This story in the Wall Street Journal about genetic testing shows the speed of changes in the medical community’s understanding of how and whether certain genes cause hereditary disease.
The article quoted Dr. Jodie Ingles, a geneticist from the University of Sydney in Australia who specializes in HCM and has published a recent article on the subject. Dr. Ingles said that 22 out of 33 genes comprising a genetic testing panel commonly used to test for HCM had either limited or no evidence of being disease causative.
These false positives are dangerous, according to Dr. Ingles, because invasive treatment decisions, such as implantable defibrillator (ICD) placement, may be based on this erroneous genetic information.
Though they can be lifesaving if appropriate, ICDs also have potential to cause harm to the patient. ICDs may cause infection, may inappropriately discharge, or they can be subject to lead complications which may necessitate additional surgeries.
You can read more about Dr. Ingles’ research and study results here.
A recent study published in Circulation suggests that clinical testing of kids who are first degree family members of HCM patients (i.e. siblings and children of those who have already been diagnosed with HCM) could be improved by starting testing at a younger age. And, genetic testing should further improve diagnosis and treatment for this group.
Almost 5% of children included in this study were diagnosed with HCM at the time of their initial screening. The majority of these children (72%) had not yet reached the age of adolescence. Childhood diagnoses were not that unusual in this sample: a childhood diagnosis was made in 8% of families that were screened.
Hence, this article suggest that regular screenings of youth in HCM families should start before age 10. Note that current ACCF/AHA Guidelines followed in the U.S. (published in 2011 and set to be updated next year) make screening before age 12 optional. The 2014 ESC guidelines followed in Europe recommend screening of children in HCM families from age 10 onward, unless there is a particularly bad family history or other factors which might call for heightened scrutiny.
A recent study by several HCM genetics researchers around the globe, led by Australia’s Dr. Jodie Ingles, found that 2/3 of genetic mutations previously reported to patients as HCM causative may actually NOT trigger HCM.
Dr. Ingles and the researchers looked at 33 genes frequently reported to patients as causative for HCM in commercial genetic tests. Surprisingly, of the 33 genes tested, only 8 were found to be definitively associated with HCM, 3 had moderate evidence to support their association with HCM and a whopping 22 or 66% of these genes were found to have limited or no association with HCM.
Mutations Definitive for HCM
Mutations with Moderate Evidence for HCM
These results should raise a red flag for consumers about genetic testing. Results of genetic tests require careful and informed interpretation. For accurate results, HCM patients should undergo genetic testing under the supervision of a genetic counselor with experience in HCM.
Not all genetic counselors are alike!
MyoKardia is collaborating with 23andMe, a genetic testing company which provides ancestry and health information directly to consumers, to create an online patient community intended to advance research efforts related to hypertrophic cardiomyopathy. The companies plan to allow 23andMe customers access to the latest information about HCM, as well as the opportunity to participate in research.
The companies will use a custom designed survey to collect baseline and follow-up data from HCM patients. They are hopeful that this collaboration will yield unique insights into HCM.
Research findings gained through the collaboration will be shared with HCM patients through the 23andMe platform. Currently more than 6,000 HCM patients are customers of 23andMe
More details of the collaboration can be found:
Press release from MyoKardia and 23andMe
DISCLOSURES: HCMBeat has received unrestricted educational grants from MyoKardia. Additionally, Cynthia Burstein Waldman of HCMBeat serves as a Patient Advisor on the Steering Committee for MyoKardia’s Explorer trial.
According to this study published recently in the Journal of the American College of Cardiology, whole genome testing may sometimes be used to identify the gene(s) responsible for HCM when targeted genetic testing (the type used in the clinical setting) has been inconclusive.
In particular, the study found the responsible gene(s) in 9 of 26 families (20%) in whom targeted testing had previously been inconclusive.
When used as the initial form of genetic testing, whole genome sequencing identified the responsible HCM gene in 5 of 12 families, or 42%.
According to this article in Wired U.K., a whole genome sequencing test costs about $600 and takes just a few weeks to complete. On the other had, the cost of data storage necessary to store such a large amount of collective data is, according to this article, prohibitively high.
If not for everyone, perhaps whole genome sequencing could be used in families where traditional genetic testing has proven inconclusive. Time will tell.
This recent article published in Nature discusses several real-life scenarios in which patients were mistakenly diagnosed with serious genetic cardiac conditions, including HCM, as a result of erroneous direct-to-consumer genetic testing.
These misdiagnoses directly resulted from misinterpretation of raw data by third party interpretation services that were working with raw data provided to them by direct-to-consumer genetic testing companies.
After medical testing, none of the patients discussed in the highlighted cases were ultimately found to have disease or be in need of medical intervention, though all underwent unnecessary medical testing and/or invasive procedures. Some even made radical lifestyle changes as a result of the erroneous genetic information.
This article demonstrates the unreliability of direct-to-consumer genetic testing, which has the potential to cause great upheaval to both patients and the medical system.
As always, patients seeking genetic testing should do their homework. Genetic testing for heart conditions is best when done by the experts – cardiac genetic counselors!
A recent editorial published in Circulation: Genomic and Precision Medicine suggests that current HCM screening protocols may need adjustment to account for recent findings by a study by researchers in the Netherlands. The Dutch study, published in the same journal, found that of 620 relatives of HCM patients who underwent genetic testing, 43% were found to be genetically positive for HCM, while 30% were diagnosed with HCM at the initial screening. 16% more went on to develop HCM during 7 years of repeated cardiac evaluation.
On the other hand, the 57% of relatives found to be genotype-negative were released from clinical HCM follow-up.
The Australian authors of the editorial, Semsarian and Ingles, note that current screening protocols would have failed to identify the 6 children (15%) who were diagnosed under the age of 12, half of which had a particularly malignant family history.
Additionally, few teens were diagnosed with HCM, which stands in contrast to current opinion that HCM is most likely to develop during adolescence. Indeed, most newly diagnosed family members were older than the age of 36, with 44% being over the age of 50.
Lastly, Semsarian and Ingles note their concern with general utilization of the Dutch practice of releasing a gene negative family member from serial follow up since the impact of all genes which have a role in causing HCM is not yet known while new genes which may cause HCM are still being identified.
Semsarian and Ingles also note that the Dutch patient sample differs from more typical patient populations found in the U.S. and Australia where causes of HCM are more diverse and cannot be easily tied to a specific gene.
An article entitled Psychosocial Impact of a Positive Gene Result for Asymptomatic Relatives at Risk of Hypertrophic Cardiomyopathy was published in this week’s Journal for Genetic Counseling.
The article focuses on the motivation for and the impact of HCM genetic testing on family members. The 32 participants in the study all encouraged family members to undergo genetic testing with the hope that the knowledge gained would benefit family members down the line. However, the study found that the psychological impact of a positive result, in the absence of overt disease, was highly variable. Some gene positive individuals perceived that they had an absolute risk of developing HCM, with substantial detriment to their lifestyle choices, while others were not at all affected by the result and made no lifestyle changes.
Continue reading “Continuing Genetic Counseling Helpful for Silent HCM Gene Carriers”
A recent Canadian study found that children with HCM who carry a single mutation in the MYH7 gene or who have multiple HCM-causative genetic mutations are at increased risk of major adverse cardiac events when compared to children who carry a single mutation in another gene.
Of the 98 gene positive children in this study, those with a MYH7 mutation or those with multiple mutations were more likely to need a myectomy or an ICD or to experience a sudden cardiac arrest or a heart transplant when compared to children with other HCM causative mutations.
The article also suggests that current screening protocols which recommend clinical and genetic screening for HCM beginning at age 12 may be insufficient.