1. Race and Medicine: Introduction
Like all the topics we have encountered this semester, the question of the biological and medical significance of racial categories is an incredibly complex topic that we could easily spend a whole semester exploring. Unfortunately, in the limited time available to us we will have time only to introduce the issues surrounding this currently controversial topic. As I see it, we could delve into the following three major areas.
1.1. Is race a “useful” or “real” way to categorize human beings?
A great many critiques of the concept of race have been written from the standpoint of anthropology, biology, and social science. We start by reading Jonathan Marks’ essay "Scientific and Folk Ideas about Heredity," which summarizes some of the anthropological criticisms of the concept of race. He starts his essay by pointing out two assumptions that he considers to be incorrect.
Human races represent natural categories of people. This is still a hotly debated topic with recent evidence from DNA sequence analysis being used to both support and criticize this idea.
One has more in common with other people of the same race than one has with people of other races. This has generally been proven to be incorrect, although to the extent that one's race represents shared genetic ancestry, it may be the case that specific genetic traits or diseases occur at a higher rate in one group vs. another.
Scientific and Folk Ideas about Heredity Jonathan M. Marks from The Human Genome Project and Minority Communities (Zilinskas, R.A, & Balint, P.J., eds.) Praeger, Westport, CT (2001)
1.2. Is race a biologically real phenomenon?
The key argument against race as a biologically significant classification is the discovery that 85-90% of the genetic variation between individuals is found within each racial group and that only 10-15% of the genetic variation between humans is found between racial groups. What this meant was that for many years it was impossible to identify the race of a human based on biological markers. Yet clearly, at the crudest level, race is based on biological differences between human groups. Morphological features like skin color, facial features, and hair characteristics have long been used to assign individuals (often incorrectly) into one racial group or another. Yet this has long been recognized as a very crude and not very meaningful (biologically) set of measures. More recently, large data sets of single nucleotide polymorphisms (SNPs) have allowed the discovery of a set of SNPs that appear to accurately assign individuals to groups based on shared geographical ancestry. The meaning of that dataset is still hotly debated.
A genetic melting-pot M.W. Feldman, R.C. Lewontin and M-C King Nature (2003) 424 p 374
I am not assigning the following articles because of their technical complexity and the limited time we have to cover this topic, but the following set out the current debate in the biological reality of race. I encourage you to look at some of these.
Genetic variation, classification and ‘race’ Jorde, L.B. and Wooding, S.P. (2004) Nature Genetics Supplement 36: S28-S33
Implications of biogeography of human populations for ‘race’ and medicine. Tishkoff, S.A. and Kidd, K.K. (2004) Nature Genetics Supplement 36: S21-S27
Assessing genetic contributions to phenotypic differences among ‘racial’ and ‘ethnic’ groups. Mountain, J.L. and Risch, N. (2004) Nature Genetics Supplement 36: S48 – S53
Are medical and nonmedical uses of large-scale genomic markers conflating genetics and ‘race’? Rotimi, C.N. (20040 Nature Genetics Supplement 36: S43-47
1.3. Is race a useful characterization in deciding courses of medical treatment?
The above two topics then bring us to the extremely controversial topic of the use of race in medical care. We have known for some time that specific alleles of genes involved in drug metabolism are found at different frequencies in different populations (races). However, this brings us back to a topic that we have explored before in several different contexts – the fallacy of “fold” differences. Let us say that allele B of a gene occurs at a tenfold higher frequency among Asians than it does among Caucasians and that this allele makes individuals who carry it more sensitive to drug X. Does this mean we should prescribe lower doses of drug X to Asians to obtain the same effect? Not necessarily! Let us say allele B occurs at a frequency of 5% in the Caucasian population. We would then expect that fully 50% of the Asian population would carry this allele – a much higher proportion indeed. However, half of the Asian population still does NOT carry allele B and would thus need the full dose of drug X. In addition, given the large number of individuals with mixed racial heritages, it is dangerous to use a crude measure such as race (generally self-identified) in critical medical decisions. This is a very controversial topic with people of good faith on both sides of it. We will examine the specific case study of BiDil, the first “racial medicine” approved by the FDA.
Editorials by R.S. Schwartz (Racial Profiling in Medical Research) and A.J.J. Wood (Racial Differences in the Response to Drugs – Pointers to Genetic Differences) (2001) N. Eng. J. Med. 344: pp 1392 – 1395
The Importance of Race and Ethnic Background in Biomedical Research and Clinical Practice by Burchard, E. G. et al (2003) N. Eng. J. Med. 348: 1170-1175
Combination of Isosorbide Dinitrate and Hydralazine in Blacks with Heart Failure Taylor, A.L. et al (2004) N.Eng. J. Med. 351 (20) p 2049 – 2057.
Race-Based Therapeutics” Bloche, G-B . N. Engl J. Med. 351 (20) p 2035-2037 (2004)
BiDil: False Promises by J. Kahn (2005) GeneWatch 18 (6) p 6-9.
Misreading race and genomics after BiDil J. Kahn (2005) Nature Genetics 37: 655-656.