TRAPPC2 and spondyloepiphyseal dysplasia tarda, X-linked: Moreover, 3 of the SEDLIN missense mutations (Ser73Leu, Phe83Ser and Val130Asp) and 1 nonsense mutation (Gln131Stop) located within the hydrophobic core and associated with SEDT in patients lead to a loss of interactions with the transcription factors MBP1, PITX1 and SF1.