In 2004, TBX4 was recognized as responsible for Small Patella Syndrome (SPS), also known as ischial-coxo-podo-patellar syndrome (ICPPS, MIM number 147,891), a spectrum of limb and skeletal abnormalities that results in developmental abnormalities of the foot and pelvis as well as patellar aplasia or hypoplasia [5]. Here, TBX4 is linked to coxopodopatellar syndrome.