Rapid responses are electronic letters to the editor. They enable our users to debate issues raised in articles published on thebmj.com. Although a selection of rapid responses will be included online and in print as readers' letters, their first appearance online means that they are published articles. If you need the url (web address) of an individual response, perhaps for citation purposes, simply click on the response headline and copy the url from the browser window. Letters are indexed in PubMed.
Eccles et al note that joint hypermobility is commonly associated
with psychiatric, anxiety and psychosomatic presentations.(1)
For at least one psychiatric disorder with joint hypermobilty, there
is a known genetic cause. Both joint hypermobility and anxiety are
clinical features of Fragile X syndrome which is a result of expansions of
CGG repeats at the 5' untranslated region of the FMR1 gene which is
located at q27.3 on the X chromosome. The expansion silences transcription
of the protein FMRP, a protein which normally regulates protein synthesis
at neuronal dendrites. This loss of regulation is an explanation for the
finding of abnormally long and immature dendritic spines in the brains of
people with Fragile X syndrome and of the consequent phenotypic
presentations of impaired learning and memory (2), and as prompted by
Eccles et al, by anxiety.
It may transpire that Fragile X syndrome is the prototype joint
hypermobilty brain- body interaction disorder, and joint hypermobilty may
also be a sub-phenotype of Fragile X syndrome.
1. Eccles J, Harrison N, Critchley H. Joint hypermobilty: psychiatric
manifestations. BMJ 2011: 398-399.
2. Garber K, Visootsak J, Warren T. Fragile X syndrome. European
Journal of Human Genetics 2008; 16: 666-672.
No competing interests
26 February 2011
CT3 in Psychiatry.
Ryburn Centre, Fieldhead Hospital, Ouchthorpe Lane, Wakefield WF1 3SP.