SPRY4 and Infertility: Our RNA profiling data strongly support the theory that in the high infertility risk group of cryptorchid boys insufficient PROK2/CHD7/FGFR1/SPRY4 gene expression, together with observed deficient EGR4 and PITX1 signaling, induce deficient LH secretion, which results in impaired mini-puberty [28, 44, 105, 108, 109].