Langer-Giedion syndrome (LGS), also known as trichorhinophalangeal syndrome type II (TRPS II; OMIM #150230), is a contiguous-gene deletion disorder caused by haploinsufficiency of <i>TRPS1</i> and <i>EXT1</i>. The gene discussed is TRPS1; the disease is Langer-Giedion syndrome.