Yes, but Huntington's is an explicit cluster of symptoms at diagnosis + a specific prognosis. Uppercase D "Depression" is a diagnosis built around a single symp

Yes, but Huntington's is an explicit cluster of symptoms at diagnosis + a specific prognosis. Uppercase D "Depression" is a diagnosis built around a single symptom, lowercase d "depression". But many people experience depression, both in "core mental illnesses" like bipolar and outside. (Note how bipolar is much better constructed -- indeed the method of differential diagnosis was invented by Kraepelin to differentiate bipolar from schizophrenia) If it was up to me, big D Depression would be redefined as "responds to Prozac" or something.