MONDO_0005520 (rickets) is bone softening and weakening usually caused by deficiency or impaired metabolism of vitamin D. Deficiency of calcium, magnesium, or phosphorus may also cause rickets. It predominantly affects children who suffer from severe malnutrition. It manifests with bone pain, fractures, muscle weakness, and skeletal deformities. Also known as: rachitis, rickets (disease), vitamin D hydroxylation-deficient rickets.