Since the restoration, the LDS Church has taught that certain dark skinned people were cursed to be cut off from the presence of the Lord:
20 Wherefore, the word of the Lord was fulfilled which he spake unto me, saying that: Inasmuch as they will not hearken unto thy words they shall be cut off from the presence of the Lord. And behold, they were cut off from his presence.
And that their darks skins were a sign of the curse so that they could be recognized as being cursed:
21 And he had caused the cursing to come upon them, yea, even a sore cursing, because of their iniquity. For behold, they had hardened their hearts against him, that they had become like unto a flint; wherefore, as they were white, and exceedingly fair and delightsome, that they might not be enticing unto my people the Lord God did cause a skin of blackness to come upon them.
22 And thus saith the Lord God: I will cause that they shall be loathsome unto thy people, save they shall repent of their iniquities.
23 And cursed shall be the seed of him that mixeth with their seed; for they shall be cursed even with the same cursing. And the Lord spake it, and it was done. (2 Nephi 5:21-23)
Today, the official stance of the church is this:
"Today, the Church disavows the theories advanced in the past that black skin is a sign of divine disfavor or curse, or that it reflects unrighteous actions in a premortal life; that mixed-race marriages are a sin; or that blacks or people of any other race or ethnicity are inferior in any way to anyone else. Church leaders today unequivocally condemn all racism, past and present, in any form." (Race and the Priesthood)
Does this mean that the Church is disavowing that people of African descent were ever cursed and bore the sign of the curse? Or does this mean that since the curse was lifted, and in 1978 when the Preisthood was officially offered to all worthy males, that the "sign of the curse" was no longer a sign of anything except mortal heritage, and that those spirits being born with those phenotypes today are no longer born to those lines based on premortal favour?