Although many readers (including me) will begin to read this book as a case study of HD, Genova has a particularly nice ear for dialog and local lingo and she tells an excellent story. Many parts of the book are funny or heartwarming and some, of course, are heart-rending.
Even if HD holds no special interest for you, one key plot issue (culminating in a gripping conclusion) is the 50-50 chance that a child of an HD patient has of inheriting the disease. Because HD is late onset, generally appearing only when a person is 40-50, the uncertainty of whether and when you will begin experiencing neurological symptoms is itself unnerving, even before any disease onset - this is powerfully depicted. There has been a genetic test for HD since the 1990's, but many at-risk people choose to live without taking the test. The all-or-nothing, 50-50 chance seems to throw into sharp contrast both the uncertainty of fate and the impossibility humans seem to have in evaluating how to make decisions in the absence of conclusive information. Very worthwhile read.
