Article No. 296
13 November 2019
A while back, a blog was published on this website titled “A rose by any other name …what’s the fuss ?”. It had resulted from some discussion about how the terms to which the abbreviations “ H” and “U” refer in aHUS were spelled differently .
”Haemolytic/ Hemolytic” and ”Uraemic / Uremic”
It lead to finding so many other differences in the way clinicians and researchers described the different facets of the same illness.
The article ended with aHUS translated into different languages. Something replicated in the design of the alliance’s t-shirt for 2019 aHUS Awareness Day!
Recently the alliance undertook its annual search for aHUS related research news presented at ASN’s Kidney Week. There were a number of items found, using the search term “aHUS”, which were interesting and were reported on.
One was about the different aHUS experiences found between women and men by a TMA Study Group from Vienna, Austria.
The Kidney Week “APP” allows further drill down using a search tool and through that other studies from that Vienna TMA Group were found.
But those studies were about “complement- Mediated Thrombotic Microangiopathy” or “cTMA” as the Vienna group termed it. One was about pregnancy outcomes and the other about transplant pregnancy for those diagnosed with cTMA. Those diagnosed cTMA would be more usually known as aHUS patients.
The audience at Kidney Week are renal experts,as are the speakers, the communication is between people who know about these things. Being more precise yet unconventional, as the Vienna Group had done, would not be confusing.
This educational conference was not for patients.
Yet the information in the studies was about patients and would be of interest to patients whether they have aHUS or cTMA. Pregnancy and/or Transplant are top topics of interest and feature in the Global aHUS Patients Research Agenda.
In the beginning all was called TTP. Then TMA came along as something different within TTP. Then HUS broke away from TTP too and then HUS split between typical ( e-coli infection causing ) and atypical ( everything else not TTP nor typical HUS related). So aHUS could include other TMAs. A distinction was then made between TMAs brought about because of defective complement regulation which got the “primary ” aHUS position and non complement aHUS became “secondary”.
Now we have cTMA!
But it is not going to be left at that. TMA seems be winning over TTP and HUS.
cTMA is an example of where all this is going. In the Vienna Groups studies reference is made to “p-cTMA” for pregnancy associated complement variant mediated Thombotic Microangiopathy.
The Vienna Group made clear this preference for TMA classification in an article which was published earlier this year. Fig 2 that article illustrates the basis for a new classification and nomenclature for diseases which share the same mechanical process of TMA.
17 different disease TMAs are placed on a line equidistant between TMAs which have susceptibility factors that are inherited at birth and those which are acquired in the patient’s lifetime. In all cases those diseases straddle the line because they all can be both inherited and acquired but each is then categorised by the dominant susceptibilities for the patient population .
aHUS is regarded as mostly an inherited Complement (variant) TMA, hence becomes cTMA, whilst ( typical ) HUS is seen as mostly an acquired infection TMA ( iTMA?).
TTP changes to both an inherited form ADAMTS13 variant TMA and an acquired version ADAMTS13-aab TMA. ( A13TMA and A13amTMA ?)
There is more to come as clinicians and academic researchers and their professional associations etc are thinking of reclassifying, recategorising and renaming and standardising what our disease will be called. There is no official body to approve such a move it will require consensus.
It could take years to get a consensus and patients will at best be like flies on the wall as the discussions and debates progress on what to call what we have.
The alliance’s “Rose” article may have been ahead of its time.
aHUS Patients and their organisations will need to rethink their place in, and scope of, their advocacy. A patient’s “discussion” perhaps.
In the meantime cTMA Awareness Day on 24 September is beginning to look more and more likely!
But when will Pregnancy TMA, Transplant TMA, DGKE TMA, CFH-aab TMA etc awareness days be?
But when those days do arrive, the 2019 aHUS alliance t-shirts could be become valuable collectors items!