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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    The Ubiquitous Heterozygote 31 sary in the homozygous state for the disease to appear at all, we can see from Table IV that at least 1 out of every 16 people is heterozygous for this recessive gene. The hosts of people who reject the idea that heredity has anything to do with mental and physical diseases do so because they do not understand the concept of the ubiquitous hetero¬ zygote. Over and over again, parents protest that the spina bifida in their child could not have had an hereditary basis because they know that nothing like it had come out in their families for the last three generations at least. A rare gene could have been passed down through their ancestors since the birth of Christ without having become homozygous. This point should be obvi¬ ous, but it is a hard one to put across. The most practical use for human genetics is in counsel¬ ing. Unfortunately, at present most counseling occurs after the fact. The couple has already produced a defective child and want to know the probability of having another. The child with the anomalies has proved the parents to be heterozygotes, car¬ riers of the unwanted gene. It was an expensive way of provid¬ ing this information. Ideally, genetic counseling should be pre¬ marital so that if a prospective couple should be carriers of the gene for a serious anomaly they could be steered toward other Table IV The Ratio of Carrier to Affected Individuals for Cases of Simple Single Factor Recessive Inheritance (after Stern, 1960)