“…Thus, the domain is a mutation hot spot, where the COMP mutation we identified was located. In addition to a large number of missense mutations, it also includes in-frame small deletions, insertions, or indels [ 12 , 26 , 27 ]. Three COMP mutations (c.1315G>A, p.D439N; c.13169r, p.D439G; c.1317C>A, p.D439E) were identified in MED cases, which altered the 439 th amino acid (AA) of COMP[ 20 , 28 , 29 ].…”