Evaluation of LH pulsatility may help reduce this uncertainty, as patients with CHH have been shown to lack the sleep-entrained increase in LH pulse amplitude and number present in 75% of pre-pubertal children [11]; and in the small proportion of patients with CHH that have detectable pulsatile LH secretion (25% in one series of 78 men), the LH pulses are abnormal (i.e., low amplitude and/or low frequency) [12]. The gene discussed is PLOD1; the disease is cartilage-hair hypoplasia.