Fundamentalist Church of Jesus Christ of Latter Day Saints

Overview
The Fundamentalist Church of Jesus Christ of Latter Day Saints (FCJCLDS) is a "breakaway sect" of (and no longer affiliated with) the Church of Jesus Christ of Latter-day Saints. They have member churches in a number of small towns in the US and Canada.

The FCJCLDS is known for having a high incidence of fumarase deficiency, a genetic disorder, due to intensive inbreeding.