226AN ANATOMICAL STUDY OF LUMBOSACRAL TRANSITIONAL VERTEBRALumbosacral transitional vertebrae are congenital anomalies of the lumbosacral region which include sacralisation of fifth lumbar vertebrae and lumbarization of first sacral vertebrae. Lumbarization occurs when the uppermost segment of the sacrum is not fused to the rest of the sacrum but instead it is partially mobile constituting an 'extra' lumbar vertebra, often referred to as L6. Sacralization is described as having one fewer lumbar vertebra because the last lumbar segment (L5) is fused to the sacrum. Material and Methods: A study was conducted in the Department of Anatomy of K. J. Somaiya Medical College in which hundred adult dry human sacra were examined to study the incidence of lumbarisation and sacralisation. Results: 28% specimens showed anatomical anomalies of lumbosacral transitional vertebras out of which 16% showed anomalies of lumbarisation and 12% showed anomalies of sacralisation. The specimens showing lumbarisation and sacralisation were studied in detail. Conclusions: Sacralization of L5 vertebra is more common than lumbarization. The incidence between these anomalies is 2:1. Mutations in the HOX 10 and HOX 11 paralogous genes affect the normal pattering of lumbar and sacral vertebra. The consequences of the sacralisation may be the degenerative spondylolisthesis, disc herniation, low back pain and disc degeneration. Identification of lumbosacral transitional vertebrae (LSTV) is crucial for precise resolution of the number of vertebrae.sharad@somaiya.eduResearch1112021Lumbosacral transitional vertebrae,Lumbarization,Sacralization,low back pain,Degenerative,Spondylolisthesis,Disc Degeneration,Disc HerniationDr. Shaheen Rizvi,Dr. Sharadkumar Pralhad SawantDepartment of Anatomy, K. J. Somaiya Medical College, Somaiya Ayurvihar, Eastern Express Highway, Sion, Mumbai-400 022, India,Professor and Head Maharashtra University of Health Sciences, Nashik, Maharashtra, India.