Over the last 2 years there have been very exciting developments in the understanding of the genetic basis of delayed puberty, particularly with respect to the transcriptional and epigenetic control of the GnRH “master switch.” We anticipate further discoveries in the near future that will help to elucidate these control mechanisms and better understand the genetic predisposition to familial delayed puberty and to conditions of functional hypogonadism. Here, GNRH1 is linked to hypogonadism.