IGSF10 and Kallmann syndrome: To explore the possible role of mutations in IGSF10 in conditions of GnRH deficiency, we carried out targeted exome sequencing of IGSF10 in an adult cohort of 334 patients with HH due to Kallmann syndrome, idiopathic HH, or functional hypogonadism (hypothalamic amenorrhea (HA) or HA equivalent).