Today, in our Gilmore Health Q&A Series we discuss genetic diseases with Dr. Sony Sherpa as they are a biological, and financial burden. They may only affect a single member of the family physically but can be socially and mentally draining for the rest of the family.
Genetic diseases are a group of diseases that can pass from parents to their children, causing disease with varying degrees of severity. Genetic diseases are relatively common, making up to 14% of all pediatric discharges. Furthermore, they cost upwards of 50 billion dollars yearly, putting a financial strain on the families of affected individuals
Here we talk more about genetic diseases with Dr. Sony Sherpa, to get more insight into these diseases with the aim of understanding them further.
What are genetic diseases? Aren’t all diseases genetic, technically?
Dr. Sony Sherpa: Well, yes. As researchers learn more about diseases and the different components to them, they have concluded that almost all diseases do have a genetic component to them. However, a genetic disease is a disease that occurs as a result of a change in a person’s DNA. This change or mutation can cause disease of varying severity depending on the extent of damage done to the DNA.
So, when you say all diseases have a genetic component, that means all diseases arise from this change in the DNA?
The short answer is yes. The long answer is that most genetic diseases are diseases arising from mutations in one single gene. But most diseases, in general, are what we call multifactorial, or complex disease. Now, these diseases can arise due to environmental factors, genetic factors, occupational hazards, or iatrogenic reasons. Hence, the name; multifactorial. The genetic component of these diseases, albeit a small part, is a very important part in the understanding of these diseases.
Could you perhaps elaborate on this with an example?
Yes, sure. Diseases like sickle cell or Cystic fibrosis are genetic diseases. They arise from a mutation in a single gene and have a clear cut inheritance pattern. On the other hand, there are diseases like diabetes mellitus type 2 or cardiovascular diseases that are polygenic in origin. Not just that, the inheritance pattern of these diseases isn’t understood much either. While many studies are looking into it, it’s going to be a while before we understand the hereditability factors of these complex diseases.
Can complex diseases be passed on from parents to their children? Is it seen usually, or is that one of the many things yet to be discovered?
Complex diseases usually cluster in families, but as I mentioned before, there is no clear explanation for that phenomenon yet.
Alright, then how do single gene-genetic diseases pass on from parents to offsprings?
That we have an understanding of. At least the basics. There are five inheritance patterns of single-gene genetic diseases, namely; Autosomal Dominant, Autosomal Recessive, X-linked Dominant, X-linked Recessive, and mitochondrial. However, the pattern of inheritance differs for each disease.
All single-gene genetic disorders follow one of these five inheritance patterns. What’s the difference between them, in simple terms? What is the basis of separation between these patterns?
Well, it is pretty interesting. Inheritance patterns tell us the origin of the genetic disease, the genotype it has and it can mathematically estimate the percentage risk that a child born to two carriers/patients will have the disease. The genotype of the genetic makeup decides the phenotype or physical appearance of the disease for everyone. The genotype can be realized from alleles that are received from both parents. These alleles can recognize the traits and then classify the inheritance into dominant or recessive. Basically, if a disease requires a mutation to be present on both alleles, then it is recessive. But if it can be pathological with just one mutated allele, then it is dominant.
What about the mitochondrial inheritance pattern then?
Some books and studies still do not accept mitochondrial inheritance patterns to be one of the main inheritance patterns. But regardless of that, it is an important topic. Mitochondria of the cell have their own DNA. And this DNA is passed down from mother to offspring. It’s always inherited from the mother. Therefore, any mitochondrial disease would also be purely maternal in origin.
Since these diseases are inherited with alleles on genes and are due to mutation in the DNA, how does one diagnose these diseases? I am assuming it would require a lot of genetic karyotyping and testing? That sounds like a very tedious and complicated process.
Dr. Sony Sherpa: Yes and No. Yes, genetic diseases are very much gene-related as the name suggests, these diseases are diagnosed mostly through genetic testing. OR better yet, the diagnosis is usually suspected through clinical presentation and laboratory testing, it is confirmed through genetic testing.
Genetic testing is not tedious, and a very simple procedure. It can be done in one of three ways; cytogenetic genetic testing wherein the entire chromosome is analyzed and studied, biochemical genetic testing which includes testing the proteins and the biochemical reactions associated with them, and lastly, molecular genetic testing for analysis of small DNA mutation.
You mentioned suspicion of a genetic disease. What araises suspicion of a genetic disease, what are the symptoms that can be alarming?
The suspicion of genetic diseases depends on physical examination, family, and personal history. The red flags for a doctor usually include positive family history, history of miscarriages or stillbirths in the mother of the affected individual, presence of clinical signs characteristic of a genetic syndrome, and so on. If the mother admits to being exposed to teratogens, whether occupational, alcohol, or certain medications, they may also alert the physician towards the presence of a genetic disease or syndrome. Usually, there are mandatory screening tests for certain genetic conditions in most countries.
Basically, a genetic disorder can be the differential diagnosis of many symptoms an individual might present to the hospital with?
Dr. Sony S: Well, yes. Pretty much so.
And how would someone affected by a genetic disease get treated for these conditions? It would seem like they would need a gene treatment plan.
Treatment of genetic diseases obviously depends on each disease and what it entails. For genetic syndromes, the plan is usually to prevent its progress with medications all the while treating the symptoms of the disease. Depending on the symptoms, appropriate therapy may be applied.
Genetic diseases are a life-long process, and they require a very healthy lifestyle and strict adherence to medical therapy and surgical therapy if needed, for a chance to have a good quality of life. The main aim is to increase the quality of life and increase the life expectancy of affected individuals. It mostly is symptomatic therapy of sorts.
That explains it. Thank you for your time.
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