Beverly Sankey, M.D., family care specialist with DeWitt Family Practice, has been interested in genetics and disease since she first worked at MSU Genetics. “We used to work with chromosome genetics,” says Dr. Sankey, “and examine the physical structure of chromosomes under high-powered microscopes to diagnose conditions like Downs Syndrome. We wanted to involve families of affected children, and give parents an idea of why the condition arose, and the chances for another child to be affected with the same disease.

“Now, we’re looking at molecular genetics as well as chromosomes. In cases where there is a known familial history, we can genetically screen for cystic fibrosis, sickle cell anemia, Huntington’s chorea, breast cancer (BRCA1 and 2 genes), Factor 5 Leiden for blood clotting issues and Factor H that leads to macular degeneration.”

A little background: In 2003, The Human Genome Project identified all the approximately 20-25,000 genes in the human DNA, and determined the sequences of the three billion chemical base pairs that comprise human DNA. From this project, it was found that all disease has some genetic component, whether inherited, or from the body’s response to environmental stresses, such as toxins or viruses. A key goal of the Human Genome Project was to find new ways to treat, cure, or prevent disease.

Most cells have 46 chromosomes, 23 from each parent. This set of 23 has 22 numbered chromosomes, plus one X or Y sex-determining chromosome. Females receive one X chromosome from both parents; males, an X chromosome from their mother and a Y chromosome from their father.

Genes are carried on chromosomes, and are the basic functional and physical units of heredity. Genes are specific sequences of bases that encode information on how to make proteins, which perform most life functions and make up our cellular structures. When genes are altered and proteins cannot form, genetic disorders can result. Likewise, DNA sequence mutations are either genetic or acquired. Many acquired mutations are repaired by special enzymes. When these special enzymes don’t operate efficiently, multiple mutations can result in disease.

A Whole New Ball Game

“Now that we’ve identified the whole human genome,” adds Dr. Sankey, “we are gradually seeing guidelines to test for certain diseases. For example, if I have a patient who has a history of familial breast cancer, I can be more proactive. I can order extra mammograms or MRI’s. I could order a genetics screen to see if the patient has the BRCA1 or BRCA2 gene mutation. Now, the patient has choices if they have the genetic mutations which link to breast and ovarian cancer. This also has implications for testing other family members.

“I think it’s important to be cautious as we approach genetic testing. There is a significant amount of patient-provider-insurer discussion that needs to occur. Ethical guidelines need to be established. We have a whole new set of insurance issues to deal with, if we move from current practices to genetic screens. I certainly don’t advocate home genetic test kits. You need to have a clinical interpretation of any genetic screen.

“We know certain diseases tend to run in families. Twins raised apart in different households still exhibit a higher incidence of the certain diseases. We are already testing for cystic fibrosis, Huntington’s chorea and Factor V Leiden. People with Factor V deficiency have blood that has a tendency to clot – not a good thing if you have a history of heart disease and stroke in your family.

“While it’s true that many genetically inherited or acquired diseases don’t appear until one is older, that’s not necessarily true with diseases like Parkinson’s. The actor Michael J. Fox was diagnosed in his early 30s.

“Multiple sclerosis is thought to be an autoimmune disease, where your body mistakenly directs antibodies and white blood cells against proteins in the myelin sheath that insulates nerve fibers in your brain and spinal cord. One of the most popular Mouseketeers, Annette Funicello, was diagnosed with MS in her early 40s.

“The brilliant physicist Stephen Hawking has been living for 35+ years with Lou Gehrig’s disease. His muscles, particularly around the sides of the spinal cord, have weakened and become paralyzed. He can move only a few fingers and needs a voice synthesizer and special computer to speak and write.

“I do foresee a future when, instead of just ordering lab tests, a genetic profile is obtained, along with a family history. The family physician pinpoints areas of genetic predisposition, and we start education and early intervention to prevent these diseases from taking a foothold.

“Likewise, there are so many medications for various conditions and diseases. But each person metabolizes medication differently. If we were able to genetically test the body’s pathways to see how the body breaks down certain chemicals and metabolizes them in the liver, we may select a medication that better fits your body’s metabolic pathways. “Molecular genetics is one avenue toward changing the way we approach early-on medical intervention and treatment. It doesn’t change patient responsibility for eating healthy foods, getting appropriate exercise and sleep. But it does change the patient-physician dynamic in talking about your body’s unique genetic composition.”