If one identical twin is diagnosed as schizophrenic is there a high probability that the other twin will also have a mental disturbance?

Most of this information is from a website (linked below) and a book that I had at home on psychology. The book details are listed below aswell.

According to the genetic model, there is evidence to suggest that there is a hereditary element to schizophrenia/panic disorders. If an identical twin has schizophrenia or rather displays the symptoms thereof, it is very likely that the other twin can also display the same symptoms.

Schizophrenia is also often mistaken as depression and therefore incorrectly treated. In order to diagnose schizophrenia and or other mental disorders etc. clinicians can use what is called the DSM-IV (Diagnostic and Statistical Manual, and IV being the roman numerals for the number 4). Although I would like to mention here that this is a western scale and might not be able to accurately diagnose a person from a non-western country.

Book details:

Martin, G., Carlson, N., & Buskist, W. (2007). Psychology (3rd ed.). Abnormal Psychology, Harlow: Pearson Education