Genetic Counseling PDF
Preview Genetic Counseling
Walter Fuhrmann Friedrich Vogel Genetic Counseling Third Edition Translated by Sabine Kurth-Scherer With 50 Figures Springer-Verlag New York Heidelberg Berlin Walter Fuhnnann Institut flir Humangenetik Giessen, West Gennany Friedrich Vogel Institut ffir Anthropologie und Humangenetik Heidelberg, West Gennany Sponsoring Editor: Chet Van Wert Production: Kate Ormston Library of Congress Cataloging in Publication Data Fuhnnann, Walter, 1924- Genetic counseling. Translation of: Genetische Familienberatung. Bibliography: p. Includes index. 1. Genetic counseling. I. Vogel, Friedrich, 1925- ll. Title. RBI55.F813 1983 616'.042 82-10630 © 1969, 1976, 1983 by Springer-Verlag New York Inc. Softcover reprint of the hardcover 3rd edition 1983 All rights reserved. No part of this book may be translated or reproduced in any fonn without written pennission from Springer-Verlag, 175 Fifth Avenue, New York, New York 10010, U.S.A. The use of general descriptive names, trade names, trademarks, etc., in this publication, even if the fonner are not especially identified, is not to be taken as a sign that such names, as understood by the Trade Marks and merchandise Marks Act, may accordingly be used freely by anyone. While the advice and infonnation in this book is believed to be true and accurate at the date of going to press, neither the authors nor the editors nor the publisher can accept any legal responsibility for any errors or omissions that may be made. The publisher makes no warranty, express or implied, with respect to the material contained herein. Typeset by Ms Associates, Champaign, IL. 9 8 7 6 5 4 3 2 1 ISBN-13: 978-0-387-90715-4 e-ISBN-13: 978-1-4612-5435-5 DOl: 10.1007/978-1-4612-5435-5 Preface to the Third Edition This third edition of Genetic Counseling has been thoroughly revised to reflect current practice. In particular, the chapter on prenatal diagnosis (Chapter 10) has been largely rewritten and considerably expanded, reflecting the rapid develop ment in this field and its increasing medical importance. This chapter provides a detailed description of the alpha-fetoprotein test and a brief description of ultrasonography for the diagnosis of morphologic defects. Further, we discuss fetoscopy and the sampling of fetal blood with the aid of a fetoscope. In this as in past editions, these descriptions are not meant as working instructions for actual practice, but rather as background for the general practitioner who is dealing with the problems of genetic counseling. We have added a chapter (Chapter 7) on the use of conditional probability (Bayes Principle) for the calculation of more exact specific risk figures. It is true that the daily practice of medicine sees far fewer situations in which these methods can reasonably be applied than some theoreticians like to think. However, the usefulness of these methods has recently increased, especially in cases of X-chromosomal recessive diseases where the termination of a preg nancy, if the fetus has been ascertained to be male and if the mother is "most probably" heterozygous, has become more commonplace. With such a trend, the degree of probability must be determined as exactly as possible. The last chapter (Chapter 16), concerning the psychological and social aspects of genetic counseling, has also been expanded considerably. Special attention is devoted to the best practical procedures in the coun~eling process and in situations where prenatal diagnosis is indicated. We have gone into consider- vi Preface to the Third Edition able detail because, as genetic counseling becomes a more common or routine phenomenon, the chance that painstaking care and tact will be neglected in dealing with families seeking help increases. The care we take in counseling is essential to maintaining the public's present general approval and acceptance of genetic counseling. When genetic counseling was in its infancy, those who came for counseling were often from the upper-middle classes. They tended to be fairly well educated, at least high-school graduates, often with university degrees as well. This meant that they spoke more or less the same "language" as their counselors. Today, a much larger part of counseling is devoted to working-class farnilies-a very important development since it is precisely these families that are most severely burdened when a family member is mentally or physically handicapped. However, their educational background does create special com munication problems, which require careful consideration. We sincerely thank all of our colleagues whose suggestions and critical comments have helped us with this and past editions. Preface to the First Edition An ounce of prevention is worth a pound of cure. In medicine the truth of this statement is so self-evident that we simply take it for granted; and yet it has become mere lip-service for many a doctor, since his work is almost exclusively concerned with the treatment of those who are already ill. This applies not only to the treatment of patients but even more to that of entire families. Many doctors are as yet unaware that the appearance of serious, sometimes fatal diseases can be avoided by preventing the conception of congenitally disadvantaged human beings. Our knowledge of genetics permits the relatively accurate prediction, based on statistical probability, of the recurrence of genetic defects (anomalies) and diseases within families. Our patients are frequently aware that such predictions are possible. In an effort to prevent the birth of abnormal children they try to educate themselves. However, in the practice of the individual doctor this sort of inquiry does not occur with such frequency that he is forced to concern himself systematically with these problems. Should he be confronted with such an inquiry, the doctor conscientiously tries to recall what he has read---once upon a time. In many cases the doctor's actual contact with genetics has occurred so long ago that he has forgotten most of the particulars. Consequently, the practising physician usually has no exact knowledge on which to base his advice. Either he evades the problem with vague generalities, or he remembers various statements about "heredity" that almost always lead to false conclusions. From discussions with our colleagues, we know that they recognize the problems and worry about them, but simply do not have the time to study thoroughly the highly specialized genetic literature available. viii Preface to the First Edition This book is an attempt to fill this gap. We have made an effort to keep it as short and clear as possible and to limit it to the important and most frequent genetic abnormalities. In particular, we have tried to take into consideration the difficulties of the average student in understanding genetic logic in order to avoid errors. This guide is not designed to provide more than basic information. No reader will arise from the study of this volume an expert genetic counselor. That requires, as in all other sciences, knowledge of the highly specialized literature as well as extensive experience. Some geneticists therefore take the position that the general practitioner (or specialist in any other field of medicine) cannot possibly give proper genetic counsel to his patients: because he is not a genetics expert, he should, without exception, refer all such cases to the geneticist. This point of view would condemn this guide as potentially more harmful than helpful, since it might increase the incidence of well-meaning error as well as encourage those who are not competent in this field to deal with problems that are beyond their capacity. We, obviously, do not share this pessimistic standpoint. In our opinion, there are cases in which an interested and informed general practitioner can give fully adequate counsel. In these cases it is of great advantage to the effectiveness of the advice that the family doctor who has the confidence of his patient(s) also carry out the counseling. Opposed to these clear cases are the highly complex ones which exceed this guide's range. In such cases the doctor must recognize the limits of his knowledge and consult a genetic counseling clinic or a specialist. Exactly where the limits are to be found in any specific case must be left to the conscience ofthe individual doctor. We are confident that the doctor, once he has become aware that genetic problems are often very complex indeed, will consult the specialist too often rather than too seldom. Even if the doctor has come to the conclusion that he cannot responsibly counsel in any such case, the information in this guide will help him to understand the nature of the problem with which the specialist is confronted. It will, moreover, help him to recognize problems that require specialist attention and allow him to aid the specialist in gathering relevant information. We sincerely hope that this guide will prove helpful to many practising physicians and beneficial to patients and their families. Contents Chapter 1 Appearances Deceive Chapter 2 Recording a Family Medical History or Pedigree 14 Chapter 3 The Autosomal Dominant Mode of Inheritance ........... 18 Chapter 4 New Mutations and Nonhereditary Cases (phenocopies and Somatic Mutations) .................. 25 Chapter 5 The Autosomal Recessive Mode of Inheritance and Tests for the Detection of Heterozygotes 36 Chapter 6 Sex-linked Modes of Inheritance 47 Chapter 7 How Can Additional Information Be Incorporated into Genetic Risk Calculations? ............................. 52 x Contents Chapter 8 Chromosomal Aberrations 71 Chapter 9 Malformations Not Subject to a Simple Mode of Inheritance ........................................ 93 Chapter 10 Prenatal Diagnosis of Genetic Abnormalities and Diseases ......................................... 106 Chapter 11 Other Diseases Without a Si mple Mode of Inheritance ... 122 Chapter 12 Mental Retardation and Mental Illness .................. 129 Chapter 13 Genetic Prognosis for a Consanguineous Marriage ....... 140 Chapter 14 Exposure to Mutagenic Noxes .......................... 148 Chapter 15 Teratogenic Effects During Early Pregnancy .............. 153 Chapter 16 Psychological and Social Considerations 159 References ........................................... 169 Index ................................................ 177 Genetic Counseling Third Edition
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