MSUD patients exhibit a failure to thrive and neurological deterioration thought to be associated with the accumulation of BCKAs.24 This was mirrored in a different, previously published mouse line with an ENU-induced Bcat2, which resulted in the 5′ splice site in Bcat2 and the deletion of exon 2 with an absence of mature BCAT2 protein.28 These mutant mice displayed failure to thrive, reduced body weight and early death; no details were provided on the early death phenotype, and cardiac (electrophysiological) characterization was not performed. This evidence concerns the gene BCAT2 and Failure to thrive.