Posters

Abstract

SHOX is a member of the homeobox-containing gene family and is highly conserved amongst species as diverse as fish, chicken and humans. SHOX was first cloned in 1997 and shown to be causative for idiopathic short stature. It is located in the pseudoautosomal region (PAR1) and haploinsufficiency of SHOX has been implicated in short stature and additional skeletal malformations frequently observed in Turner syndrome. SHOX mutations have also been shown to underlie other phenotypes such as Leri-Weill and Langer syndrome. We have performed an in situ hybridisation analysis of SHOX expression during limb development in chicken embryos. We find that SHOX is expressed in a central region of the early limb bud, leaving a rim of non-expressing cells around it. When these buds are sectioned expression is found to be in a thin layer of mesenchyme just under the ectoderm. In later stages, expression is restricted to the proximal two thirds of the limb bud and eventually becomes expressed in the digital rays with stronger expression dorsally. We have started to explore how SHOX expression is controlled. When the apical ridge of a chick limb bud was removed, SHOX expression extended to the distal edge of the bud. We are currently testing whether Fgfs play a role in inhibiting SHOX expression in distal mesenchyme.