Possible case of Rubinstein-Taybi syndrome in a prehistoric skeleton from west-central Illinois.

I describe an adult female skeleton (#Yo3-96) from the Yokem Mound skeletal series that had microcephaly; mild micrognathia; a broad nasal bridge; orbital hypertelorism; hypoplasia of the first metacarpals; pes planus; anomalies of the cervical spine, ribs, and sternum; and delayed epiphyseal remodeling of the radii and tibiae. Because the Yokem series has been subject to extensive measurement in previous studies, Yo3-96 can be characterized metrically and compared with others from her population. A differential diagnosis is made by comparing the available skeletal evidence with the known syndromes characterized by radial ray dysplasia. It is suggested that Yo3-96 represents the earliest known case of Rubinstein-Taybi syndrome, a mental retardation syndrome that has been described in individuals from several modern populations.