Genetic variants believed to cause blindness in nearly everyone who carries them actually lead to vision loss less than 30% of the time, new research finds.
The study challenges the concept of Mendelian diseases, or diseases and disorders attributed to a single genetic mutation. The idea is that Mendelian diseases — such as the neurological disease Huntington's and the bleeding disorder hemophilia — are passed down in predictable ways in families, and if a given person carries a disease-causing mutation, they will have it.
