The news release Monday morning grabbed my attention:
“Study finds wide gap in quality of BRCA1/2 variant
classification between Myriad Genetics and a common public database.”
Myriad Genetics had been exclusively providing tests, for
$3000+ a pop for full BRCA gene sequencing, for 17 years before the Supreme
Court invalidated key gene patents back in 2013. Since the ruling a dozen or so
competitors have been offering tests for much lower prices. Meanwhile, Myriad
has amassed a far deeper database than anyone else, having been in the business
so much longer. And it’s proprietary.
CLASSIFYING GENE VARIANTS
Public databases of variants of health-related genes have
been around for years too. The best known, ClinVar, collects and curates data
from the biomedical literature, expert panels, reports at meetings, testing
laboratories, and individual researchers, without access to Myriad’s database.
ClinVar uses several standard technical criteria to classify variants as
“pathogenic,” “benign,” or “of uncertain significance.” (“Likely pathogenic”
and “likely benign” were used more in the past.)
ClinVar lists 5400 variants just for BRCA1. The criteria
come from population statistics, how a particular mutation alters the encoded
protein, effects on the phenotype (symptoms), and other information.
Bioinformatics meets biochemistry to predict susceptibility. The BRCA1 protein
acts as a hub of sorts where many other proteins that control DNA repair
gather. DNA Science discussed the genes behind breast and ovarian cancers here.
As gene sequences accumulate in the databases and troops of
geneticists and genetic counselors annotate them, the proportion of pathogenic
and benign entries will increase as that of the unsettling “variants of
uncertain significance” — VUS — will decrease.
The views, opinions and positions expressed by these authors and blogs are theirs and do not necessarily represent that of the Bioethics Research Library and Kennedy Institute of Ethics or Georgetown University.