Multifocal anaplastic astrocytoma in a patient with hereditary colorectal cancer, transcobalamin II deficiency, agenesis of the corpus callosum, mental retardation, and inherited PMS2 mutation.

We describe the case of a patient with transcobalamin II deficiency, hypogammaglobulinemia, absent corpus callosum, and mental retardation who presented at an early age with colorectal cancer and multifocal anaplastic astrocytoma. He was found to have a possible germline mutation of the PMS2 gene, as evidenced by absent protein expression in both normal and tumor tissues. His parents were found to be carriers of a nonsense mutation of the PMS2 gene.