Caudal Regression Syndrome (CRS), also known as caudal agenesis or sacral agenesis, is a rare congenital disorder characterized by abnormal development of the lower (caudal) portion of the spine. This condition typically involves the partial or complete absence of the sacrum and coccyx, and in severe cases, may also affect the lumbar spine. CRS is often associated with a range of additional anomalies, including spinal cord malformations, genitourinary abnormalities, gastrointestinal defects, and lower limb deformities. The severity of the syndrome can vary widely, from mild cases with minimal symptoms to severe cases that may result in significant physical disabilities.

The exact etiology of CRS remains unclear, but it is believed to result from a combination of genetic and environmental factors. Maternal diabetes mellitus has been identified as a significant risk factor, though cases have also been reported in non-diabetic mothers. Diagnosis is typically made through prenatal imaging, such as ultrasound or MRI, or shortly after birth based on physical examination and radiographic findings