Initial investigations revealed severe hypocalcemia (serum calcium: 4.7 mg/dL, normal reference range (N): 8.4‐10.2 mg/dL), hyperphosphatemia (serum phosphate: 6.9 mg/dL, N: 2.7‐4.7 mg/dL), slightly low magnesium level (1.3 mg/dL, N: 1.7-2.3 mg/dL), high PTH levels (230 pg/mL, N: 15‐65 pg/mL), and VDD (25‐hydroxyvitamin D 13.7 ng/mL, N: 30‐100 ng/mL). The gene discussed is PTH; the disease is hyperphosphatemia.