Superior intelligence of children blinded from retinoblastoma.

It has been widely discussed amongst teachers of the blind that the children blinded from retinoblastoma are generally of above average intelligence. In an investigation into the intelligence of blind children, undertaken by the writer (1956), the IQ results obtained by this particular group of children suggested an above-average trend. The present investigation was therefore undertaken to study the intelligence of children at blind school whose blindness was due to retinoblastoma. A retinoblastoma is a malignant tumour of the eye, originating from immature retina cells. The incidence has been variously estimated as being from 1 in 21,000 to 1 in 34,000 live births. Boys and girls are usually affected in about equal numbers. Retinoblastoma may occur during fetal life and so be manifest at birth. In approximately 70% of cases the tumours are discovered before the age of 3, and in the majority of the rest before 6. In about 30% the tumours are bilateral, these being unconnected, independent foci of growth. The affected offspring of retinoblastoma survivors are particularly prone to bilateral tumours. That there is a hereditary factor in retinoblastoma is well recognized. Extensive work on this subject has been done by the Children's Tumour Registry and the Department of Ophthalmology in the University of Manchester; Dr. J. K. Steward writes: 'In our series there are 152 children in the Manchester region with proven retinoblastoma between 1900 and 1960. Of these, 101 were cured, and eight of these survivors have passed the disease to their progeny.' He further points out the impossibility of stating the proportion of patients without any antecedent family history of the disease but who would pass it on to their progeny, because if a survivor has only one or two children it cannot be said that his or her germ cells do not carry the