The amount of a phosphatidylinositol-3,4,5-trisphosphate 5-phosphatase 1 when measured in blood serum. The trait is level of phosphatidylinositol-3,4,5-trisphosphate 5-phosphatase 1 in blood serum (OBA_2040434). Also known as: blood serum phosphatidylinositol-3,4,5-trisphosphate 5-phosphatase 1 amount.