Monogenic diseases aren’t deterministic: context shapes genetic risk

New population-genomics research shows that many so-called monogenic diseases do not have 100% penetrance; a person carrying a disease-associated variant may remain healthy depending on other genetic factors and environment. Large datasets reveal that variants once believed to almost always cause conditions like inherited retinal degenerations, thyroid cancer, ovarian insufficiency, and even Huntington's disease do not guarantee disease in the general population, highlighting the need for nuanced genetic counseling and individualized risk assessments and potentially informing advances in gene therapies and embryo selection.