Counseling in medical genetics / Sheldon C. Reed.

  • Sheldon Clark Reed
Date:
1963
Catalogue details

Licence: Attribution-NonCommercial-NoDerivatives 4.0 International (CC BY-NC-ND 4.0)

Credit: Counseling in medical genetics / Sheldon C. Reed. Source: Wellcome Collection.

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    Cures for Genetic Diseases 93 granted that a single pair of recessive genes is the major etio- logic factor. It follows that 20 to 25 per cent of the population are carriers of the gene (Dd). Such a high frequency of carriers for a clearly deleterious gene is evidence of genetic polymor¬ phism. This means that under some conditions the diabetic or the carrier has a reproductive advantage over the normal non- carrier that balances the deaths of those diabetics who have not completed their families. Post and White have attempted to find evidence for genetic polymorphism with some success. Post and White found that if both parents are diabetic, an average of 5.3 children are produced; if one parent is diabetic, the average is 5.0 children; if neither parent is diabetic, there are 4.6 children. These figures cannot be accepted at their face value, as no childless matings were included and these should affect these averages very significantly. However, the values are in the right direction, and the differences do not need to be this great to contribute to a polymorphic equilibrium. It is also known that diabetic children have an early adolescent growth spurt and presumably earlier sexual maturity. Post and White found that the menarchial age of 219 girls who developed diabetes at age 18 or over was 12.84 years. This menarchial age was younger than that of five groups of college girls that were available as controls. Larger and more elaborate studies are needed, as diabetes is an important disease that will increase in frequency for many years. In summary, the problem of counseling for diabetes is com¬ plicated by two factors: (1) insulin is successful in saving the life of the diabetic in most of the severe cases and gives prac¬ tically a normal life expectancy; (2) the gene for the disease is so common that the diabetic has a good chance of marrying a carrier. If a normal person is worried because there is diabetes in some relative, his anxieties can be dispelled by pointing out that every large kinship can be expected to have a diabetic member. The general recommendation for the diabetic person would be for