Book Review: The Human DNA Manual — Understanding your genetic code

DNA-themed products are becoming increasingly common within the consumer marketplace. Companies claim to be able to design cosmetic packages, fitness programmes and dietary regimes based on the genetic make-up of each individual client. However, genetic literacy within the general population is typically poor, which may make it difficult for potential customers to scrutinise these products with a discerning eye.

Dr Melita Irving, a consultant in clinical genetics at Guy's and St. Thomas' Hospital, has created 'The Human DNA Manual – Understanding Your Genetic Code', a comprehensive reference book, which has the potential to improve genetic literacy by examining the many ways in which the study of DNA impacts our modern-day lives.

The Human DNA Manual starts by introducing the reader to the fundamental science that underpins the field of genetics, including, the basic structure of DNA and how the genetic code translates into physical characteristics. The information is broken down into short, 2-4-page segments, which are easy to digest and are supported by a plethora of large, colourful illustrations.

Dr Irving explores the pioneering research that contributed to the discovery of DNA and describes how research efforts, such as the Human Genome Project and the 100,000 Genomes Project, are continuing to advance our understanding of the genetic code and the complex regulatory systems that control its expression.

The relationship between DNA and the process of evolution is also examined. Dr Irving describes how modern humans – Homo sapiens – represent an accumulation of genetic adaptations that have enabled us to thrive in our current environment. It was particularly illuminating to learn how ancient DNA, which has been recovered from fossilised predecessors of modern Homo sapiens, is being used to 'unravel the history of the human species'.

The subsequent chapters of the book explore how the study of DNA has become incorporated into contemporary culture and how it is used on a day-to-day basis. The chapter, 'How we use DNA today', explores how DNA profiling can be used by forensic teams to aid crime investigations and prevent 'miscarriages of justice'. Dr Irving successfully creates an engaging narrative by using real-life examples of how DNA evidence has been used in criminal trials and explains how household objects such as hairbrushes and toothbrushes can be used to obtain DNA samples.

This chapter also addresses how advances in DNA sequencing technologies have enabled the development of direct-to-consumer (DTC) genetic testing kits. The reader is provided with unbiased information about the potential pros and cons of undergoing genetic testing using a DTC kit, however, Dr Irving takes care to emphasise the complex nature of genetic testing and the wide spectrum of results that can be obtained, including surprises, such as non-paternity where the expected father is found not to be the biological parent.

Readers are encouraged to think about whether DTC consumer testing is right for them by taking part in a 'DTC genetic testing quiz'. The quiz prompts readers to carefully consider why they want to take the genetic test and how they would feel if they received significant test results without any access to professional support. Dr Irving also encourages potential DTC test participants to ask questions about how their genetic data would be used and stored by the testing company, such as, who would own the genetic data? Is the data encrypted? Can the data be sold on to a third party?

The book successfully brings a sense of fun to genetics. In addition to the DTC genetic testing quiz, the book also includes several interactive challenges, which have been designed to enhance the readers understanding of the subject matter. The section describing how ancient DNA is extracted from Neanderthal bone fossils is accompanied by a simple DNA extraction protocol that the readers can perform at home to extract DNA from strawberries, kiwis and bananas.

The readers can also take part in the 'cracker test' to estimate how many copies of the AMY1 gene they possess. The AMY1 gene encodes the protein amylase, which breaks down starch into glucose, and the speed at which salt-free crackers start to taste sweet to an individual has been found to correlate with their AMY1 gene copy number.

An entire chapter of the book is dedicated to the role of 'DNA in medicine'. Dr Irving explores the heritable nature of some medical conditions, such as cystic fibrosis, and the availability of genetic screening to identify the cause of a rare disease or to confirm a clinical diagnosis. The readers are also introduced to the field of genetic counselling, where healthcare professionals can help patients understand their risk of developing a specific disease based on their personal genetic information and the medical history of their family. The patient's risk of passing a genetic condition onto their offspring can also be calculated and preconception and/or prenatal options can be discussed.

The book ends by exploring how genetic information may be used in the future, particularly within a hospital setting. Dr Irving explains how medical professionals are striving towards the provision of individualised treatment based on the DNA profile of the patient, with the aim of providing more effective medical care with fewer side effects.

The potential for gene therapy and genome editing to be used to ameliorate genetic conditions is also examined. However, Dr Irving balances the excitement surrounding these potential technological advancements with an examination of the ethical and moral concerns that surround the use of such technology.

Overall, the book is both engaging and visually impactful and would be of interest to anyone wanting to deepen their understanding of DNA and genetics. The book has been designed to be accessible to all audiences and would be suitable for both lay individuals with a budding interest in biology and young adults and university students who are interested in working in this exciting scientific field.

Buy The Human DNA Manual: Understanding Your Genetic Code from Amazon UK.