Grade 1 anterolisthesis refers to a condition where one vertebra slips forward over another by up to 25%. In the case of C7-T1 and T1-T2, it indicates that the C7 vertebra has moved slightly forward over T1, and T1 has similarly shifted forward over T2. This can result in potential nerve compression and may cause symptoms such as pain or neurological issues. Diagnosis and management typically involve imaging studies and may require conservative treatment or surgery depending on severity and symptoms.