For infant control and CDM samples, RNA-seq libraries were prepared using the SMART-Seq version 4 ultralow input RNA kit (Clontech) per the manufacturer's instructions and sequenced using an Illumina HiSeq 2000. For PolyA-seq libraries, total RNA (130 ng) was used as a starting template, and libraries were generated as described (Batra et al. 2014 (link)) with the modification of adding barcodes to the library amplification primers to accommodate multiplex sequencing. For mouse P0 muscle and primary myoblast samples, RNA was isolated using the Direct-Zol RNA miniprep kit (Zymo Research). RNA-seq libraries were prepared from total RNA (500–700 ng) using the stranded RNA-seq kit with RiboErase (Kapa Biosystems) per the manufacturer's protocol. The CDM PolyA-seq and all mouse libraries were sequenced using an Illumina NextSeq 500.