (GT) for paediatric inborn errors of immunity (IEI). The model's feasibility and acceptability among clinicians and families have previously been demonstrated. However, its long-term impact remains unknown, and this clinical cohort has not yet been characterised within an Australian context. This study aimed to i) evaluate the long-term impact of the MoC on GT practices and patient outcomes ii) describe the first Australian cohort of paediatric IEI Methods: A retrospective audit and chart review were conducted to identify all instances of paediatric IEI GT in Queensland from 2017'2024. Data collected included demographics, indication for GT, GT instances, testing modality, results, and testing outcomes. GT ordering and interpretation behaviours were reviewed to evaluate the impact of the MoC. Results: 261 patients were identified as meeting the inclusion criteria for the audit. The mean age of GT was seven years, and the most common indication for testing was inflammatory bowel disease (n = 25, 14%). There was a linear increase in the number of patients tested from 2017'2018 (n = 40) to 2021 (n = 50), which reduced post-MoC implementation (n = 36 2022; n = 37 2023; n = 26 2024). Diagnostic rates improved post-MoC implementation, at 18% and 23%, respectively. Improved documentation related to GT was noted, including recording informed consent, results, variant interpretation, and familial considerations. Conclusion: A mainstreaming MoC improves paediatric IEI GT practices. Developing an IEI database will allow for ongoing tracking of GT, description of clinical cohort, and evaluation of future services.