Carpenter Syndrome is described as a unique set of similar physical characteristics which were first noticed in the early 1900's by British physician, George Carpenter. He described two sisters and a brother with acrocephaly (cone shaped heads), peculiar facies, brachydactyly (abnormally short fingers), syndactyly (webbing) of the fingers and toes, and polydactyly (extra digits).
Although a test has finally been developed, it is often still identified in much the same way, with a genetics specialist making the diagnosis based upon their personal observations of the physical manifestations.
With less than 100 documented cases, Carpenter Syndrome is one of the rarest forms of the craniofacial disorders. While there are some significant differences, a good point of reference is it's similarity to Pfeiffer and Apert Syndromes.