PLOD1 and Delayed puberty: Ten patients with delayed puberty exhibited reduced testicular volume (2.6 ± 0.5 ml), low basal LH levels [0.23 (0.15–0.24) IU/L] and reduced testosterone production [< 0.35 nmol/L in all but one patient (P34, 0.62 nmol/L)] at 14.1 years of age (range: 14.0–15.3), suggesting the presence of HH.