Report of the Independent Expert on Minority Issues, A/HRC/13/23, 7 January 2010
IV. Minorities and effective political participation: a survey of law and national practices
D. Preconditions for and obstacles to effective political participation
56. Discrimination is a key cause of the widespread marginalization of minorities in societies worldwide. It is also an obstacle to the effective participation of minorities.
Discrimination can take different forms. Certain segments of minority populations are exposed to multiple forms of discrimination; in addition to being discriminated against on account of their belonging to a national or ethnic, religious or linguistic minority, they are discriminated against because of their gender, age, disability, sexual orientation or other grounds.
Link to full text of the report: http://www2.ohchr.org/english/bodies/hrcouncil/docs/13session/A-HRC-13-23.pdf