What are HNPP and MCTD? // My Disabilities What are HNPP and MCTD? // My Disabilities Another fascinating video from Jessica Kellgren-Hayes. Do check out her introduction to brain fog here. In this video she tells us about her disabilities Hereditary Neuropathy with Pressure Palsies (HNPP) and Mixed Connective Tissue Disease (MCTD), and what it’s like living with them.