Letters to the Editor

Abstract

LETTERS TO THE EDITOR Dear Sir: Nathaniel Weyl and readers of his article [1] may be interested to know that there are more and better estimates of the proportion (Ai) of genes in American Negroes which are of non-African origin than the ones he mentions. I recently critically reviewed the published estimates of ?? and provided several new estimates for Negroes from various areas of the United States [2]. Briefly, die results relevant to Weyl's article are: (1) The A0 gene (or chromosome) is not die best indicator of mixture; the Fy* allele of die Duffy blood group system is much better for several reasons, including the fact that, for a given sample size, the standard error of the estimate of M is much smaller. (2) Using Fy*, estimates of Af for New York City, Detroit, and Oakland, California, are not significantly different, and so the estimate based on the extensive data from Oakland , 0.220 ± 0.009, can be used as the best estimate so far for nonsoudiern Negroes. (3) The Fy* M-estimates for the two southern populations, Charleston (0.037 ± 0.009) and Georgia (0.106 ± 0.020), confirm the earlier belief of less mixture in the Soudi. (4) Earlier Ai-estimates, based on genes other dian Fy*, are suspect because die African frequencies in the former slaving areas are (excepting ABO) poorly known and/ or because their standard errors (which are never given) are usually large. references 1.Nathaniel Weyl. Perspect. Biol. Med., 13:618, 1970. 2.T. Edward Reed. Science, 165:762, 1969. T. Edward Reed Departments of Zoology and Anthropology University of Toronto Toronto 5, Ontario, Canada Dear Sir: When I submitted my paper on plantation slavery to Perspectives [1], I was not familiar with T. Edward Reed's article in Science for August 22, 1969, or cognizant of die strong case it makes for using Fy* in the Duffy group rather than R0 as an indicator of racial mixture (Ai). The values for M in the two studies used both by Reed and by me, however, are not far apart: he reports 3.66 percent for Perspectives in Biology and Medicine · Autumn 1971 | 147 Charleston and 10.6 percent for Evans and Bullock counties, Georgia; I report 3.6 and 9 percent, respectively. references 1. Nathaniel Weyl. Perspect. Biol. Med., 13:618, 1970. Nathaniel Weyl 4201 South Ocean Boulevard Delray Beach, Florida 33444 Dear Sir: In his recent article, H. Vasken Aposhian attempts to make a case in favor of rapid development of genetic engineering techniques to treat human genetic defects in Man [I]. In doing so, he overdramatizes the need for DNA as a therapeutic agent and ignores many of the scientific complexities which can now be visualized in die projected use of gene therapy in Man. For example, how is the new exogenous DNA to be stably integrated into the chromosomes of die recipient cells? Since production of too much of the new gene product (e.g., insulin or an enzyme) could be as harmful as too little, how will we insure diat die newly introduced genes are correctly regulated? Since the cells in die human body are differentiated and many gene products are produced only by small groups of specialized cells, how are we to insure that the new genes become integrated in the appropriate differentiated cells where they can be expressed? Is it not likely that we will be unable to devise a reasonably intelligent technique for gene therapy in Man until we know much more about the mechanisms of cell differentiation and regulation of enzyme synthesis in human cells? In our view, Aposhian blurs an important distinction when he repeatedly refers to DNA as a drug. On the contrary, projected DNA therapy in Man differs radically from conventional drug treatment in the sense that, if die added DNA does become an heritable part of the cell it alters, its effects will be irreversible. Conventional drug therapy can be discontinued if and when adverse side effects appear. DNA-mediated gene therapy, if technically successful, would be permanent for the lifetime of the cell which had been altered, but so would any adverse side effects. Aposhian attempts to allay...