Genetic Testing Put Under the Microscope

August 13, 2019| By Dr. John O’Brien | Life | English | Français

Genetic testing is becoming more accessible and commonplace, with new genetic links to diseases regularly being identified. However, the many constraints on the use of predictive genetic tests in insurance means that the easy availability of direct consumer testing is an issue that the industry must consider very carefully.

Genetic science is actually relatively young. Gregor Mendel (1865) is credited with recognizing the transmission of dominant and recessive genes, and towards the end of the 19th century chromosomes were identified in dividing cells under light microscopy.

Messrs Watson and Crick revealed the structure of DNA in 1953 and our understanding of human genetics has progressed rapidly over the last 30 or 40 years. Genetic links to diseases have been recognised for a long time. A good example is haemophilia, which is carried by an X-linked recessive gene and therefore occurs almost exclusively in men.

Genetic tests can be used to give a risk assessment of the development of a disease in the future (predictive tests) or can help confirm an existing condition (diagnostic tests).

Genotyping looks at segments of DNA known as single nucleotide polymorphisms (SNPs). These are variations in sites of DNA identified as being associated with diseases. They are not necessarily causative and are not reliably predictive of the development of a condition.

With the development of next-generation technology, gene sequencing has become quick and relatively affordable. This technique allows the whole genome to be assessed - rather than looking at specific sites associated with previously described diseases.

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When assessing the risk of manifestation of a genetic trait, the mode of inheritance is clearly important. For a recessive condition to manifest, the individual must inherit the causative gene from both mother and father. If the condition is dominant, then one gene is sufficient. If the condition is a recessive condition, then the person carrying the gene is very unlikely to manifest the condition.

Understanding these concepts is important in interpreting information that may be provided regarding insurance applicants. The insurance industry is particularly concerned about predictive tests. Very few tests are 100% predictive since even if they do predict the condition, they don’t necessarily predict the degree of penetrance (the proportion of individuals carrying a particular genetic abnormality that will express the clinical symptoms associated with it) or expressivity (which measures the extent to which a given genetic trait is expressed).

A significant development for Life and Health insurers is that over-the-counter genetic tests are becoming increasingly available, and the results go direct to the customer as opposed to being recorded in any medical database. This not only creates the potential for anti-selection, but it also raises a number of concerns regarding the appropriate use of these tests.

From an insurance perspective, the use of genetic information is often limited by legislation or by agreement. In many if not most countries, the use of predictive genetic information to adversely rate an insurance applicant is not permitted. In the UK, there is a moratorium on the use of predictive genetic tests, apart from Huntington’s Disease (for insured amounts over GBP500,000).

It’s important to understand the different types of testing and their implications for underwriters. There are single gene mutations associated with serious illnesses, such as cystic fibrosis, but many conditions, such as ischaemic heart disease, are polygenic in origin. This type of condition in particular is often modified either positively or negatively by behavioural factors such as smoking, diet and exercise. Equally, it is advisable not to ignore a positive family history of disease because there is a negative genetic test.

Over a century ago Queen Victoria was accused of waging biological warfare on the royal houses of Europe after she passed on the haemophilia gene to two of her five daughters, Princess Alice and Princess Beatrice. The mutation was subsequently passed on to the royal families of Spain, Germany and Russia.

So genetics has long been a contentious topic - and no doubt will continue to be so.


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