Ethical issues in genomic diagnosis and cascade testing

A 4-year-old boy with global developmental delay, mild dysmorphism, and a family history of a maternal aunt with early-onset breast cancer undergoes trio exome sequencing after a non-diagnostic chromosomal microarray. The exome returns a variant of uncertain significance in a gene plausibly related to his phenotype, a confirmed pathogenic variant in a hereditary cancer gene as a secondary finding, and establishes that the boy's developmental variant was inherited from his unaffected mother. The case walks the candidate through the classification of each finding by its ethical demand, the consent pathway that should have preceded testing, the disclosure of the VUS (investigate and re-analyse, never act), the management of the secondary finding (opt-in consent), and the cascade-testing implications for the mother, her siblings, and the maternal aunt — all anchored in the child's best interests, documented consent, and the right to an open future.