Precision Medicine- -Why should genetic testing now be included in each doctor’s diagnostic portfolio?


At The Private Harley Street Clinic, our goal is to move advanced genomics into mainstream clinical care, assisting clinicians to augment their diagnostic capability and pharmacological treatment optimisation. There is now convincing clinical data that demonstrates that by performing a specific panel of tests, each specialist can fine-tune and resolve diagnoses in difficult cases. The minister of health has unveiled new plans to offer new generation genome sequencing for all newborns in the near future. Shouldn’t we be thinking about offering this pioneering new technology to our patients now, resulting in everyone receiving personalised healthcare with tailor-made drugs and treatments?

Ever since the Human Genome Project was finally completed in 2001 at the cost of 3 billion dollars The holy grail has been to bring whole genome sequencing to the clinical domain. The restriction has hitherto been the high cost, but now, with the advent of new genetic sequencing technology, we are able to deliver clinical-grade testing at affordable prices to our patients and clinicians across the UK to make educated decisions about their patient’s health.

Scientific research on the meaning and clinical impact of DNA mutations is exploding at an exponential rate. Meanwhile, the technology of DNA sequencing has also progressed rapidly, meaning that we are now able to analyse all 22,000 human genes using a technology called whole-exome sequencing. This is significantly more powerful than the OTC tests like 23andMe that only look at DNA in a few places.

This detailed information is then matched with the latest scientific data to produce a comprehensive report, for example, examining all 1,000 cancer genes and every other known pathogenic mutation, compared to a typical over the counter (OTC) DNA test which just looks at 30-70 cancer genes.

In general, each study reveals about five pathogenic mutations meaning that approximately 50% of patients receive a life-changing discovery by identifying their risk for all diseases including heart disease, cancer, stroke and in addition rarer diseases.

At the Private Harley Street Clinic, we do not offer OTC genetic tests that only look at a few genes such as 23andMe and Color; instead, we offer clinical-grade testing up to 130X read depth with new genome sequencing technology. In addition, we can now provide this test using saliva rather than blood which results in cost-saving, faster turn around times, making it accessible to anyone regardless of their geographic location.

Our team includes consultant geneticists who are able to assist clinicians in interpreting the results and provide support for clinicians.

The DNA test offered by us is the gold standard, clinical-grade DNA test, that looks at the entire genome, where all 22,000 genes are analysed. This should not be confused with typical OTC DNA tests like 23andMe and Color which only test for 0.04% of the genome, we look at 100% of it. 

When sequencing your genome, there is an important concept known as coverage. The idea of coverage is similar to megapixels in your camera, the more megapixels your camera has, the more precise the image. The same applies to genome sequencing — the higher the coverage, the better the data quality. Coverage refers to the number of times the sequencing machine will sequence your genome. 

The clinical grade of the New Generation Sequencing allows for Copy Number Variant (CNV) evaluation enabling clinicians to make earlier diagnosis possible for even the most challenging conditions; improve disease diagnosis, monitoring, and treatment of rare neurological disorders. Exome with Copy Number Variant (CNV) evaluation is used when the conditions are so rare no diagnostic tests exist, targeting testing is impractical, or definitive tests are unavailable or non-informative. CNV evaluation can be particularly helpful to lower costs for physicians and patients, shorten a long, frustrating and often very costly ‘diagnostic odyssey’.

New Generation Sequencing empowers healthcare professionals with the tools to provide a more precise diagnosis and prescribe most effective treatments utilizing the power of pharmacogenetics, the report which we generate as an integral part of our service. We offer customised reports on the diseases of a clinician’s choice providing bespoke testing tailored to the needs of the practice and its patients. In addition, we are able to provide the benefit of state of the art imagining and connection to all other sub specialties in order to arrive at a complete solution for your patients.

We are now able to test for a panel of genetic mutations that are associated with diseases that have been difficult to understand whether there is a genetic predisposition, for example, autism, schizoaffective disease and alcohol dependency.

In psychiatry and neurology, our technique allows the detection of rare variants and de novo mutations. Because de novo mutations are not inherited from parents, sequencing the affected proband and the unaffected parents is a powerful tool to identify de novo mutations likely causing epilepsy. A genetic diagnosis can provide accurate prognostic information and even enable targeted therapy, depending on genetic mutation found. Genetic testing has an increasingly important role in the diagnosis and treatment of Epilepsy. Approximately 1% to 2% of epilepsies are monogenic, and the rest are polygenic, possibly caused by an excess of rare variants in epilepsy-associated genes. 

Schizophrenia has been associated with an overlapping set of Copy Number Variant loci, and recent studies confirmed that eight Copy Number Variants, in particular, del 1 q21, del 3q29, del 15q11.2, del 15q13.3, dup 16p11.2, dup 16p13.1, del 17p12, del22q11.21 were strongly statistically supported as risk factors for schizophrenia. Private Harley Street Clinic WGS reports include raw data VCF files for Copy Number Variants exposing ALL duplications and deletions.

In the genome-wide association study that included 3092 individuals from southern India, a genome-wide significant association with schizophrenia was observed on chromosome 8q24.3. Bioinformatic, cellular, and animal model evidence points to NAPRT1, a gene that encodes a key niacin metabolism enzyme, as the top gene within this locus. Given this gene's role in niacin metabolism and the evidence for niacin deficiency provoking schizophrenialike symptoms in neuropsychiatric diseases such as pellagra and Hartnup disease, these results suggest that the rs10866912 genotype and niacin status may have implications for schizophrenia susceptibility and treatment.

In dermatology for example, the NGS test allows differentiating between angiofibroma and tuberous sclerosis complex, or differentiating isolated oculocutaneous albinism from syndromic albinism which is present in many disorders such as Hermansky-Pudlak, Griscelli and Waardenburg syndromes. Moreover, genetic diagnostics provides prognostic information about visual impairment caused by oculocutaneous albinism. It also predicts the outcome of syndromic albinism in Griscelli syndrome, where type 1 syndrome is associated with severe neurological disease, and type 2 is associated with severe immunodeficiency.

In Cardiology differentiating from palpitations, seizure disorders, epilepsy and potentially lethal Long-QT syndrome, which can also be an underlying cause of sudden infant death syndrome; or the discovery of mild myocardial hypertrophy in an athlete (possibly related to athlete's heart or the onset of HCM). The DNA test, along with a cardiological inquest with the relatives, might offer crucial information for the management of such individuals. Even in patients with an established diagnosis of cardiac disease, diagnostic DNA testing might help to differentiate between several genetic causes (for example, in a patient with HCM) so that specific therapy could be applied (such as in Fabry disease), or genetic counselling could be modified (X‐linked inheritance in Danon disease), or specific follow‐up could be recommended (risk of conduction defects for PRKAG2 gene mutations). In addition, a patient with an apparently "sporadic" form of the disease may wish to know if the disorder is of genetic origin (such as ARVC) in order to determine the risk of transmission to offspring.

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The Private Harley Street Clinic

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