HEREDITY AND TUBERCULOSIS 



A Review 



A GENERATION ago, it was al- 

 most universally supposed that 

 tuberculosis was due to heredity. 

 Then medical opinion was led astraw 

 and for some years the genetic factors 

 in the case were depreciated. During 

 the last decade a number of careful 

 studies have corrected this mistake, 

 until it is now clear that the inheri- 

 tance of lack of resistance is one of 

 the principal causes of death from con- 

 sumption. 



While in the United States last year, 

 Albert Govaerts, director of the Office 

 Beige d'Eugenique, made a study of 

 this subject at the Eugenics Record 

 Office, and his results have been pub- 

 lished as Bulletin No. 23 of that office.' 

 He reviews in a sketchy and inadequate 

 way some of the other studies of the 

 subject, notes the important work of 

 Sewall Wright and P. R. Lewis on 

 guinea pigs, and then publishes his own 

 contribution, which is an analysis of 

 family histories taken from the archives 

 of the Eugenics Record Office. 



The analogy of the breeding experi- 

 ments agrees very nicely with the con- 

 clusions that had previously been drawn 

 as to the inheritance of resistance to 

 tuberculosis in man. Tests made on 

 more than 100 guinea pigs belonging 

 to five closely inbred families show 

 marked differences in susceptibility 

 among the different families, and the 

 rank of the various families in respect 

 of resistance to tuberculosis bears no 

 relation to their rank in respect of the 

 various factors of general vigor. It is 

 thus clear that independent hereditary 

 factors are involved ; moreover, in par- 

 ticular crosses the average of the pro- 

 geny is consistently superior to either 

 parental line, indicating that the latter 

 are susceptible for different reasons, 



each being able to supply what the 

 other lacks. In general, resistance is 

 dominant over susceptibility, and there 

 is equal transmission by sire and dam, 

 and to sons and daughters. 



When the various races of mankind 

 are considered, a similar state of af- 

 fairs is found. Negroes are notorious- 

 ly susceptible to consumption ; so are 

 the American Indians, and in general, 

 all the aljoriginal peoples of the western 

 hemisphere, who have been exposed to 

 the disease only since 1492, and there- 

 fore have had not an opportunity to 

 develop, through natural selection, a 

 degree of immunity or resistance which 

 is found among some of the peoples of 

 the Old Word, where the bacillus has 

 been at work for thousands of years, 

 in all probability. And among the 

 races of the Old World, the dififerences 

 are striking enough : Louis Dublin has 

 pointed out that in the state of New 

 York the death rate from tuberculosis 

 among the Irish is some four times 

 as high as that of the Russians or 

 Italians, males being considered in each 

 case. 



The problem was long ago attacked 

 statistically by Karl Pearson and asso- 

 ciates, who showed in a number of 

 fundamental papers that there is about 

 as much resemblance between parent 

 and offspring, in prevalence of tuber- 

 culosis, as there is in respect of any of 

 the commonly accepted inherited traits 

 such as eye color or stature. On the 

 other hand, the resemblance between 

 husband and wife, in regard to tuber- 

 culosis, was not great, despite their pro- 

 longed and intimate association. All 

 the evidence indicated that heredity, 

 rather than mere contact with an in- 

 fected person, is the most important 

 factor in determining the incidence of 



^ Carnegie Institute of Washington, Eugenics Record Office, Bulletin No. 23. The 

 Hereditary Factor in the Etiology of Tuberculosis, by Albert Govaerts, M. D. Reprinted 

 from the American Review of Tuberculosis, Septem'ber, 1922, vol. vi, pp. 547-565. 



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