Type 1 albinism is caused by defects that affect production of the pigment, melanin.
Type 2 albinism is due to a defect in the "P" gene. People with this type have slight coloring at birth. Since there is obviously an actual genetic change that is more common place among the Hopi and Zuni or Pueblo Nations the question arises as to why? or How?
The Book of Mormon speaks of possible genetic changes that took place mainly upon the Lamanites. In 2 Nephi 5 Jacob shares some information about the curse that took place as the Nephites seperated themselves from the Lamanites. He says, speaking about the Lords treatment of the Lamanites, "and he caused a cursing to come upon them, yeah, 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." He later states that, "they did become an idle people" It seems as though the curse was to not be in the presence of the spirit of the Lord it didn't actually effect the skin color. There is a difference between the mark and the curse. The mark placed upon the Lamanites was a dark skin (Alma 3:6). The curse was not the dark skin but being "cut off from the presence of the Lord" (2 Nephi 5:20). Notice that in both Alma 3:7 and Alma 3:14 the conjunction "and" is used between the curse and the mark. This implies that they are not the same thing. The people brought the curse upon themselves: "And even so doth every man that is cursed bring upon himself his own condemnation" (Alma 3:19) Through righteousness the curse may be removed, but the mark may remain as it has with the Lamanites. It the case of repentence there were many times where the mark may have had a reverse effect keeping the righteous Lamanites from mingling with wicked Nephites.