Dear Editor,

Early ovarian expression of Newborn oogenesis homeobox (NOBOX), a transcription factor belonging to the homeoprotein class, is decisive for the progression of primordial follicles to the primary follicular stage as demonstrated by the sterility of Nobox−/− female mice (Rajkovic et al., 2004). Consequently, the loss of the Nobox gene causes primary ovarian insufficiency (POI) (Rajkovic et al., 2004) and we have shown that 6.2% of POI cases harbor mutations in the NOBOX gene (Qin et al., 2007; Bouilly et al., 2011). Such a high prevalence of mutations demonstrates that NOBOX is a major autosomal gene involved in POI (Bouilly et al., 2011). However, the exact role of this transcription factor during folliculogenesis is unclear.