Having watched a charming video of 'Carpool Karaoke' with mothers and children on the World Down Syndrome Day website, in preparation for the twenty-first of this month, I noticed that 'Down's Syndrome' has been changed to 'Down Syndrome'.

Such is the wealth of information online about the syndrome that I have struggled to find among it a reason for the change.

Vivid memories remain from childhood of a remarkable young man who achieved much despite his condition but I have always called it 'Down's' and I assumed it was named after a doctor involved with its documentation. But the change makes that seem unlikely.

Can anyone help?

  • 5
    Loosely related, but it provides some interesting information:What causes the euphemisation of medical terms?
    – Mari-Lou A
    Commented Mar 18, 2018 at 16:52
  • 5
    Straightforward phonetic assimilation: Down's Syndrome contains a /zs/ sequence from the 's S segment. In normal speech, such a sequence will delete the /z/ naturally, since it's simply a voiced version of /s/, so just turning off the voicing right after /n/, instead of in the middle of the sibilant, turns out to be the natural way that Americans, at least, pronounce it. As for spelling, that already lags behind pronunciation, but it's catching up. Commented Mar 18, 2018 at 16:53
  • 3
    Alzheimer disease or Alzheimer's disease? similar answers but the question is different.
    – Mari-Lou A
    Commented Mar 18, 2018 at 17:00
  • 3
    I think the reasons are semantic, not phonological.
    – Lambie
    Commented Mar 18, 2018 at 17:26
  • 10
    Point to note: it has only morphed into “Down Syndrome” in American English. In British English, it has always been “Down’s Syndrome”. Commented Mar 19, 2018 at 0:58

2 Answers 2


Some relevant articles: "Whose name is it anyway? Varying patterns of possessive usage in eponymous neurodegenerative diseases", by Michael R. MacAskill and Tim J. Anderson (2013), and "The synthetic genitive in medical eponyms: Is it doomed to extinction?", by John H. Dirckx (2001).

The abstract to the MacAskill and Anderson article says

The PubMed database was queried for the percentage of titles published each year from 1960–2012 which contained the possessive form of Parkinson’s (PD), Alzheimer’s (AD), Huntington’s (HD), Wilson’s (WD), and Gaucher’s (GD) diseases (e.g. Huntington’s disease or chorea vs Huntington disease or chorea). Down syndrome (DS), well known for its changes in terminology, was used as a reference. The possessive form was nearly universal in all conditions from 1960 until the early 1970s. In both DS and GD it then declined at an approximately constant rate of 2 percentage points per year to drop below 15%. The possessive forms of both PD and AD began to decline at the same time but stabilised and have since remained above 80%, with a similar but more volatile pattern in HD. WD, meanwhile, is intermediate between the DS/GD and PD/AD/HD patterns, with a slower decline to its current value of approximately 60%. Declining possessive form usage in GD and DS papers has been remarkably uniform over time and has nearly reached completion. PD and AD appear stable in remaining predominantly possessive.

Here is Figure 1, which presents the relevant results in graphical form:

Figure 1

The results summarized in this figure don't differentiate between different varieties of English. (Although PubMed is "developed and maintained by the National Center for Biotechnology Information (NCBI), at the U.S. National Library of Medicine (NLM), located at the National Institutes of Health", the database contains literature that was published in the UK as well as literature that was published in the US.) But there do seem to be notable differences in usage between American English and British English in this area. MacAskill and Anderson analyzed the use of "Parkinson's disease" vs. "Parkinson disease" in UK-based vs. US-based journals general journals and found evidence that the rise of the latter form in US-based journals was influenced by changing editorial preferences. It seems probable that the rise of "Down syndrome" had a similar cause.

A quick look at "Down's syndrome" vs. "Down syndrome" in the Google Ngram Viewer does support the point that has been brought up in comments about the ratio of "Down syndrome" to "Down's syndrome" being higher in the US than in the UK. However, both forms do seem to exist in both varieties of English.

American English:

ratio of "Down" to "Down's" at around 4.6/1 as of 2008 British English:

ratio of "Down" to "Down's" at around 1.2/1 as of 2008

Possible phonetic pressures for the change?

John Lawler suggested in a comment beneath the question that certain phonetic features of "Down's syndrome" may have contributed to its becoming less preferred relative to "Down syndrome":

Down's Syndrome contains a /zs/ sequence from the 's S segment. In normal speech, such a sequence will delete the /z/ naturally, since it's simply a voiced version of /s/ [...] spelling [...] lags behind pronunciation, but it's catching up

This seems somewhat plausible, but the initial dominance of the spelling with 's, and the data in the MacAskill and Anderson article showing a parallel decline in the frequency of Gaucher's disease vs. Gaucher disease, indicate that a phonetic explanation is probably not the whole story even if it may have some applicability. While it seems hard to estimate exactly how much of a role phonetics may have played in the development of the spelling Down syndrome vs. other factors, I'd guess that other factors were actually more important.

Dirckx makes a similar suggestion on p. 19, saying

[the form without the suffix -'(s)] is often chosen for proper names ending in s (Colles fracture, Graves disease) because, as mentioned earlier, many speakers pronounce Colles’s and Graves’s exactly like the uninflected (nominative) forms of the nouns. To a lesser degree, the form may be preferred before words beginning with an s or z sound, since the inflectional s of Marfan’s syndrome and Looser’s zones tends to be lost in speech.

  • 1
    WRT Parkinson vs Parkinson's - does that also include Parkinsonism (which we use in our published material, and is used a lot of source/references) in the reckoning, because that might affect the statistics.
    – HorusKol
    Commented Mar 19, 2018 at 0:08
  • 10
    @HorusKol I wrote that paper, so can answer perhaps... We analysed idiopathic Parkinson's disease (IPD) specifically, and not the variety of conditions that share some of its symptoms. i.e. parkinsonism (note the lower case 'p') is a different concept to IPD, medically and grammatically. It relates to symptoms similar to those seen in IPD but that have some other cause (e.g. stroke, the atypical parkinsonian conditions (again, note the lower case 'p'), and so on). Thus parkinsonism is a common rather than proper noun: it is a term derived from Dr Parkinson's name. Commented Mar 19, 2018 at 1:07
  • 3
    @sumelic "I don't know to what extent these results might be applicable to only certain kinds of English.": in the other figure in that paper, we depict differences between UK/European journals and US ones, and there are definitely differences. The change was likely driven by an NIH recommendation in the early 1970s and has been more strongly adopted in US journals, although this has fluctuated over time given specific editorial practices. Very nice to see your independent confirmation via Google Ngram Viewer. Commented Mar 19, 2018 at 1:20
  • 2
    @MichaelMacAskill: Ah, thanks, I evidently still hadn't read through all of it! It's great to get some comments from you as an author of the paper.
    – herisson
    Commented Mar 19, 2018 at 1:23
  • 3
    @sumelic Great to see your efforts in answering this question so fully, using quantitative evidence. Clicked on this question out of interest and was pleasantly surprised to see our work being used too. Cheers. Commented Mar 19, 2018 at 1:40

This is a general phenomenon and is not limited to Down Syndrome. Here is a reasonable explanation from a doctor:

The medical profession has urged since the 1970s the dropping of the possessive S at the end of disease names which were originally named after their discoverers (“eponymous disease names”). The possessive is thought to confuse people by implying that the persons named actually had the disease. Thus “Ménière’s syndrome” became “Ménière syndrome,” Bright’s disease” became “Bright disease” and “Asperger’s syndrome“ became “Asperger syndrome.”

But the public has not always followed this rule. “Alzheimer disease“ is still widely called “Alzheimer’s disease” or just “Alzheimer’s.” Only among professionals is this really considered a mistake.

disease naming

Wikipedia has a full-list of disease names, and all follow the rule of not using the apostrophe s.

  • 54
    Just to be clear, it is the American medical profession that has been urging this since the 1970s. The medical profession in the rest of the world is does not urge this. All of the medical professionals I know in the UK refer to "Down's Syndrome", as do the few that I know in other countries.
    – Spudley
    Commented Mar 18, 2018 at 20:54
  • @Spudley Right you are.
    – Lambie
    Commented Jun 16, 2018 at 21:33
  • @Spudley It probably has something to do with the fact that Lou Gherig actually had Lou Gherig's disease (amyotrophic lateral sclerosis), and the Legionnaires actually had Legionnaires' Disease (pneumonia caused by Legionella bacteria), and both cases involved prominent Americans
    – No Name
    Commented Jun 7, 2023 at 11:56

Your Answer

By clicking “Post Your Answer”, you agree to our terms of service and acknowledge you have read our privacy policy.

Not the answer you're looking for? Browse other questions tagged or ask your own question.