By Humeyra Pamuk WASHINGTON (Reuters) – Egypt has missed out on an additional $75 million in American military aid after a senior Democratic U.S. senator blocked the funding over concerns about Cairo’s human rights record including holding political prisoners. Senator Patrick Leahy, chairman of the Senate Appropriations Committee, rejected an assessment offered by the U.S. State Department to justify the aid, which was subject to conditions under a law passed by Congress last year. The committee has jurisdiction over spending legislation including U.S. financial assistance for Egypt. “We shoul…