Selective chr21 homolog silencing reveals polymorphisms influence the epigenetic silencing and functional dosage of RWDD2B

Selective homolog silencing (with XIST) provides an approach to study polymorphisms in cells from one individual, complementing population-level studies. In trisomy 21 iPSCs, primarily only one specific homolog transcribed RWDD2B, which is linked to polymorphisms impacting promoter methylation. Uncoupling transcription from copy number has implications for Down syndrome and the general population.