When I ask a patient about their family history, I do so to offer the most accurate risk of disease I can for them or their children. So when a patient says, “My relative has ‘something, like Down syndrome’” I inevitably cringe inside.
For me to provide accurate risk assessment I, like all genetic counselors, need to know who has what in a family. Where, how, and when that relative was diagnosed is icing on any GC’s cake.
This is because:
The closer in the family tree the affected person is to a patient, the higher the risk. I tend to worry less when a patient’s cousin’s child or great-aunt is affected by a condition. My concern increases as that relative becomes their cousin, aunt, or any first-degree relative, as the last group shares 50% of their DNA with the patient. How many relatives are affected can also make a difference. While 90% of cancer is sporadic, in other words not linked to a hereditary cancer syndrome like Lynch syndrome or hereditary breast and ovarian syndrome, the more relatives who are affected, the higher the genetic risk, generally speaking.
What the genetic condition is informs us of its inheritance. If a female patient reports that one maternal cousin has Down syndrome and it was confirmed by genetic testing that the condition wasn’t related to a chromosome translocation, I’m going to tell the patient that their risk of having a child affected is no greater than the patient’s age-related risk and would not recommend a chromosome analysis on the patient.
If she reports that two maternal cousins and her last miscarriage were found to have a translocation involving chromosomes 21 and 14, I’m going to tell her that chances are most likely increased to a point of 10-15% per pregnancy but I recommend confirming that by starting with a chromosome analysis on the patient.
Saying it is ‘something, like Down syndrome’ can mean anything from the relative has a degree of intellectual disabilities or physical findings that could be due to a prenatal exposure like alcohol OR any one of over 6,000 genetic conditions currently known OR a different chromosome change.
Where and how was the diagnosis made can validate the medical history. A patient reporting that their grandfather was diagnosed with Alzheimer’s disease by a neurologist is very different from a diagnosis from his grandfather's primary care provider. Diagnosis by a medical specialist who has been trained to look for the signs and symptoms of a given condition is imperative. Were neurological exams, cognitive, functional, and behavioral tests, depression screening and mood assessments, and brain imaging conducted, or was this diagnosis through a basic medical history assessment?
Finally, at what age (i.e. when) was a diagnosis made plays into risk assessment. Every year about 805,000 Americans have a heart attack, but most of them are not under the age of fifty at the time. Most common diseases – think heart disease, diabetes, autoimmune conditions, cancer, and hearing loss – are multifactorial. This means that both a whole lot of genetic factors and a whole lot of environmental factors combine to contribute to the occurrence of a disease. If a person has a younger age of onset, there has been less time for those environmental factors – be it diet, lack of exercise, exposure, etc., to contribute to their condition, putting more weight on the genetic aspect.
So, in preparing to talk with a genetic counselor, do both of you a favor and get the most out of your visit – get the Who, What, When, Where, and How before you go.
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