Dr Child's Casebook: Appearances Can Be Deceptive – The Relative Anomaly

Some medical conditions hide in plain sight, others are writ large. A study of tallness in Marfan people found their mean height was above the 95 percentile for the general population by their third birthday. Marfan is a visible syndrome, synonymous with long slender limbs. Yet appearances can be deceptive. There are those who are not tall compared to the general population, and their height should not be used to rule out Marfan syndrome. Conversely, there are those who appear marfanoid and do not have Marfan syndrome but something that mimics it. This latter has been a constant in our helpline. In our new two-part Casebook series, Dr Child discusses what constitutes the definitive diagnosis of Marfan syndrome.

Q: My whole life I've been pretty skinny. I'm about 5'10/5'11 and weigh about 145lbs (when all of this started I was probably closer to 125lbs). About 6 years ago I first discovered Marfan Syndrome (MFS). I found out about it when National Basketball Association soon-to-be Draftee Isaiah Austin was diagnosed with it, ruling him out of the draft and forcing him into an early retirement. Naturally, I went straight to my phone and googled everything about MFS and began on a slippery slope which would eventually lead me to write this I do have a few symptoms of MFS; long fingers, toes; mild pectus excavatum, relatively low arches in my feet and skinny arms / legs. These are all symptoms which of course are relative. In actuality, my fingers and toes are not much longer than the average male, and almost mirror my parents' hands. My pectus is a relatively mild case which causes no real discomfort. These symptoms, however, *are* common with people who have MFS.

A: I am so pleased that you wrote, because the diagnosis and management of Marfan syndrome has improved greatly. Basically, you need a follow-up genetic appointment for further counselling and testing. The reason for this is that there are many conditions that overlap with Marfan syndrome and can mimic it. As well as doing a very careful updated examination of yourself, the regional genetics unit can now offer a DNA test looking at your blood sample to study the Marfan gene itself. If a mutation (gene error) is found, this probably means you have mild Marfan syndrome. The test is positive in 97% of Marfan patients.

If, on the other hand, no gene error is found, then you almost certainly do not have Marfan syndrome.

In order to make a diagnosis of Marfan syndrome, we need classical changes in two out of three systems (eyes, heart, skeletal). Certainly, in the past, your eye examination and ultrasound picture of your heart (echocardiogram) have been normal, and the GENT score which is made up of the number of features of Marfan syndrome which you display, is not high enough to warrant a diagnosis of Marfan syndrome.

It is most likely that you have a similar condition which is not life-threatening, like mild collagen deficiency. This is found more commonly in the population than Marfan syndrome. For every 10 patients who are referred to me as having possible Marfan syndrome, only one is actually diagnosed. The other nine have something which is similar.

Basically, you have only skeletal features, with long slim body build, slim arms and legs, long fingers and toes, mild pectus excavatum, and slightly flat feet. There is only one skeletal feature which is recognised as severe enough to count toward Marfan syndrome diagnosis, and that is spinal curvature severe enough to warrant surgical
correction. You do not have that.

Your tendency to anxiety and depression may also be a feature of the mild collagen deficiency. So perhaps those two features are related.

Please ask your GP to refer you to your regional genetics clinic, for further counselling regarding the possibility of having a connective tissue disorder. It may be that they will do a DNA test for Marfan syndrome simply to reassure you. It would be a bonus if they can classify your connective tissue disorder. Perhaps it is a mild Ehlers-Danlos syndrome – the common kind, and not at all dangerous. They will ask if you have any stretchy joints and do a joint score for you.

If you would like to take this email to your doctor and ask for a referral for counselling, that would be the best solution. You have experts close at hand. I hope this is reassuring for you.
 

 

Dr Child's Casebook: Appearances Can Be Deceptive – The Relative Anomaly
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