EDUCATIONAL RESOURCES Book Reviews

EDUCATIONAL RESOURCES Book Reviews HUMAN

-MGENETICS KEDUCATION

Am. J. Hum. Genet. 49:1129-1130, 1991

Principles of Medical Genetics. By Thomas D. Gelehrter and Francis S. Collins. Baltimore: Williams & Wilkins, 1990. Pp. 324. $34.95.

Gelehrter and Collins have produced an outstanding new book, the first fundamentally molecular textbook of medical genetics. The book is organized into 12 chapters. After a brief overview, the authors consider basic aspects of the structure and behavior of genes and chromosomes. They move on to Mendelian inheritance and then address population genetics and multfactorial inheritance in combination. The three chapters on basic molecular genetics and the molecular genetics of human disorders, as represented by the hemoglobinopathies and selected inborn errors of metabolism, are a highpoint. The chapters that follow address cytogenetics, gene mapping and linkage, cancer genetics, and clinical genetics. The book concludes with a chapter on the future as reflected in the Human Genome Project, genetic approaches to common diseases, and somatic gene therapy. Each chapter begins with an interesting and stimulating quotation. Most chapters include tables (range 0-11 /chapter, average 4/chapter) and figures (range 0-29, average 19) consisting of diagrams and photographs. Most chapters are followed both by specific references (range 0-17, average 4) relating to subjects addressed in that chapter and by more general suggested readings (range 0-18, average 7). Also provided are appropriate and interesting study questions (range 0-10, average 5), most of which require specific answers, while the remaining questions are meant to stimulate thought and discussion. Model answers to the study questions are available from the publisher. The final chapter is followed by a glossary containing 250 definitions. The book is well organized and easy to read. Headings are used to advantage. The index is complete and easy to

use. The two-tone print is both helpful and pleasant. The 3-inch outer page margins, sometimes used for figures or tables but often available for notes, give the book a more open feeling. Many of the diagrams are new and are outstanding in their clarity and information content. Although the book is focused on basic genetics, there are plenty of clinical examples to interest students. The authors have shown excellent judgment in making the difficult choices needed to achieve balance of subject matter in a book of manageable length. These choices have, however, left the coverage quite thin in certain areas; of the latter, probably the most important are Bayes's theorem and population genetics. The presentation of Bayes's theorem in the genetic counseling section of chapter 11, although clear, is so brief that few students will grasp its usefulness without further exposure. Correspondingly, none of the problems at the end of chapter 11 require Bayes's theorem for their solution. Combining population genetics with multifactorial inheritance is an interesting approach, but the former subject will need supplementation for most courses. The chapter on cytogenetics could be strengthened, for example, by including a discussion of the molecular basis for banding and of the relationship of genes to bands. This first edition does have a smattering of errors involving both the substance and the production of the book. Printing errors in three pedigrees and in one diagram were corrected after the first printing. On page 165 the authors state that "when nondisjunction occurs in the second meiotic division, the gametes will contain two identical copies of the same chromosome or neither." The copies of the chromosome are not identical, of course, since portions of one of the chromatids will have exchanged with its homologue during the first meiotic division. In another instance, the sizes of the segments exchanged in the reciprocal translocation 1129

1130 shown in figure 8.12 on page 169 are inconsistent, so the chromosomal segments in the quadrivalent in this figure do not match completely. Occasional presentations are unclear. The description of the Sanger sequencing method, on page 87, is too cryptic, both the text and the figure with its legend leaving unclear why and how a dideoxynucleotide forms the basis of this chain-termination method. Figure 8.20 on page 177 confused me greatly, particularly in regard to the "gray bag." On page 186 the paragraph regarding the fragile-X syndrome is poorly worded with regard to what "it" pertains to and what aspect of the fragile-X syndrome occurs in 0.4/2,000 females. The authors generally have been cautious in their statements regarding rapidly evolving subjects. Occasionally this has led them to omit useful information. For example, on page 212 we know more about the characteristics of mutations causing Duchenne, as opposed to Becker, muscular dystrophy than is indicated here. They were less cautious in regard to testis determination, however, and subsequently zfy has been replaced by sry as the genetic determinant of testis development (p. 178). I have not yet used this book for our own course, although we have decided to do so this year. Seeking student reactions, I consulted Dr. Peter Rowley, who used the book last spring in the University of Rochester's nearly 40-h course. He reported that the students considered the book to be excellent and very "user friendly." He indicated that several students found the book too advanced, however, and needed to go to the Thompson and Thompson textbook for a simpler treatment. On the other hand, some students wanted more detail and went elsewhere for more expanded presentations. This distribution of student reactions confirms for me that the authors have pitched the book at approximately the right level and leads me to expect very good acceptance of the book by students. Although it is certainly not the only excellent textbook of medical genetics, its appearance is certainly welcome. To state the matter briefly the fourth edition of Thompson and Thompson's Genetics in Medicine is more clinically oriented, covers a number of the traditional subjects in greater detail, and will probably be more readily comprehended by students with little background. The fourth edition of Sutton's An Introduction to Human Genetics is more biological in its approach and contains more detail in many areas. For some students, these and several other excellent texts will be useful as alternatives and supplements to Gelehrter and Collins's book. The availability of this book reduces enormously the growing amounts of supplemental molecular genetic material that most of us, to supplement the texts heretofore available, have spent much time organizing and reproducing for our own courses. Gelehrter and Collins's book either includes or touches on almost everything that medical geneticists generally want first-year medical students to know and

Human Genetics Education Section accomplishes this in a lucid, attractive, manageable-size volume at a reasonable price. RICHARD W. ERBE

Genetics Division Children's Hospital Buffalo ) 1991 by The American Society of Human Genetics. All rights reserved. 0002-9297/91 /4905-0033$02.00

Am. J. Hum. Genet. 49:1130-1132, 1991

Human Genetics. 2d ed. By John B. Jenkins. New York: Harper and Row, 1990. Pp. 544. $31.96. Human Heredity: Principles and Issues. 2d ed. By Michael R. Cummings. St. Paul: West 1991. Pp. 500. $43.40. Human Genetics (HG) and Human Heredity (HH) are textbooks for use in a one-semester course with no college science prerequisites. Both are remarkably congruent in organization. Each chapter begins with an outline of topics to be considered and is followed with an interesting passage to capture the reader's attention and to serve as an indication of that chapter's relevance. After the body of a chapter (amply illustrated with effective graphics) are a list of key words, summaries of fundamental concepts, bibliographic references, and problems. Answers to all questions and problems appear in a back section. Both books contain glossaries (numbers of items defined: HG 325; HH 359). When first introduced, key words appear in boldface type. HH has the additional feature of presenting short definitions of such terms in the wide margins of its pages. HH also includes a three-and-a-half page chronology of developments in genetics, an appendix reviewing principles of probability, and a final chapter entitled "Genetics, Law, and Bioethics." Although HH has fewer pages than HG, it contains more factual information, as permitted by its larger page size and smaller print. The physical appearance of the texts differs. The format of HH resembles that of most modern textbooks on life science. To provide versatility in graphics and accents, three colors-black and two shades of brown-are used in HH. HH also includes two sections of colored plates (25 colored figures)-"Genetic Disorders in Society, History and Art" and "Genetics." I believe these inserts would have greater pedagogical effectiveness if textual discussion explained their relevance. Also, to temper the section's Eurocentrism, this "gallery" would be enhanced by including material from non-Western cultures; e.g., Moche depictions of congenital anomalies in its ceramic huacos or Melanesian statues of hermaphrodites. In harmony with encouraged trends, such