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A 23-year-old woman presented in a wheelchair because of progressive muscle weakness for 2 years and generalized bone pain. She lived in a rural area and was thought to have a psychiatric cause for her weakness and inability to walk. Elicitation of the patient's history disclosed no previous medical illnesses and no prior use of any medications. Physical examination revealed a young woman who was 153 cm tall, weighed 49 kg, and had generalized mild muscle tenderness, which was more pronounced in the right hip area. After beginning calcium and vitamin D supplementation, she was able to walk normally again, and a few months later, her serum calcium, phosphorus, and parathyroid hormone levels normalized.