Long-read read genomic technologies are strongly emerging. These include mapping technologies such as optical genome mapping (OGM), but also long-read sequencing (LRS) technologies, such as PacBio HiFi genome sequencing.
LRS allow to assess the full human genome for the first time and have the potential to revolutionize human genetics. This technology could offer a comprehensive first-tier test for clinical genetics and rare disease research. To determine the clinical utility of LRS, we performed Revio HiFi genome sequencing on 1,500 human genomes with ~30-fold coverage, including 100 mutation-positive controls that are impossible or challenging to identify by standard short-read genome sequencing, 100 severe sporadic rare disease cases as patient-parent trios, and 100 severe rare disease cases as singletons who remained undiagnosed after standard-of-care testing. Finally, we run a prospective clinical utility study of 1,000 samples representing the annual germline testing of our diagnostic division.
These studies suggest LRS could serve as a first tier generic test across many rare disease, and as such replace almost all standard-of-care assay for germline testing. In addition, LRS suggests an additional yield between 10-20% by previously hidden variants in several rare disease studies.
Recurrent 600kb-long genomic rearrangements at 16p11.2 BP4-5 represent one of the most common causes of genomic disorders. They are mediated by human-specific duplications that appeared at the beginning of the modern human lineage, suggesting that their expansion has a possible evolutionary advantage that outweighs chromosomal instability.
These copy number variants (CNVs) are among the most frequent genetic causes of neurodevelopmental and psychiatric disorders, as they are found in 1% of individuals with autism spectrum disorders and schizophrenia. They were also originally associated with reciprocal defects in head size and body weight, but have since been associated with a plethora of phenotypic alterations, albeit with high variability in expressivity and incomplete penetrance. Revealing the complex and variable clinical manifestations of these CNVs is crucial for accurate diagnosis and personalized treatment strategies for carriers.
The 16p11.2 BP4-5 CNVs showcase variable expressivity and pleiotropy, as they are deleterious enough to be enriched in clinical cohorts but not enough so to be absent from population cohorts.