Archive For: Medical Tests

20,000 and You: Unlocking the Genetic Code

In just the past few years, there has been a significant shift in the practical uses of genetic testing, which examines changes, or variants, in your genes that may lead to illness or disease. Once considered more of an investment in the future and less applicable to individual patient care, opportunities to guide health and lifestyle decisions in the here and now may be tantalizingly close at hand.

“Genetic testing is progressing from an occasionally deployed diagnostic tool to becoming the new founding architecture of a personal health record, and may ultimately become a vital addition to a patient’s clinical portfolio,” explains Calum MacRae, MD, geneticist, Chief of Cardiovascular Medicine at Brigham and Women’s Hospital and in private practice at Boston’s AllCare Medical, whose decades-long focus has been on how to systematically implement genomics discoveries into clinical care.

In broad strokes, three areas are identified through genetic testing: disease carrier states for genes, important to the patient’s immediate family; inherited diseases such as heart disease or cancer; and an emerging predictive utility for drug responses and risk of common diseases. This information forms the foundation of personalized medicine, targeted to a patient’s specific genetic profile. According to Dr. MacRae, a holistic approach will optimize the enormous potential of genetic testing, allowing physicians to engage all their patients to understand their own genomes and build collaborative plans for lifestyle modification, nutritional choices and medications that may prevent or delay disease.

Direct-to-consumer (DTC) testing such as 23andMe has become ever more mainstream and is predicted to grow to a $340 million industry in the next five years. In fact, earlier this year, the FDA began allowing 23andMe to provide DTC testing for increased risk of 10 conditions, including celiac disease, hereditary hemochromatosis, Parkinson’s, alpha-1 antitrypsin deficiency and late-onset Alzheimer’s disease.

However, experts cast a wary eye on DTC testing for a number of reasons. Genetic testing is highly technical and complex and it is still hard to predict who will actually develop common diseases such as diabetes, hypertension, and many cancers from genes alone. For many conditions, a negative DTC test result does not necessarily guarantee low risk because it is believed to be the interaction of complex environmental factors with genes that cause disease. That means all information must be considered in the context of a patient’s environment, lifestyle and family medical history, ideally explored during a one-to-one consultation with a primary care physician.

While there is still much to be uncovered, there is no denying the desire to incorporate personalized medicine in clinical practice is increasing. Scientists are beginning to understand the interplay of genes and environment on disease for about one third of the roughly 20,000 genes we all possess, and the portfolio of knowledge continues to grow rapidly. Even more comprehensive tests that examine numerous genes and variants in an individual’s exome (the protein-making part of the gene), known as next generationgeneration sequencing, will gradually become accessible as the costs associated with them continue to fall. Technologies that enable scientists to alter an organism’s DNA (see below) are being refined. With every advance, we may come closer to realizing the vision of Dr. J. Craig Venter, one of the primary forces behind the original Human Genome project, who said in 2015: “I’m hoping that these next 20 years will show what we did 20 years ago in sequencing the first human genome was the beginning of the health revolution that will have more positive impact in people’s lives than any other health event in history.”

Coming to Terms with Genetic Testing

  • Chromosomal microarray: looks for genetic changes in the genome, sometimes caused by an existing medical condition.
  • Genome editing: technologies that enable scientists to change an organism’s DNA by adding, removing or altering genetic materials at particular locations in the genome. Gaining favor is the newest CRISPR technology, less expensive and more accurate than other genome editing methods.
  •  Single nucleotide polymorphisms or SNPs: the most common type of genetic variation among
    people. They can act as biological markers, helping locate genes associated with disease, and may help predict an individual’s response to certain drugs, susceptibility to environmental factors such as toxins and risk of developing particular diseases.  SNPs can also be used to track inheritance of disease genes within families.
  • Genotyping panels of selected susceptibility variants: often used in DTC genetic tests, and include SNPs that have been associated with common, complex diseases such as type 2 diabetes, autoimmune disease and metabolic traits.
  • Specific single gene tests: performed as part of a focused risk evaluation for heritable disease or for diagnostic considerations e.g. BRCA1 and BRCA2 gene sequencing for carrier identification in at-risk individuals with a strong family history of breast cancer.

Source: Up to Date

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Unlocking the Genetic Code: Spotlighting Pharmacogenomics

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This is the first in a series exploring some of the most promising advances inspired by the Human Genome project. From the burgeoning field of pharmacogenomics to consumer genetic testing such as 23 and Me, the time from discovery to application is progressing rapidly. We’ll look at some of the latest thinking and its impact on personalizing medicine in the future.

To boil down a complex subject to its very human goal, pharmacogenomics means using genomics to get the right dose of the right drug to the right patient at the right time. There is tremendous variability in individual response to drugs, and a large percentage of adverse drug reactions may be due to genetic variables that are just beginning to be really understood.

It’s important to note that while significant progress has been made, the actual use of pharmacogenomics in primary care may be many years away and unlikely to impact the way in which your physician currently prescribes medications for you. However, as research continues to accumulate, the medical community is hopeful that this information will someday help guide prescription decision-making in a much more precise and personalized way.

Did You Know?

1957 – Dr. Arno Motulsky suggests that individual differences in drug efficacy and adverse drug reactions are at least partially attributable to genetic variations

2008 – The Food and Drug Administration releases a table listing genomic biomarkers with established roles in determining drug response

Sources: The National Human Genome Research Project, UptoDate, FDA.gov, JAMA

What we know now

Slightly different, but normal, variations in the human genetic code can yield proteins that work better or worse when they are metabolizing different types of drugs and other substances. Even small differences can have a major effect on a drug’s safety or effectiveness for an individual patient. Your drug-metabolizing enzymes may be set to act in a completely different way than a friend of similar height and weight because phenotypes range from ultrarapid and rapid metabolizers to normal, intermediate and poor metabolizers.
Consider this example from the National Institutes of Health: The liver enzyme known as CYP2D6 acts on 25 percent of all prescription drugs, including the pain reliever codeine. There are more than 160 versions of the CYP2D6 gene, and many of these vary by only a single difference in their DNA sequence. People who manufacture an overabundance of CYP2D6 enzyme molecules metabolize the drug very rapidly, and as a result, even a standard dose can be too much. Conversely, those who carry a CYP2D6 gene that results in a slowly metabolizing enzyme may not experience any pain relief. Armed with this kind of information, a physician may be able to prescribe different types of pain relievers for both of these patients.
The Food and Drug Administration now includes pharmacogenomic information on the labels of some medications, with details on risk for adverse events and side effects, effectiveness for people with specific genome variations, genotype-specific dosing and mechanisms of drug action (the specific biochemical interaction through which a drug substance produces its pharmacological effect). This may eventually help physicians make the right individual patient choices for drugs that include pain relievers, antidepressants, antivirals, statins and blood thinners.
A number of barriers, which includes the lack of clear, evidence-based guidelines, need to be overcome before personalized drug therapy becomes a routine component of mainstream medicine. For now, pharmacogenetics testing is successfully being used in treatment of specific genetically influenced tumors, and for certain medications for cystic fibrosis, inflammatory bowel disease and HIV…important first steps in this promising field.

Defining Terms

  • Pharmacogenomics: A field of research focused on understanding how genes affect individual responses to medications.
  • Pharmacogenetics: Sometimes used interchangeably with pharmacogenomics, it’s actually a subcategory that refers to the role of genetic variation on response to a drug; can be inherited through the germline or acquired as in a tumor.
  • Pharmacokinetics: How a drug moves through an individual’s body, from absorption and distribution through excretion. Blood and urine tests determine where a drug goes and how much of the drug or a breakdown product remains after the body processes it.

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Hepatitis C Testing Recommended for All Baby Boomers

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It’s called ‘the forgotten virus,’ but after a sustained advertising campaign and years of strong recommendations for testing by the Centers for Disease Control it’s almost certain that the liver-damaging Hepatitis C will be remembered…and for good reason. All people born between 1945 and 1965 – the Baby Boomer years – are now advised to take a screening test for Hepatitis C virus, the most common bloodborne infection in the United States. The reason? Boomers, born in a time before universal precautions and infection control guidelines were fully established, are five times more likely to have Hepatitis C than other adults, but not likely to be aware of it, as symptoms lay dormant for years. Testing was first recommended for all Boomers in 2013, but less than 15 percent of this at-risk generation have heeded the advice, which means many who are infected remain unaware they carry a potentially fatal but very curable virus.
Below we dispel some of the misperceptions and the breakthrough treatments available today. Most importantly, we explain why scheduling a blood screening is a vital act of prevention, and one we encourage every Baby Boomer to take.

What is hepatitis C?

The common, chronic bloodborne infection known as hepatitis C is caused by the hepatitis C virus, and is a major cause of liver disease.

How does it happen?

The virus causes an inflammation that triggers a slow cascade of damage in the liver, with hard strands of scar tissue replacing healthy liver cells. The liver is no longer able to effectively filter toxins or make the proteins the body needs to repair itself.

Why is testing critical?

Hepatitis C can hide in the body for decades without causing symptoms, while it attacks the liver. Since most people don’t have warning signs of hepatitis C, they don’t seek treatment until many years later, when the damage often is well underway. Left untreated, hepatitis C can result in cirrhosis or liver cancer, and is the leading indication for liver transplant in the U.S. If treated, however, the vast majority of patients can be cured within a few months.

Did You Know?

80% – Of the 3.2 million people affected by chronic hepatitis C, almost 80% were born during the baby boomer generation

10.5 million – Out of 76.2 million Baby Boomers, the number who have been tested for hepatitis C

Sources: American Journal of Preventive Medicine, Centers for Disease Control

Why are Baby Boomers at particularly high risk for hepatitis C?

Once thought of as a disease primarily of drug users, contracted from sharing of needles, hepatitis C can also be contracted through inadequate sterilization of medical equipment and the transfusion of unscreened blood. Boomers grew up before the hepatitis C virus was identified in 1979, so it’s likely that many became infected through medical equipment or procedures before universal precautions and improved infection control techniques were adopted. Others may have been infected from contaminated blood before widespread screening nearly eliminated the virus from the blood supply by 1992.

What is the test for Hepatitis C?

A simple blood test for hepatitis C antibodies will indicate if you’ve been exposed to the virus at some point in your life. If you test positive, further testing will be done to determine if the virus remains in your body, how much is circulating and what specific strain or genotype you have. At least six strains of hepatitis C exist and treatment is based on the specific genotype. Other tests, including ultrasound, magnetic resonance imaging (MRI) and a liver biopsy can be performed to identify inflammation and see if any permanent scarring has taken place in the liver.

What treatments are available?

Today’s regimens of direct acting oral antivirals stop the virus from reproducing and clear hepatitis C from the body in a matter of weeks. These breakthrough drugs, first made available in 2013, represent a tremendous step forward in treatment, with a success rate upwards of 95% in those infected with the hepatitis C virus. Medication is targeted to the specific genotype of the virus, and most patients experience few side effects – a vast improvement over previous options of pegylated interferon and ribavirin which caused uncomfortable side effects and were effective less than half the time.

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The Zika Virus: Prevention is the First Line of Defense

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As the Zika virus continues to make headlines daily, it is essential to know who is at risk, how it is transmitted and most importantly, to understand strategies for prevention. Following are the latest findings on Zika, according to experts at the Centers for Disease Control and the World Health Organization.

How does Zika spread?

Most people get Zika from a mosquito bite, but it can also be passed through sexual contact, blood transfusion or during pregnancy to a fetus.  Zika is spread primarily by Aedes aegypti mosquitoes, which breed in areas with small pools of water, even as small as a coffee cup.  When a mosquito bites a person with Zika, the virus travels from its gut to its salivary glands and is then injected into the next human it bites.

Who is at risk?

Almost no one is immune to the virus.

How serious is the Zika virus?

If Zika is transmitted to a fetus during pregnancy, it can cause microcephaly, a birth defect that is a sign of incomplete brain development. Babies with microcephaly have extremely small heads, and the nerves connecting the eyes and ears to the brain may be permanently damaged. Therefore, pregnant women should avoid traveling to destinations with outbreaks of the virus, and should take extra precautions to protect themselves from mosquito bites. In addition, current research links Guillain-Barre syndrome (GBS), an uncommon sickness of the nervous system in which a person’s own immune system damages the nerve cells, to Zika; however, only a small proportion of people with recent Zika virus infection get GBS.

What parts of the US is Zika most likely to reach?

The Aedes aegypti mosquito is most common in Florida and along the Gulf Coast, but can travel much farther north in summer. In July, the first cases of Zika caused by mosquitoes in the U.S. (versus those cases acquired by people who traveled outside the country) were reported in the Miami area; in August several more were reported in Miami Beach. However, the CDC indicates clusters of cases are to be expected and does not signal the virus is spreading throughout the state. Experts say Zika is not as likely to spread in the U.S. as it did in Central and South America, because our living conditions are very different (air conditioning, closed windows in the summer and use of window screens) and tracking and treatment of infections is more effective.

What are the symptoms of Zika virus?

The illness is usually mild, lasting about a week with symptoms that include fever, rash, joint pain and red eyes. Only one in five people infected with the virus exhibits symptoms.

What can I do to protect myself?

First, decrease your risk of being bitten by a mosquito:

  • Use an EPA-approved insect repellant that contains DEET.
  • Wear clothing that provides coverage, such as long-sleeved shirts and long pants.
  • Treat clothing with permethrin, an insecticide.
  • At home, eliminate any areas of standing water outside that can provide a breeding ground for mosquitoes, including small containers, even a birdbath. Keep in mind that mosquitoes do not travel far once hatched, and will bite whoever is in close proximity.
  • If mosquitoes can reach where you are sleeping, put up a bed net.

Additionally:

  • Prevent transmitting or receiving the virus by practicing safe sex (use a condom).
  • When traveling, check travel advisories to identify areas with known cases of Zika, and avoid if possible. In the U.S., this now includes Miami-Dade County.

How is it treated? Is there a vaccine?

Considerable progress is being made in the development of a vaccine, but none is available yet, and health experts warn that it may take years before one is commercially available. Treatment today focuses on relieving symptoms and includes rest, rehydration, and acetaminophen for fever and pain.

For more information, check our website for updates and/or visit http://www.cdc.gov/zika/whats-new.html

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Inoculations

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Vaccinations are a vital part of preventive health maintenance beginning in infancy. Some vaccines that we received as children should be repeated in adulthood, and there are others that are specifically targeted for diseases that adults become susceptible to as they age. Additionally, some adults may not have received certain vaccinations as children and may now be advised by their physician to receive them.

The Centers for Disease Control (CDC) recommends guidelines for when inoculations should be administered. At the top of their list is an annual influenza vaccine. The Mayo Clinic advises that adults receive a flu shot annually in fall as protection against this potentially serious viral infection. However, there are some adults who, because of their health history, should not receive a flu vaccine. Every year this option should be reviewed with your physician.

In infancy and early childhood, a series of vaccinations are typically administered which include protection for many different diseases. One of the vaccinations that children usually receive is the five-dose DTaP vaccine – diphtheria, tetanus and pertussis (whooping cough.) The DTaP has replaced the older DTP vaccine which was known to cause immunization reactions. This vaccination is also recommended for children older than seven years of age who did not receive their complete five-dose series of DTaP.

For adults, it is commonly known that a tetanus booster is needed every ten years. Maintenance of this tetanus booster is extremely important because it protects against serious infections from common medical incidents such as cuts, puncture wounds and bee stings, to name a few. Most of us do not even realize that along with the tetanus vaccine, we receive the diphtheria vaccine as well. This inoculation is called a Td, and it protects against tetanus and diphtheria. However, with the more widespread outbreaks of pertussis in recent years, the CDC now recommends that protection against pertussis be included, at least once in adulthood. This vaccine is called the Tdap.

The CDC also recommends a single dose of the shingles vaccine for adults over age 60. Shingles occurs in 20% of people who have had chicken pox as a child. When a person contracts shingles, the chicken pox virus which was lying dormant reactivates, often causing severe pain, tingling, and possibly an itchy rash or blisters that resemble chicken pox. Only someone who has had chicken pox or, in rare instances, someone who has received a chicken pox vaccine, can contract shingles. For people with chronic illness, or those who are on immunosuppressant drugs, have severe allergies, or allergies to the components of the shingles vaccine, inoculation is likely not appropriate. Therefore, always discuss thoroughly with your physician before receiving any updated vaccines.

For adults who have never had chicken pox, the CDC does recommend being inoculated. While chicken pox might be uncomfortable and relatively harmless in children, adult chicken pox can pose more dangerous complications such as bacterial infection.

There is a vaccine which helps protect against types of bacteria called pneumococcus. This vaccine protects against illnesses including pneumonia, meningitis, the blood disease bacteremia, and middle ear and sinus infections. All of these are caused by pneumococcus bacteria. It is recommended that adults over age 65 receive the pneumococcal vaccine. This vaccine may also be recommended for younger adults who have a compromised immune system.

There are several other vaccines (such as Hepatitis A and Hepatitis B) that the CDC recommends only for adults with certain risks related to their health, job or lifestyle that put them at a higher threat for serious diseases. These risk factors should be discussed with your physician to determine what is appropriate for you.

If you are traveling outside the United States, there may be additional vaccines either required or recommended to safeguard you in your travels. Certain diseases, such as typhoid and yellow fever, are rare in the United States but are prevalent in other countries. Again, it is wise to check with your physician several months before leaving the country.

Many infectious diseases that once were serious health risks for infants, children and adults have decreased significantly or been eradicated in the United States. This is due to strong advocacy, general public education on the importance of maintaining vaccinations, as well as school requirements. Diligence in maintaining personal health records on inoculation history, combined with staying current on the recommended vaccinations helps prevent serious diseases, both for ourselves and the risk of passing on disease to others.

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