Walter Fuhrmann – författare

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.

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.

viii From discussions with our colleagues, we know that they recognize the problems and worry about them, but simply do not have the time to thoroughly study the highly specialized genetic literature available. This book is an attempt to fill this void. 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 abnor­ malities. In particular, we have tried to take into consid­ eration the difficulties of the average student in under­ standing genetic logic and to eliminate the most common errors. This guide is not designed to provide more than basic information. No reader will arise from the study of this volume as an expert genetic counselor. That requires, in this as in all other sciences, knowledge of the highly spe­ cialized 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 in that it might increase the cases of well-meaning error as well as encouraging those who are not competent in this field to deal with problems which are beyond their capacity. We, obviously, do not share this pessimistic standpoint.

"An ounce of prevention is worth a pound of cure" In medicine the truth of this statement is so self-evident that it is simply taken 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 concep­ tion of sick 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 pos­ sible. In an effort to prevent the birth of defective children they try to inform 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.