The clinical entity of mongolism was described by Down1 in 1866. The disease is characterized by mental retardation and somatic changes involving many parts of the skeleton. The typical appearance of the head and face is probably due not to an atavistic reversion to mongolian features but rather to an abnormal underdevelopment of the bony structures at the base of the skull (Benda1a). Other anomalies found in persons with mongolism are undersized stature, slanting eyes, small and flattened nose, small and poorly shaped ears, thick lips, scrotal tongue, delay in dentition, lax joints, congenital heart disease and occasionally other signs of maldevelopment.
A peculiarity in the shape of the hand of mongolian imbeciles was described first by Smith2 in 1896. He called attention to a marked outward bowing or curve of the little finger. A roentgenogram demonstrated for the first time the reason for his clinical impression.
HEFKE HW. ROENTGENOLOGIC STUDY OF ANOMALIES OF THE HANDS IN ONE HUNDRED CASES OF MONGOLISM. Am J Dis Child. 1940;60(6):1319-1323. doi:10.1001/archpedi.1940.02000060077008