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Question on "rare" vs "common"

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deleted862527

    I was reading up on the etiology and prevalence of a certain hematologic disorder. The prevalence of this disorder was 1 in 200,000 --- but yet, I read that the disorder is 'common'. How exactly is this common when statistically speaking, 5 people per million get diagnosed? I also researched about a certain rare, aggressive stomach cancer where the prevalence was 1 in 50, and the doctor I talked to said it was very rare. I did not question the Doctor, because duh he knows more than I do and I'm just trying to get into medical school---but I am just looking for clarification.

    Thanks!
     

    Matthew9Thirtyfive

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      The Rare Diseases Act of 2002 defines a rare disease as affecting fewer than 1 in 1500. But in practice, these definitions are not standardized. So someone might say something is rare because they don't see it that often themselves, yet it is actually fairly common nationwide or worldwide.
       
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      efle

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        There must have been some kind of miscommunication at some point, I don't think even a super-specialized doc at a tertiary center would call a disease "common" when only 1000-2000 people in the nation get it
         
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        deleted862527

          There must have been some kind of miscommunication at some point, I don't think even a super-specialized doc at a tertiary center would call a disease "common" when only 1000-2000 people in the nation get it

          It's no joke. I don't get it either. The specialists I talked to (2 of them) say this subtype is "common", when the prevalence of it is 1 in 200,000.
           

          hurtem&healem

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            It's no joke. I don't get it either. The specialists I talked to (2 of them) say this subtype is "common", when the prevalence of it is 1 in 200,000.
            Could they have meant, "of the patients I see, this subtype is relatively common." i.e., if you're already looking at a somewhat rare cancer, if 10% of their cases were this subtype, it would be common for them but very rare in general.
             
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            Med Ed

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              I was reading up on the etiology and prevalence of a certain hematologic disorder. The prevalence of this disorder was 1 in 200,000 --- but yet, I read that the disorder is 'common'. How exactly is this common when statistically speaking, 5 people per million get diagnosed?

              Name the disorder and some clarity might emerge.
               

              Raryn

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                I was reading up on the etiology and prevalence of a certain hematologic disorder. The prevalence of this disorder was 1 in 200,000 --- but yet, I read that the disorder is 'common'. How exactly is this common when statistically speaking, 5 people per million get diagnosed? I also researched about a certain rare, aggressive stomach cancer where the prevalence was 1 in 50, and the doctor I talked to said it was very rare. I did not question the Doctor, because duh he knows more than I do and I'm just trying to get into medical school---but I am just looking for clarification.

                Thanks!
                The incidence of gastric cancer in general is 7.3 per 100,000. No way there's an aggressive stomach cancer that has a prevalence of 1 in 50, unless we're talking about it being 1 in 50 of gastric cancers.
                 
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                calivianya

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                  I'd say that the physicians in question are talking about their personal interactions with the disease, not the prevalence of the disease in the population.
                   
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                  longhaul3

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                    In genetics, "rare"usually means that a second mutation is unlikely to come from outside of the family in question, i.e. that you can assume that no one from outside the family is a carrier. "Common" can therefore refer to diseases like CF, which is rare compared to diabetes, but an affected child can be born to unrelated carrier parents.
                     
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