MEIG1, a murine gene first identified as a testis specific gene, is a chromosome/chromatin-binding protein initially expressed during meiosis but retained in the germ cell nucleus throughout later stages of spermatogenesis. MEIG1 is a highly conserved basal metazoan gene that is indispensable for mouse spermatogenesis. It is important for normal meiotic differentiation and absolutely crucial for terminal differentiation of spermatozoa. MEIG1 encodes two alternative transcripts, designated 2a2 and 11a2, both of which encode for a common ORF but differing in their 5′ untranslated region (5′UTR) due to alternative promoters.