For example, TBX1 dysregulation is linked to 22q11.2 deletion syndrome,8TBX3 to ulnar-mammary syndrome,9TBX4 to stiff-person syndrome (SPS)10 and developmental dysplasia of the hip (DDH),11 and TBX5 to Holt-Oram syndrome.12 The gene discussed is TBX1; the disease is stiff-person syndrome.