So is aHUS a rare disease? It is rarer than rare!

Is aHUS a Rare Disease?
Good question when Rare Disease Day 2017 is nearly upon us.Well by the definitions of what constitutes a rare disease, aHUS is rare disease.
Definition(S) !!?
Yes there are many definitions for the term rare disease and there is no worldwide consensus how RARE is RARE.
So how do they define it.
The most common way is by setting a threshold for the  number of people surviving and living with a disease. In the USA it is rare disease if less than 200,000  of the population are affected by the disease. Japan sets the threshold as less than 50, 000.  Others like Europe set the threshold as whether there is less than so many of the population. In Europe a disease is rare if there is less than 5 in 10,000 of the population affected .  So each is different USA is about 1 in 1500, Japan is about 1 in 2500 and Europe it is 1 in 2000.
What are the other ways?
Well in some cases the disease also has to be life threatening or chronically debilitating or inadequately treated as well as within a stated number threshold as is the case in Europe.
Regardless of all this is aHUS a rare disease because it is treated with an Orphan Drug
aHUS is treatable with a drug which has been designated as an orphan but orphan drugs can be designated as orphan even if the disease is more common than those defined as rare using the thresholds above. Orphan has become almost synonymous with rare but it is a term which relates to whether Pharma have “adopted” a disease for treatment. Eculizuab was given Orphan status because there was no adequate treatment for aHUS, so it can also be described as an orphan disease, indeed it is ultra-orphan.
Indeed a drug can be called Ultra-orphan if it used to treat a disease which only affects less than 1 in 50,000 ( or in the USA affects less than 2000 people) but that is an informal sub category ,not a legal definition. There are various  estimates of the prevalence of aHUS but it is likely to be less than  0.2 people per 50,000. So an aHUS patient is being treated by an ultra-orphan drug and so could be said to be an  ultra-orphan disease which is very, or extremely, rare by all rare disease standards.
So aHUS is  rare  disease and SOME then!.  An ultra rare orphan disease.
Absolutely so join in with Rare Disease Day 2017 and make a noise about how rare aHUS is.
Those on-setting with aHUS for the first time this year are truly one in more than a million .
To read some rare disease  research on rare disease terms and definitions click here 

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