The genetic material of any given individual human, except for identical twins, is unique. In April 2003, the Human Genome Project announced that researchers had sequenced 99% of human DNA and that humans have about 20,000 to 25,000 genes. Several regions of the human genome have yet to be sequenced, though, because we lack the technological expertise. Genetic testing allows scientists to look for genetic sequences that are associated with an increased risk of developing certain medical disorders. Hundreds of genetic tests already exist and more are rapidly being developed. The results of these tests are appearing as medical evidence in casualty claims with increasing frequency. Their presence radically increases the complexity of determining causation and assessing damages fairly.
More Genetic Tests, More Risk for Insurers
Many of the disorders predicted by genetic testing will emerge only if the individual is exposed to environmental conditions that trigger expression of the underlying genetic vulnerability. When the necessary environmental condition is a traumatic brain injury and that injury was caused by an insured, the claimant’s genetic vulnerability to the resulting medical disorder can become relevant to casualty insurance claims. In those instances, the claimant may allege that the insured’s actions are a proximate cause for the physical disorder even if that disorder will not emerge for many years. This is known as epidemiological risk. The fact that the claimant had a premorbid genetic vulnerability since conception is unlikely to serve as an effective defense for the insurer. It is well established in tort law that a particular vulnerability to harm does not excuse behavior, hence the well-known expression, “the tortfeasor must take his victim as he finds him.”
Epidemiological Risk: The sum of the factors controlling the presence or absence of a disease or pathogen.
Types of Genetic Testing
The term, “forensic” refers to the application of science to legal problems. When laypersons think of genetic testing they commonly think of forensic testing which uses sequences of genes in DNA to identify a suspect in a criminal matter, identify catastrophe victims, or establish paternity. Forensic testing is not used to detect genetic mutations associated with medical disorders.
Other people may think of legally mandated genetic screening performed on their newborn child to identify disorders like phenylketonuria, a medical disorder that can cause seizures and severe mental retardation unless dietary restrictions are observed beginning at birth.
Traumatic brain injury claims rely on predictive and presymptomatic types of testing. These genetic tests seek genetic mutations associated with medical disorders that appear long after birth, often years after the cause of action. These tests can be performed on a sample of blood, skin, hair or other tissue, but typically a buccal smear is used which involves using a small cotton swab to collect a sample of cells from the inside surface of the claimant’s cheek.
Types of Genetic Testing: Prenatal, newborn screening, diagnostic, carrier, predictive and presymptomatic, forensic.
Risks Associated with Genetic Testing
In the United States, the Genetic Information Nondiscrimination Act was signed into law on May 21, 2008. It prohibits group health insurance plans and health insurers from denying coverage to a healthy individual or charging that person higher premiums based solely on a genetic predisposition to developing a disease in the future. The legislation also bars employers from using individuals’ genetic information when making hiring, firing, job placement, or promotion decisions. The law does not protect insurers from the genetic epidemiological risks associated with an injury caused by an insured.
Many of the risks associated with genetic testing involve the emotional or social consequences of the test results. People may feel angry, depressed, anxious, or guilty about their results. In most cases, however, the results provide only limited information about the risks of developing a disorder. The test often can’t determine if a person will show symptoms of a disorder, how severe the symptoms will be, or whether the disorder will progress over time. Another major limitation is the lack of treatment strategies for many genetic disorders once they are diagnosed.
Alzheimer’s Disease from Motor Vehicle Accidents?
The combination of new knowledge from genetic testing and the legal possibility of demanding compensation for epidemiological risks are leading to some new and interesting claims. For example, in a recent case a 24-year-old victim of a motor vehicle accident alleged that she should be financially compensated for her increased risk of developing Alzheimer’s Disease (AD) later in life. She alleged, based on her genetic test results, that her mild traumatic brain injury had heightened her risk. The foundation of her argument was that genetic testing indicated that she had one copy of the apolipoprotein-E-4 (ApoE4) gene and that increased her likelihood of AD subsequent to a brain injury.
The ApoE gene is on chromosome 19. Every human has two copies of it and each member of the pair can be in one of three forms: ApoE2, ApoE3, and ApoE4. The ApoE4 allele has been implicated in the nervous system’s response to injury and AD, but the relationship is complex and not nearly as direct as was implied in the above referenced case.
He Loves Me, He Loves Me Not
Although 40-65% of patients with AD have at least one copy of the ApoE4, at least a third of patients are ApoE4 negative and some patients with two copies of ApoE4 never develop the disease. Among ApoE4 carriers, another gene, GAB2, is thought to further influence the risk of getting AD.
Longitudinal studies published in major medical journals over the past decade have concluded the following about the risk of developing AD after a traumatic brain injury:
- Data from the Nun Study suggests that the risk for AD is largely established by early adulthood, and events that occur later likely play only a small role in causation.
- The Rotterdam Study looked at 6,645 persons and found that mild head trauma, even if it was recurrent and resulted in a loss of consciousness, was not a major risk factor for dementia or AD and the ApoE4 gene did not modify the relationship.
- Intercultural epidemiological findings suggest that analogous to cardiovascular diseases, ApoE4 requires a high fat diet and sedentary lifestyle to manifest as an Alzheimer’s disease risk factor.
- A study of 4,615 Canadians found head trauma was not associated with the risk of developing AD.
- A pooled analysis of four European population-based prospective studies, followed for 28,768 person-years, found that a history of brain trauma with unconsciousness did not increase the risk of AD.
- Autopsy-based studies have found subjects lacking ApoE4 to be at increased risk of AD only if they have suffered severe brain injury.
- The often-cited study of World War II veterans resulted in “inconclusive” results for the association between mild brain injury and AD, and a possible influence for moderate and severe brain injury.
- A study of 2,333 persons with probable or definite AD and their 14,668 family members at 13 centers in the USA, Canada, and Germany found brain injury is a risk factor for AD. The magnitude of the risk was proportional to severity of the brain injury and greater among persons lacking ApoE4 compared with those having one or two ApoE4 genes.
Research published in 2008 found that in contrast to earlier studies, carrying the ApoE4 gene may have a protective influence on long-term outcome following traumatic brain injury. Dutch researchers found that ApoE4 carriers had a significantly better global functional outcome on the Glasgow Outcome Scale one to three years after injury than those without the ApoE4 gene. Other studies have found that the ApoE4 gene results in better neuropsychological test performance.
A Whole New World
Taken together, the above studies indicate that even when considering only a single variant of a single gene on a single disorder in response to a single injury type, there are conditions in which the genetic variant is health promoting and others in which it has a deleterious effect on the claimant. Obviously, this opens up possibilities never envisioned in response to fender bender claims in past years. As the number of genetic tests swells and our knowledge of the genetic risk factors associated with medical disorders increases, more possibilities will confront the claims examiner. In many cases, the assistance of a consultant familiar with the latest genetic research will be necessary for the equitable resolution of these new injury claims.
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