DNA: Up Close and Personal

We now look at personal genetics and genomics, especially important with the rise of companies willing to analyze your own DNA (for a small fee, of course), giving you the raw genetic information about yourself and your ancestors. Although we previously learned that DNA is “the same” in all species, we now turn to the individual, you, and explore how your DNA base sequence differs from the DNA base sequence of a bacterium, a liverwort, a chimp, and your weird Uncle Jason. This chapter provides the background to appreciate the specific issues related to medical and health issues, and then genealogical studies, coming up in later chapters. For most people, personal genomics testing involves sending a sample of DNA, in the form of spit or a cheek swab, to a lab. What kind of analyses do the labs perform, and what information do they reveal? In addition to full DNA sequence tests, there’s a whole gamut of other DNA tests, including SNP tests, Y-chromosome tests, mtDNA tests, and more. Your DNA base sequence is a gold mine of information unique to you, and it is entirely yours to discover. Whether you are curious about your medical and health genetics, wish to connect with relatives and build a family tree, or are just fascinated at what information your ancestors provided you, these next chapters will help you dig up the hidden secrets of your own genetic heritage.

Introduction

This introduction provides an overview of some common questions and misconceptions about DNA, while discussing its physical structure, how it works, and its impact on daily life. Also covered are chromosomes, genes, genomics, and what makes DNA so unique. DNA has generated quite a bit of interest due to major news stories of the last few decades. DNA is nature’s rock star. And, like many human celebrities, DNA can be mysterious, charming, enigmatic, complex, powerful, skilled, and at times unpredictable, but always awesome. This book pulls back the curtain to expose the machinery operating the molecule of life, showing that DNA, far from being ethereal and mystical, is actually logical, rational, usually parsimonious, and occasionally unpredictable. But still marvelously awesome!

Genetic Engineering, GMOs, and Genome Editing

DNA is the very core of human existence. The thought of humans manipulating the DNA base sequence of a living thing can be unsettling, disturbing, and sometimes intensely controversial. What are some of the techniques and what are some of the purposes? And what are the concerns? Chapter 10 considers the most controversial use of DNA technology: genetic engineering. It also explores twenty-first century technologies recently developed beyond the “old-fashioned” genetic engineering methods of the 1970s and ’80s. These newer technologies, with curious names, will soon be responsible for putting new products on the market. Synthetic DNA and gene drive are recent additions raising both exciting new possibilities and, simultaneously, old fears. New genome editing technologies, with cool names such as CRISP-Cas9, RNAi, Zinc Finger, and Talens, alter the native DNA in the genome—hence genome editing—and thus forego the need to add DNA from other species or to synthesize entirely. This strategy, say proponents, should quiet the concerns raised from those worried about introducing “foreign” genes from different species. Are you ready?

Your DNA Reveals Medical and Health Surprises

Why are so many people getting their DNA tested? Apart from the science nerds who are always up for such activities, there are two main reasons: health and genealogy. And for each of these there are subgroups. Traditional genealogists hit the proverbial “brick wall” and seek some means to break through, while some adoptees, desperate to find biological family, seem willing to try almost anything. On the other hand, those seeking medical information may have a family history of some frightening health condition, or—due to missing family histories—are in the dark about potential medical issues and want to find out. This chapter first explores personal genomics: the medical and health information held in your DNA base sequence, how to interpret that information, and what may be next on the horizon. What does all this data mean? Can it answer questions such as “Am I carrying around a ticking cancer bomb in my DNA, waiting for me to smoke one more cigarette, or eat one more hot dog before it activates a malignant tumor?”

Is Human DNA Special?

Chapter 3 explores “Human DNA” and the genetic features of human beings. Genetic inheritance in humans follows the same patterns and principles as those of other animals and plants, but far more scientists have studied humans than have studied any other species. Thus, scientists have accumulated a hugely disproportionate amount of information directly relevant to humans. This chapter examines some curious features of human evolution. Is there a genetic basis for human race and genetic “purity”? Are telomeres ticking time bombs inside cells limiting the human life span? How did most humans end up with Neanderthal DNA in their genomes? It’s just the way the DNA cookie crumbles. This chapter also introduces the use of technology based on DNA, from human DNA fingerprinting to probing human history.

Genetic Genealogy

We discussed genealogy DNA tests in Chapter 8. Here we focus on some practical matters to aid your engagement with genetic genealogy. We’ll survey which company you might choose for conducting your DNA test(s), explain how to interpret your results, and answer some common questions posed by genetic genealogy beginners (and even by some more advanced practitioners, too). Before seeking a company, identify what you hope to achieve. Different companies offer different types of tests, which reveal different genetic features and answer different questions, so knowing what you want to get from a DNA test will then allow you to choose from a list of companies offering that feature. Once you have a short list of suitable companies, you can choose based on practical criteria—price, convenience, appeal of website and presentation of data, privacy policy, and other factors. When you receive the results, you may want some help in interpreting the data and in identifying “matches,” your close and distant DNA relatives. We’ll also discuss a recommended free site, Gedmatch, and offer help for adoptees and others lacking known biological connections. In the latter half of the chapter we’ll explain some of the arcane terminology and address some common misconceptions encountered in the genetic genealogy community.

DNA Tests for Genetic Genealogy

This chapter covers the different types of direct to consumer DNA tests for genealogy. They are technically similar but a bit different from those used for medical and health conditions, as genealogy tests focus on identifying “matches,” or relatives who’ve also tested based on shared SNPs or other similarities. Consumers can choose from autosomal DNA, Y-chromosome, and mtDNA tests, depending on their interests and research goals. Unlike the other tests, genealogy DNA tests compare your results with those of others and predict a relationship based on the amount of DNA you share. This adds an extra layer of complexity but is no less rewarding, and the findings can be no less surprising. Understanding how these tests work and what they show enables consumers to choose the specific ones that will be most helpful in compiling their genetic genealogy.

Introducing Genetic Genealogy

DNA is a great tool for genetic genealogy and family tree construction. If you were blown away by your surprising medical DNA results, tighten your belt and hold on to your genes! A primary reason people test their DNA is to discover genealogical connections. What does DNA say about racial or ethnic differences among peoples of the world? Are you really related to your weird Uncle Charlie? How can it help an adoptee find his or her biological parents? The next chapters explain how to use DNA to connect to other humans, to break through that “brick wall” of traditional genealogy, or simply to confirm or refute a genetic relationship. DNA genealogy tests also provide information on your ethnic makeup. For instance, it may confirm or refute that old family rumor about Great Grandpa marrying a Native American princess!

Some Uncomfortable Ethical Dilemmas

This book has discussed the scientific aspects of DNA, physically, chemically, and biologically, and then the applications of knowledge of how DNA works. This chapter covers nonscientific considerations of the use (and abuse) of our knowledge of DNA and genetics. Scientific information can provide the foundation of public policy involving scientific issues, but scientific information alone does not lead to sound policies. Ethics and socioeconomic and political realities also form an integral part of healthy discussion and debates surrounding the limits to human applications of technologies. This chapter discusses some ethical issues raised by various applications of our knowledge of DNA.

Practical Applications Using DNA

Armed with knowledge of DNA structure and function, this book can now shift to applying knowledge of DNA and genetics to practical issues. Many of these are covered in social and mass media, often unsatisfactorily citing DNA as a key player but failing to reveal how DNA achieved the objectives. This chapter shows the mechanisms by which DNA and genetics answered the questions. It starts with what is likely the most dramatic, the forensic use of DNA in identifying criminals, followed by other situations in which DNA is used to identify people and wrapping up with examples of DNA clearing up some historical mysteries. Along the way some limitations to DNA technology in identifying specific people is considered, as well as some potential impacts on personal privacy.