P12 Transition to a whole genome sequencing (WGS)-only model for R27 paediatric genomic testing: South West genomic laboratory hub (SWGLH) experience to date

With the increased demand for genomic testing within the NHS Genomic Medicine Service (GMS), we need to utilise the most cost-effective technologies, analysis and reporting pathways. For many clinical indications (including paediatric disorders), WGS is the most comprehensive test available – allowing a wide range of genes to be analysed simultaneously and detecting a range of variant types with higher resolution and sensitivity compared to microarray. In January 2025, SWGLH moved to a new testing pathway for the R27/R29 Paediatric disorder clinical indications, for all patients presenting with moderate+ intellectual disability or syndromic developmental disease, utilising WGS as a ‘one stop’ mainstreamed test available to paediatricians. Since January, data shows a reduction of over 100 array cases tested per month. Case numbers for R27/R29 WGS increased by ~35 WGS cases a month. The R27 WGS diagnostic yield remained consistent; 32% 2023/2024 vs 29% 2024/2025, indicating that referral specificity has been maintained despite an overall reduction in test numbers We present a pathway overview and our experience to date, including the clinician engagement strategy, analyst training and audit data. The utility of this testing strategy is demonstrated using cases examples.