Thrombocytopenia 4, also known as thc4, is related to thrombocytopenia and contractures, pterygia, and spondylocarpotarsal fusion syndrome 1a. An important gene associated with Thrombocytopenia 4 is CYCS (Cytochrome C, Somatic). Affiliated tissues include bone marrow and bone, and related phenotypes are thrombocytopenia and abnormal platelet volume