Incidence of mongolism and its diagnosis in the newborn.

An accurate estimate of the incidence in the general population of mongolism at birth is required for the genetic study of the disease. Penrose (1949) has esti mated the frequency of the condition among children of school age in Great Britain from the records of local authorities; the incidence among children aged 10 to 14 is probably about 1 in 2,000. He stresses, however, that the high infant mortality of mongols implies that the incidence at birth is considerably higher than this. The only figure available for the incidence at birth in Great Britain is that given by Malpas (1937) for a maternity hospital; he found eighteen cases in 13,964 births, that is 1 in 776; but with such small numbers the random error may