Exactly. This disease appears literally almost exclusively in the FLDS sect, and has been devastating. Incest and closed intermarriaged are the only reasons, since it is a recessive gene.
Would be interesting if they have done (or could do) a pedigree research to see if they could pinpoint the original carrier. One of my breeds of dogs has a lethal recessive gene in the gene pool and they had an expert go back and find the probably original carrier.
susie