TB vulnerability in our genes
The dramatic decrease in the number of deaths from tuberculosis which has occurred in this century is unfortunately not matched by a comparable fall in the number of people who contract the disease. Thus, in spite of highly effective new methods of treatment by means of drugs and surgery, tuberculosis remains a major medical problem, with 50 million cases in the world each year.
However, now that treatments are available to counter this disease and many people recover from it, it is becoming apparent that there is an important factor affecting the incidence of tuberculosis and its severity in different individuals, including their ability to fight the disease. It is clear that this factor is genetic, and passed down from generation to generation. A study by Dr J. F. Kallmann, who has traced the medical history of large numbers of twins in New York, has provided definite evidence that the course taken by the disease after infection is almost completely determined by heredity. When the twins came from a single egg 鈥� that is, they were genetically identical 鈥� the disease always took the same course in both patients. Especially, it was rare for one twin to survive the disease if the other did not. That these similarities were not due to identical environments was proved by the fact that twins from two eggs (and therefore not genetically identical) did not show the same concordance, although they were just as likely to have shared similar environments as genetically identical twins.
Advertisement
Genetic factors may be important in other infectious, deadly diseases too but, as in the case of tuberculosis, they only become apparent when effective methods of treatment allow enough people to survive to make it possible to recognise differences in response.
From The New 杏吧原创, 20 June 1957