A Custom Global Screening Array for Integrated Familial Hypercholesterolemia Detection and Polygenic Risk Assessment in a Multi-Ethnic New Zealand Population
Background: Cardiovascular disease (CVD) is the leading cause of mortality in New Zealand, with significant inequities affecting M[a]ori and Pacific peoples. Familial hypercholesterolaemia (FH) affects approximately 1 in 313 individuals globally, yet over 90% remain undiagnosed. Standard polygenic risk scores (PRS) derived from European cohorts may not be portable to diverse ancestries. We developed the HoloQ Omniscan Waka Te Ira, a custom Illumina Global Screening Array (GSA) v3 enriched with FH mutations, coronary artery disease (CAD) PRS markers, and network medicine-derived content. Methods: We customised the GSA v3 by adding 43,437 single nucleotide polymorphisms (SNPs) targeting FH and CAD. Content included 6,717 unique variants in primary FH genes; 14,005 pathogenic or likely pathogenic cardiovascular and pharmacogene variants; and 5,845 copy number variant probes. We further incorporated 5,232 network medicine derived CAD SNPs, 14,806 rare variants for a multiancestry PRS, and 407 globally diverse and population-specific variants. The final design comprised 47,027 target SNPs. Validation utilised large-scale genotype and whole-genome sequencing (WGS) datasets with PRS benchmarking. Results: In a large European-ancestry dataset, we observed high recovery for common PRS loci but low recovery for population-specific founder variants. The array captured 938 (84%) of all pathogenic or likely pathogenic FH variants catalogued in ClinVar, representing a 26.4% expansion beyond the standard backbone array. WGS validation identified additional carriers of rare high impact variants present only in the custom content. The selected CAD PRS model achieved an adjusted area under the receiver operating characteristic curve of 0.786. Conclusion: The HoloQ Omniscan Waka Te Ira enhances detection of clinically relevant FH variants and provides robust PRS coverage. The low recovery of population-specific alleles underscores the necessity of this custom array for equitable genomic medicine in New Zealand's multi-ethnic population.