Sunday, November 2, 2014

Secret Benefits to Thalassemia, Round 2: Email Inquiry

I get emails from people asking for me to diagnose them based on images of maggots that they found on their skin, a peculiar rash they've had for years, or something they found in their poop. I have to say, I love these emails. If anyone is worried about the NSA spying on their email activity, it should probably be me, because my inbox is full of stuff that could be considered private medical information, and I am not an MD.

But sometimes I get legitimate questions, like this one that I featured on my blog forever ago (don't worry, I always ask if they mind if I post their questions). Recently, I got a really interesting and smart question from an anonymous reader. The email said:
Dear Doc,  is there an immunity of reduction of Ebola with people who have beta-thalassemia? Or is it just the opposite, a more susceptible case for those with beta-thalassemia?
If you don't remember what beta-thalassemia is, or why it might be "beneficial" (I say this loosely, as it's not necessarily a good thing to have), feel free to brush up by reading this old post about it and it's relationship with malaria.

Image from the American Society of Hematology
To recap, thalassemia is a disease associated with globin gene mutations (both α- and β-globin genes can be mutated, yet α-globin mutations are most common). Since your α- or β-globin gene is recessively mutated if you have active Thalassemia, your red blood cells develop into malformed, or "sickled", cells, thus inhibiting their affinity to bind and transport oxygen (see image above for a great example). This lower affinity can cause extreme cases of anemia. In major cases, treatments such as chronic blood transfusion therapy, splenectomy, transplantation and iron supplementation are used. Thalassemia would make a great potential candidate for genome editing therapies that are still in the research stage (yes, I know that article is about hemophilia, but it's a good example).

So, why is this anonymous question a great one? Simply put, it doesn't really have an answer. There isn't any research being done to look into populations that aren't as affected by Ebola right now, as far as my searches have illustrated. This might be because most research that's being done is to either understand the physiology of the virus, to identify all possible vectors (yes, most evidence point to bats as the vector, but I'm still not convinced), or to come up with therapies/treatments and vaccines.

But the submitted question addresses an important point: thalassemia, specifically β-thalassemia is really prevalent in Nigeria (25% of the population are carriers for Sickle Cell Disease, while another 25% is hemizygous for the G6PD gene), and other parts of Africa. So, why isn't this being looked into? I can't answer that. I don't know. All I can say is maybe it isn't yet. I'm sure now that Ebola is in the spotlight, there will be a new emphasis on funding down the line for exploratory research.

In my fervent literature search to find an answer for the anonymous email, I did find that similar research has been done to look at the effects of thalassemia on hemorrhagic fevers (specifically Dengue Hemorrhagic Fever), mostly in Thailand and Southeast Asian countries. It turns out that patients with thalassemia don't necessarily have any higher risk, or even less of a risk (as seen with malaria), of getting hemorrhagic fevers, as my anonymous email inquiry asked. But, they do present differently, meaning their symptoms may seem different than infected people without thalassemia. Most normal (non-thalassemia) patients show signs of hemoconcentration (or an increase of solids in the blood), but patients with thalassemia present anemia (which is the opposite). This is the main symptom that presents differently, but its a really important one. Other symptoms also reference changes in AST and ALT levels, which illustrate the concentration of enzyme in the liver, heart and muscle cells, and can indicate liver function.

Hemoconcentration is really important during the diagnostic phase, and to track how the infection is progressing. So, if, instead, your patient is presenting with the exact opposite, it might lead to misdiagnosis. Also, if a patient with thalassemia, who is also infected with dengue hemorrhagic fever, is showing anemia, it needs to be watched. The three papers I linked to above talk about new suggested courses of action for patients with thalassemia, like frequent blood transfusions.

So, anonymous emailer, the answer is probably not. The biggest risk that thalassemia would give you is misrepresenting symptoms, which can lead to improper care. Yes, that can be really dangerous, especially with hemorrhagic fevers. But, luckily, if you have a high fever and other viral (standard) infection symptoms, your doctor will usually run other diagnostic tests (like an ELISA or PCR, etc.). That's why they always ask you questions about where you've been, what you've been in contact with, and other patient history questions.

This is definitely research that should be done, even if it starts with a retroactive epidemiology study.

Thanks for your question!

If any of you have other questions, feel free to email me at microscopic.blog@gmail.com!


2 comments:

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