PLOD1 and cartilage-hair hypoplasia: To differentiate between CHH and CDGP, the study of LH nocturnal pulses has been proposed: in fact, the lack of nocturnal LH pulses in adolescence was described to be specific for HH, but a similar pulsatile fluctuation was found in prepubertal children and patients with CDGP and CHH by using ultrasensitive assays [28].