Huntington’s disease (HD) is a rare and fatal brain disorder caused by a genetic mutation, an abnormal expansion of a repeating DNA sequence in the HTT gene on chromosome 4. HD is autosomal dominant, which means that each child of an affected parent has a 50% chance of inheriting the mutation. At-risk individuals may undergo predictive genetic testing to learn their carrier status before symptoms appear. The hereditary nature of the disease is central to Noah’s story; after his mother is diagnosed, he tests positive and must confront the certainty of his own health’s decline.

Symptoms typically emerge between ages 30 and 50 across motor, cognitive, and psychiatric domains. Chorea, involuntary jerking and writhing, is the hallmark motor symptom. Cognitive deterioration impairs reasoning and judgment, and psychiatric changes including depression, irritability, and impulsivity often appear earliest. Noah characterizes the condition as “a combo of ALS, Alzheimer’s, and Parkinson’s” (190), a description that conveys its scope. His mother’s presentation, including involuntary rocking, impaired speech, and uncontrolled facial movements, illustrates the disease’s middle stages. After symptoms appear, patients typically live another 10 to 30 years. Most ultimately die from complications related to swallowing, which the disease progressively impairs; aspiration pneumonia, caused by food or liquid entering the lungs, is the most common cause of death.

No cure currently exists. Tetrabenazine, a dopamine-reducing medication approved by the Food and Drug Administration in 2008, can manage chorea, and gene-silencing therapies remain under investigation, but no disease-modifying treatment has reached clinical use. Facing this prognosis, Noah plans to seek a physician-assisted death in Oregon, whose Death With Dignity Act (1997) was the first US law to permit terminally ill patients to request prescribed lethal medication under medical supervision.

Physician-assisted death, also known as medical aid in dying or physician-assisted suicide, remains ethically contentious, with advocates framing it as a matter of personal autonomy and critics raising concerns about the devaluation of life in the face of disability or suffering. The novel engages this tension directly. AJ initially opposes Noah’s plan, insisting that medicine will advance and that they can face the disease together. Noah, having witnessed his mother’s protracted decline, is unmoved: He views a controlled death as the last act of agency available to him. Over the course of the story, however, AJ’s presence challenges the premise of his plan. Noah doesn’t abandon his intention to die on his own terms, but he comes to accept that the years preceding that decision need not be lived in isolation. By the novel’s close, AJ pledges to support him “no matter what” (417), a promise that encompasses helping him when the time comes. An understanding of the medical reality of living with HD is crucial to the novel’s emotional stakes.