How many genes do we have? Scientists estimated that there are probably 20,000 to 25,000 genes, which are essentially the molecular remote controls to our body's functionality. You should understand them properly in the grand scheme of your health, said Dr. Agus.
Many genes get translated into proteins, and these proteins make the stuff of our bodies. One protein makes hair; another makes cartilage; others make muscle. Besides those protein-coding genes, some genes are switches which turn other genes on and off. And, still other genes (i..e, body-plan genes) that give those switches orders. Together, in a complex cascade of timing and intensity, they combine to produce the amazing diversity of life on this planet. To learn more about the human genome, read .
In this article, we will look at two ways of tracking your genetic makeup, which may offer clues to your risk for certain ailments:
Genetically Inherited Diseases
DNA has a vital quality—it doesn't stay the same. When a baby is conceived, the fertilized egg receives half its DNA from the mother and half from the father, creating wholly new combinations. It's why we look a bit like our parents, but also different. Another way that DNA can change is mutation.
Mutations can happen as our DNA copies itself when our cells divide and our bodies develop. Sometimes, one of the DNA's chemical letters is replaced with another letter, sometimes letters are missing entirely. This can cause minute changes that no one is even aware of. But when mutations occur in the cells we pass down to our children, they can cause big changes, like rare genetic disorder named microcephaly.
Children with microcephaly are born with brains that can be a half the normal size. The reason is that a gene helps direct brain growth become defective. In his research, Dr. Chris Walsh has found that some 21 different mutations are responsible for microcephaly. These mutations stop the brain cells from dividing at a very early stage of development.
In 2010, one study by the Cleveland Clinic concluded that learning about your family tree is the best tool to predict genetic cancer risks. Family history is one of the most underused but extremely powerful tools to understanding your health. Patterns of familial illness can predict someone's brewing health risks.
Good family health trees are rare—a government survey estimated less than a third of families have one, and time-crunched doctors seldom push their patients to remedy that. To fill that gap, the US surgeon general operates a free website that will help you to create a family health history and share it electronically with relatives and your doctor.
In your effort to create a family health tree, you should follow up either parent's side of the family. For example, the threat of breast or ovarian cancer can lurk on either side of the family. Because genes seldom render our destiny, a family health tree should also reflect shared environmental or lifestyle factors that can further affect an inherited risk.
A single-nucleotide polymorphism (SNP, pronounced snip; plural snips) is a DNA sequence variation occurring when a single nucleotide — A, T, C or G — in the genome (or other shared sequence) differs between members of a biological species or paired chromosomes in a human.
SNPs occur every one hundred to three hundred bases along the 3-billion-base genome. They are thought to provide the genetic markers for our response to disease. These DNA differences do not cause the disease, but they are a marker of the relative risk of a disease. For example, the degree of genetic risk you inherit is related, in part, to how many risk markers you have residing at each SNP—none, one, or two.
Since the completion of the Human Genome Project, hundreds of studies have been published that describe the associations between SNPs and hundreds of specific diseases, traits, and conditions. These studies have opened the door for the personal genomics industry by providing a platform by which DNA, obtained through a simple saliva sample, can reveal your individual genetic map.
Before getting too excited about personal genomics, we need to understand that genetic testing is not a diagnostic test. For instance, it won't tell you if you have lupus or cancer. As Adam Siepel of Cold Spring Harbor Laboratory said:
The troubles with genome sequencing can be summarized as follows:
In summary, Genetic testing only shows your genetic predisposition to common conditions, so that prevention measures may be taken or early diagnosis may be made. Even though DNA sequencing may only give you a general list of your "ingredients" without telling you exactly how those ingredients mix and interact in your body, it does provide an important foundation to know more about your overall health. Knowing your genetic map, it also offers the potential for a personalized care using gene therapy[9,10] in the future.
Tracking or Not?
Should we find out our own genetic makeup or not? This has always remained controversial. However, let's conclude this article by echoing what Douglas L. Brutlag has said in :