An isolated monoclonal antibody or isolated monoclonal antibody fragment or antigen binding portion or fragment thereof, that binds human and/or mouse EDAR, said antibody comprising: (a) a heavy chain variable region comprising the complementary determining region amino acid sequences: SEQ ID NO: 1, SEQ ID NO: 2, and SEQ ID NO: 3; and a light chain variable region comprising the complementary determining region amino acid sequences of SEQ ID NO: 4, SEQ ID NO: 5, and SEQ ID NO: 6; (b) a heavy chain variable region comprising the complementary determining region amino acid sequences of SEQ ID NO: 7, SEQ ID NO: 8, and SEQ ID NO: 9; and a light chain variable region comprising the complementary determining region amino acid sequences of SEQ ID NO: 10, SEQ ID NO: 11, and SEQ ID NO: 12; (c) a heavy chain variable region comprising the complementary determining region amino acid sequences of SEQ ID NO: 13, SEQ ID NO: 14, and SEQ ID NO: 15; and a light chain variable region comprising the complementary determining region amino acid sequences of SEQ ID NO: 16, SEQ ID NO: 17, and SEQ ID NO: 18; (d) a heavy chain variable region comprising the complementary determining region amino acid sequences of SEQ ID NO: 19, SEQ ID NO: 20, and SEQ ID NO: 21; and a light chain variable region comprising the complementary determining region amino acid sequences of SEQ ID NO: 22, SEQ ID NO: 23, and SEQ ID NO: 24; or (e) a heavy chain variable region comprising the complementary determining region amino acid sequences of SEQ ID NO: 25, SEQ ID NO: 26, and SEQ ID NO: 27; and a light chain variable region comprising the complementary determining region amino acid sequences of SEQ ID NO: 28, SEQ ID NO: 29, and SEQ ID NO: 30; for use in the treatment of an ectodermal dysplasia wherein the antibody, antibody fragment, or antigen binding portion, or fragment is multivalent. (a) a heavy chain variable region comprising the complementary determining region amino acid sequences: SEQ ID NO: 1, SEQ ID NO: 2, and SEQ ID NO: 3; and a light chain variable region comprising the complementary determining region amino acid sequences of SEQ ID NO: 4, SEQ ID NO: 5, and SEQ ID NO: 6; (b) a heavy chain variable region comprising the complementary determining region amino acid sequences of SEQ ID NO: 7, SEQ ID NO: 8, and SEQ ID NO: 9; and a light chain variable region comprising the complementary determining region amino acid sequences of SEQ ID NO: 10, SEQ ID NO: 11, and SEQ ID NO: 12; (c) a heavy chain variable region comprising the complementary determining region amino acid sequences of SEQ ID NO: 13, SEQ ID NO: 14, and SEQ ID NO: 15; and a light chain variable region comprising the complementary determining region amino acid sequences of SEQ ID NO: 16, SEQ ID NO: 17, and SEQ ID NO: 18; (d) a heavy chain variable region comprising the complementary determining region amino acid sequences of SEQ ID NO: 19, SEQ ID NO: 20, and SEQ ID NO: 21; and a light chain variable region comprising the complementary determining region amino acid sequences of SEQ ID NO: 22, SEQ ID NO: 23, and SEQ ID NO: 24; or (e) a heavy chain variable region comprising the complementary determining region amino acid sequences of SEQ ID NO: 25, SEQ ID NO: 26, and SEQ ID NO: 27; and a light chain variable region comprising the complementary determining region amino acid sequences of SEQ ID NO: 28, SEQ ID NO: 29, and SEQ ID NO: 30;