[David O. McKay]
You ask whether a person having negro blood in his or hr veins might receive a blessing from a Patriarch. The answer is Yes. A Patriarch may pronounce upon anybody's head the blessing to which that person may be entitled. The privileges, as you know, thus far accorded to negroes are limit in the Church of Jesus Christ of Latter-day Saints.
[David O. McKay, Letter to Henry H. Hoff, as quoted in Minutes of the Apostles of The Church of Jesus Christ of Latter-day Saints, 1910-1951, Privately Published, Salt Lake City, Utah 2010]