There are multiple definitions:

1. major histocompatibility complex(English)

   • a highly polymorphic region of the genome that encodes MHC cell surface proteins that display, or present, peptides derived from protein antigens
   • APC, DC, CTL, pMHC
   • Immunology
   • https://doi.org…science.1142955
   • https://doi.org…isb.2020.10.010

2. myosin heavy chain(English)

   • HCM, MLC
   • Physiology, Myocyte / muscle

3. mental health component(English)

   • COVID-19, ENO, PHC, VAS
   • Mental health
   • https://www.eno.org/breathe/

4. mechanosensory hair cell(English)

   • EGT, hWJC, MCET, SNHL
   • Auditory system
   • https://doi.org…al.pone.0245234