I am interested in peripheral markers in Bipolar Personality Disorder patients.

I am not sure what you mean by "peripheral", but my first thought was scarring from self-inflected cuts and suicide attempts. Two relevent articles might be:
Biologic markers in borderline personality disorder: a review
HW Lahmeyer, CF Reynolds III, DJ Kupfer, R King - J Clin Psychiatry, 1989
and
Biological markers in borderline personality disorder: New perspectives
M Korzekwa, P Links, M Steiner - Canadian Journal of Psychiatry, 1993

I have not heard of minor physical anomolies in BPD such as those found in schizophrenic patients. - Jack

There is no such disorder as "Bipolar" Personality Disorder. Do you mean Borderline Personality Disorder? There is an Axis II disorder called Cyclothymic Personality Disorder, which has many features of bipolarity.- Jack

It was my mistake... obviously I was talking about borderline personality disorder. I don't know to what I was thinking and I must apologize.
About the word peripheral markers I was thinking to biological markers such as blood, CSF, blood and skin cells, and so on.
Thanks.