Is marfanoid habitus defined by the four ratio only?

Hi,

being a researcher myself (not a medical doctor), I find it difficult to find a source defining the features of marfanoid habitus. Most sources cite R.Grahame and the following:

Hand length : Height ratio > 0.11
Foot length : Height ratio > 0.15
Arm span: Height ratio > 1.03
Upper: lower segment < 0.89

There are additional signs, of course (high arched palate, arachnodactyly etc.) but it seems quite unclear what signs have to present to consider one a marfanoid or incomplete marfanoid. In Grahame's great paper (Arachnodactyly: A key to diagnosing heritable disorders of connective tissue), it is implied that one has to have all the four ratios abnormal to be considered marfanoid but it is not clear.

I have read that there are some other researchers and some directly from this area so I would appreciate any insight.

 

Hi @Blizna,
I was the junior member of the team when Rodney Grahame set up the hypermobility clinic at Guy's in 1978.
His definition of marfanoid habits is arbitrary and I doubt validated by any formal data. I also doubt that it is any clearer about requirements than you find it!
High palate, pectus excavated and arachnodactyly are features of Marfan syndrome. Whether they have any relevance to any other genetically determined hyper mobile states I very much doubt.

 

Hi Jonathan,
interesting, thank you! In his paper, he writes that with EDS or JHS, he often sees patients with both complete and incomplete marfanoid forms. From his statement "...marfanoid habitus is not defined exclusively by these ratios" I infer that he considers these four to be essential. Then there could be also high palate, scoliosis etc. but these need not to be present. I think it reflects the fact that to be diagnosed with Marfan you still need to have some cardiac involvement and/or eye and/or genetics. So you can have a fully expressed marfanoid habitus without MFS, as he stated with EDS and JHS. In his paper, he describes arachnodactyly to be common to all of these syndromes, including MFS, of course.
But I find it truly strange - so many authors work with the term "marfanoid", quoting possibly the only definition.

 

Rodney Grahame used to often see all sorts of things I never saw to be honest. I worked alongside him in various ways for thirty years and never got the impression he had any hard evidence for any of this stuff. It is popular with private practitioners who like to make diagnoses of EDS and suchlike. Unless you can find something I never heard from listening to a hundred lectures by Rodney I would assume this is all hearsay. Unfortunately there is a group of like minded physicians in private practice who get together to invent criteria for things like hEDS that include all sorts of things without any epidemiological basis. There is no reason to think that hEDS is a specific syndrome without clear genetic data or pedigrees. Definitions like this are more or less by definition circular in the absence of genes.

I wonder why you ask?

 

I have a question on a similar vein @Jonathan Edwards @Blizna. What if you are showing a few typical characteristics of Marfan syndrome but not all, and have at least one damaging mutation on FBN1, but no specific related heart issues seen (yet). According to this site FBN1 mutations are autosomal dominant.
https://ghr.nlm.nih.gov/condition/marfan-syndrome#genes

Could that lead to EDS type issues?.........

The ARUP test for Marfan is only a genetic sequencing test and even that test has the following limitations. So I guess the answer is "maybe" or "perhaps".

Source : https://ltd.aruplab.com/Tests/Pub/2005589

And as for ME/CFS connection the GARD site lists "Chronic extreme exhaustion" as a symptom. I also understand palpitations can be related to Marfan, a symptom I've seen some ME patients talk of.
https://rarediseases.info.nih.gov/diseases/6975/marfan-syndrome

If I was to guess an answer it would be you would have to know the levels of fibrillin-1 but is there such a thing available for clinical use? And even if it was, would it be reliable, as levels for many things in the body vary a lot.

 

What features do you mean? There are some very specific and some can be found in normal populations quite often. Myself, I have the wrist sign (I have a small frame), for example.