DPYD and hyperparathyroidism: Since these observations represent three typical histological features of hyperparathyroidism (Parisien et al, 1990), and neonatal hyperparathyroidism has been occasionally reported in MLII patients (Unger et al, 2005), we determined serum concentrations of PTH together with the urinary concentrations of desoxypyridinoline (Dpd), a type I collagen degradation product, corresponding to crosslaps in mice (Fig 4F).