Opportunistic genomic screening of healthy controls in an Australian biobank.

Leveraging existing genomic data to opportunistically screen for secondary findings (SFs) can identify individuals at increased genetic risk who may be missed by criteria-based testing. While some guidelines support returning actionable SFs with professional support, there is a gap in consistent practice regarding the return process. This study reports the outcomes of opportunistic genomic screening in an Australian biobank. Whole genome sequencing data from 1057 healthy participants in the Tasmanian Ophthalmic Biobank (TOB), all of white European ancestry, underwent opportunistic screening for pathogenic (P) or likely pathogenic (LP) variants affecting genes in the ACMG SF v3.0 list. Variants of interest were manually curated, and only P/LP variants were returned. Actionable SFs (P/LP variants) were identified in 3.6% (38/1057) of participants. The most common genes were HFE (haemochromatosis), LDLR (Familial Hypercholesterolemia), and TP53 (Li-Fraumeni syndrome). Of the 38 participants with a variant, 27 received their result, with two-thirds being newly informed. Ten participants were referred to clinical genetics for diagnostic confirmation, while seven declined to proceed. Opportunistic screening identified a clinically significant incidence of actionable SFs in a healthy biobank cohort. There was high participant interest in receiving results, although subsequent uptake of clinical referral remains a challenge.