EIF2S3 and trisomy X: Since the protein sequence of mouse Eif2s3y is highly conserved (over 97% similarity) with those of mouse Eif2s3x and human X-linked EIF2S3, and there is no Y-linked homolog of Eif2s3y in humans (Supplementary Figures 7A,B), overexpression of Eif2s3y in male and female mice may partially resemble patients with Klinefelter Syndrome (47,XXY) and XXX Syndrome (47,XXX), respectively.