Genetics, revised edition. Karen Vipond
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a genetic text applicable for health care practice. Common feedback obtained from health care students in the past has identified the lack of an available suitable genetic text. Many students have resorted to texts designed and written for medical students or for biology undergraduates. Most of the students felt that sections of these texts were either too in-depth or irrelevant to health care practice and therefore wanted a text that was relevant to them. This book was written primarily for student nurses, but the information within the book is also relevant for all other health care students, as well as for qualified professionals who would like to brush up on their knowledge of genetics.
The book is set out in ten chapters, starting with the very basics of cell biology. It has been designed so that each chapter builds upon the information given in the previous chapters. However, this does not mean that you have to start at Chapter 1; the chapter you start with will depend upon your prior knowledge and understanding of biology and genetics. Some readers might want to use the book as a reference source for genetic disorders; others might want to use it as supporting material for their health care course.
BOOK STRUCTURE
All the chapters have been written as clearly and concisely as possible in order to actively support learning. The book is organised as follows.
Chapter 1: Basic Cell Biology
This chapter provides a basic overview of the functions of the cell in relation to protein synthesis. Chromosomal structure is examined together with the basic units of inheritance, the genes. This is addressed to individuals who have no previous knowledge of cell biology.
Chapter 2: Inheritance
The Mendelian principles of transmission are explained in this chapter by using common genetic traits as examples. Possible allele combinations in offspring are demonstrated through the use of Punnet squares. Exceptions to the Mendelian rules are also outlined in this chapter.
Chapter 3: Autosomal Recessive and Dominant Inheritance
The inheritance of genes that are situated on the 22 paired autosomes are explained in this chapter, including examples of conditions that affect health. Transmission of recessive and dominant genes is explained, together with the classification of gene action. Incomplete dominance and co-dominance are outlined as well as the action of lethal alleles.
Chapter 4: Sex-linked Inheritance
The structure and the inheritance patterns of the X and Y chromosomes are explained in this chapter. Examples of genetic disorders arising from genes carried on the sex chromosomes are provided. X-inactivation through Barr bodies is explained as well as the process of Lyonisation. Sex-limiting and sex-influenced alleles are also explained in this chapter.
Chapter 5: Two or More Genes
This chapter covers both monogenic and polygenic inheritance. The calculation of probability of two or more monogenic traits is explained as well as the additional effects of polygenic traits. Multifactorial inheritance of common disorders such as diabetes, mental health problems and cardiovascular disease is explained, together with the heritability and empiric risk measurements of inheriting a multifactorial condition.
Chapter 6: Mutations
Chromosomal abnormalities and gene alterations are explained in this chapter.The different classifications of mutations, together with examples of clinical genetic conditions, are provided.
Chapter 7: Pedigree Analysis
The ability to take a family’s medical history is essential to detect the mode of inheritance of a genetic condition and to estimate an individual’s risk of developing that condition. This chapter explains the way in which pedigree charts are constructed, together with the recognised symbols, and opportunities are provided to practise the drawing of pedigree charts.
Chapter 8: Clinical Applications
Genetic screening, testing and gene therapy are explained in this chapter. Advances in technology have led to significant changes in health care, especially with regard to pharmacogenetics or ‘personalised medicine.’ Although many advances are still at the clinical trial stages, these are also explained in this chapter.
Chapter 9: Cancer Genetics
There has been a rapid development in the knowledge and understanding of genetics relating to different forms of cancer over the past decade, especially in relation to risk assessments, pharmacogenetics and disease prevention. Knowledge of cancer genetics has now become essential for all areas of health care and not just for those working in oncology units. The basics of cancer genetics are explained in this chapter, together with examples of some common cancers.
Chapter 10: Genetic Counselling
This chapter covers the specialist genetic services on offer to patients. Issues such as the aims of the service, appropriate referrals and the ethical issues of genetic testing are outlined. Access to accurate and relevant information is also covered, given that there is so much information and misinformation available on the Internet.
ACTIVITIES AND COMPETENCIES
There are plenty of activities included within the book for you to test your understanding before moving on to the next topic. Most importantly, answers to the activities are supplied at the back of the book. Most health care professionals are constantly involved in the caring for people with genetic conditions, and this book will provide you with genetic knowledge so that you can achieve the workforce competencies while you are working with patients.
The information provided in different chapters relates to different workforce competencies, but Chapters 1 and 2 form the basic foundation knowledge of the science of genetics.
Table 1 UK Workforce Competencies for Genetics in Clinical Practice for Non-Genetics Health Care Staff (National Genetics Education and Development Centre, 2007)
| Workforce Competency | Relevant Chapter |
| 1. Identify where genetics is relevant in your area of practice | 3, 4, 5, 6, 7, 8, 9, 10 |
| 2. Identify individuals with or at risk of genetic conditions | 3, 4, 5, 6, 7, 8, 9, 10 |
| 3. Gather multi-generational family history information | 7 |
| 4. Use multi-generational family history information to draw a pedigree | 7 |
| 5. Recognise a mode of inheritance in a family | 3, 4, 5 |
| 6. Assess genetic risk | 2, 3, 4, 5 |
| 7. Refer individuals to specialist sources of assistance in meeting their health care needs | 10 |
| 8. Order a genetic laboratory test | 8, 10 |
| 9. Communicate genetic information to individuals, families and other health care staff | 10 |
AUTHOR BIOGRAPHY
Karen Vipond is a lecturer at the School of Healthcare Sciences at Bangor University, UK. She has combined her different careers as a biologist and a nurse in order to teach biological sciences to health care professionals. Karen’s career experiences have been quite varied as she has worked as a biologist, a teacher, a trauma nurse, a district nurse, a health visitor and a medical research co-ordinator for Oxford University and the World Health Organization. Karen was a student at St Anne’s College at the University of Oxford as well as Oxford Brookes University and she trained as a nurse at the John Radcliffe Hospital, Oxford. During her clinical career she worked in Oxfordshire, Buckinghamshire and in North Wales.
ACKNOWLEDGEMENTS
I would like to thank the following individuals for their help in the production of this book:The staff and students at the School of Healthcare Sciences at Bangor University for acting as ‘models’ for the photographs in Chapter 2; Ifor Williams, IT Technician at Bangor University for taking the photographs in Chapter 2; Marion Poulton, Librarian at the School of Healthcare Sciences for her help with proofreading the work; Carolyn Owen, Genetic Counsellor at Ysbyty Gwynedd, Bangor, for being a critical reader for Chapter 10; Joshua Vipond for his work in checking the scientific explanations of inheritance throughout the book; Judith Harvey for all her help and advice during the whole process of writing the book.
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