Hereditary disease and its control.
Authors: P R Evans
Journal: BMJ (1975)

Today when accidents and malignant disease are being tackled with some success increasing interest is being shown in hereditary disease-that is, disease which may be passed from parents to children through reproductive cells.Tay-Sachs Disease Waren Tay was born in 1843; he qualified in medicine at the London Hospital and was appointed to it as a surgeon.He was also on the staff of the Royal London Ophthalmic Hospital at Moorfields and City Road, and the North East Hospital for Children, which became Queen Elizabeth Hospital, Hackney Road.A versatile man, he was also dermatologist to the Hospital for Diseases of the Skin.In 1881 he reported his findings in the eyes of a 1-year-old child with severe muscular weakness.Six years later, in 1887, Bernard Sachs gave a detailed clinical and pathological account of the disease and gave the name "cherry red spot" to the macular changes.He recognized that the condition was hereditary and occurred in Jewish babies and called it amaurotic family idiocy.He was born in Baltimore in 1858 to German immigrant parents and after studying at Harvard and Strasburg he became a leading neurologist in New York, and in 1905 wrote the first American book on paediatric neurol- ogy.He lived on into the penicillin era and died in 1944.Tay-Sachs disease is characteristically commoner among *Based on the Tay-Sachs Foundation Lecture delivered at the Institute of Child Health on 2 December 1974.Ashkenazi Jews than among Sephardic or any other Jews.It must have originated after, perhaps long after, the diaspora which followed the conquest of Jerusalem by Titus during the first century A.D. Historical evidence shows that Jews in east Europe did not often marry with gentile neighbours or members of other Jewish communities but remained isolated.In such a Tay-Sachs community the affected babies would die but the carriers would survive, and if they had a slight selective advantage in fertility they would increase in numbers.Myrianthopoulos and Aronson' suggest that this is the case, and that some immunity to tuberculosis is a possibility and an important one in crowded mediaeval towns.It was calculated from the incidence of cases that 1 in 30 Ashkenazis would be carriers, compared with 1 in 300 in other populations.Now that carriers can be identified by blood tests the figures for the Ashkenazis have changed to, for example, 1 in 23 in Baltimore, Washington, and London and as high as 1 in 14 in Toronto.Presumably the Baltic Jews who went to Toronto included many who came from one particular region with a high carrier rate and were not much diluted by inunigrants from other places.This instance of the relationship between a hereditary disease and a group of people stands out becaue ofits rather homogeneous nature, but the disease is not limited to Jews.The disease and its cause, deficient enzyme hexosaminidase A, seem to be the same in Jews and non-Jews.Mental defect due to phenylketonuria (P.K.U.) is uncommon in Jews; it is commoner in Celts in Ireland and west Scotland.Saugstad3 has shown that P.K.U.patients in Norway as a group do not have the pattern of blood groups characteristic of Norwegians but a pattern characteristic of the Irish and Scots; she says that Scots immigrated to Norway 1000 years ago and they brought the P.K.U.inheritance.P.K.U. is also common in Poles; did some of the migrating Scots move up the Baltic?It would be interesting to find out the blood groups of P.K.U.Poles and compare them with the usual distribution in Poland.Dr. C. 0. Carter, having calculated mutation rate and the effects of inheritance, thinks that the relevant migration may have occurred earlier, not long after the ice age ended in Norway.