Prenatal testing for variants in genes associated with hereditary cancer risk: laboratory experience and considerations.

Prenatal molecular genetic testing for familial variants that cause inherited disorders has been performed for decades and is accepted as standard of care. However, the spectrum of genes considered for prenatal testing is expanding due to genetic testing for hereditary cancer risk (HCR) and inclusion of conditions with associated cancer risk in carrier screening panels. A few of these disorders, such as ataxia telangiectasia and Bloom syndrome, include increased cancer risk as part of the phenotype, already meet professional guidelines for prenatal testing, and may be associated with increased cancer risk in heterozygous carriers. Additionally, recent studies implicate heterozygosity for variants in lysosomal storage disease (LSD) genes in HCR etiology. Currently, there is no specific professional guidance regarding prenatal testing for HCR. In order to determine the prevalence of such testing we reviewed 1345 consecutive prenatal specimens received in our laboratory for familial variant specific testing and identified 65 (4.8%) with a known or likely HCR component, plus 210 (15.6%) for LSD. These specimens were classified into five distinct categories for clarity and to enable evaluation. Our experience assessing prenatal specimens for variants associated with HCR, with or without a constitutional phenotype, provides metrics for and contributes to the points to consider in prenatal testing for HCR.