Kallmann syndrome
![](/Images/godic/202501/22/GNRH1_structure0641.png")
![Figure 5 shows the normal hormonal control of puberty from the hypothalamus down to the testes or ovaries and their negative feedback mechanisms. The negative feedback control allows just the right amount of hormone to be released according to the needs of the body at that time.](/Images/godic/202501/22/Flow_diagram_showing_normal_hormonal_control_of_puberty0641.gif")
![Figure 7 shows the effect of the interruption of GnRH hormone release from the hypothalamus on the subsequent inability of the testes and ovaries to function correctly at puberty as seen in cases of KS/HH. In most cases of KS/HH the testes and ovaries are able to function correctly, but fail to do so because they have not had the correct hormonal signals.](/Images/godic/202501/22/Diagram_showing_the_disruption_of_the_hormonal_pathways_of_puberty_due_to_the_failure_of_GnRH_release_seen_in_KS_and_HH0641.gif")
Kallmann syndrome is a genetic condition where the primary symptom is a failure to start puberty or a failure to fully complete it. It occurs in both males and females and has the additional symptoms of hypogonadism and almost invariably infertility. Kallmann syndrome also features the additional symptom of an altered sense of smell; either completely absent (anosmia) or highly reduced (hyposmia). Kallmann syndrome occurs when the hypothalamic neurons that are responsible for releasing gonadotropin-releasing hormone (GnRH neurons) fail to migrate into the hypothalamus during embryonic development.