<unk>  is a diagnosis which only appeared in the revised third edition of the American Psychiatric Association's Diagnostic and Statistical Manual of Mental Disorders (DSM-III-R). The current version of the DSM (DSM-IV-TR) does not include it, so it is no longer considered a valid diagnostic category.  There appears to be a genetic component to the disorder.
Sadistic personality disorder
Emotionally unstable personality disorder
Self-defeating personality disorder
Histrionic personality disorder
Dependent personality disorder
Avoidant personality disorder
Dissocial personality disorder
Paranoid personality disorder