I'm a perfectionist. Sometimes, when I don't reach my goal, I get really depressed. 
Is depression a common symptom of perfectionism?
Yes, it happens often. There's a lot of pressure and when we don't reach our goal, it's disappointing.
Can a person be cured from perfectionism?
Well, it's a form of OCD, so it could be tamed with help from a therapist or medication.
I see. Do a lot of people suffer from this disorder?
It's estimated that 1 in every 40 adult in the US has OCD. That's about 2.3 percent of the population, so yes, I believe there are a lot. 
That's more common than I thought. Are there any famous cases?
I assume there are a lot, since such a large number of the population is affected by perfectionism. 
How long has perfectionism been considered to be a serious mental condition by psychologists?
It's been a known condition since 1978, which was when D.E. Hamachek separated two different types of perfectionism: normal, or neurotic.