Yea, what a shame. Poor kid. The pahrunts obviously couldn't handle a retarded child. And that is fine - BUT - give the kid to a home from DAY 1 where he/she can be cared for by people who care. Don't keep the kid just because you feel obligated or guilty. These people have ruined that kid, I doubt very much will she ever be manageable by anyone else ever again.
My cousin and his wife adopted a 10 year old girl about a year ago. This child was used as a punching bag and sex toy for literally every member of the family - uncles, cousins, friends, everyone. She's got issues that will never go away. They are having one hell of a time with her. The problems are daily and severe. I don't know how they do it. And thanks to her "pahrunts," she will probably never be a productive member of society.