CATARACT AND MYOTONIC-DYSTROPHY - THE ROLE OF MOLECULAR DIAGNOSIS

Myotonic dystrophy (dystrophia myotonica), the commonest and most vari able of the muscular dystrophies of adult life, has long been known to be associated with cataract, while slit-lamp examination- for specifi c lens opacities has been one of the principal methods of presymptomat ic detection of gene carriers. The recent discovery that the myotonic dystrophy mutation is an unstable DNA sequence, composed of varying nu mbers of CTG triplet repeats, now allows a specific molecular test for this disorder, as well as explaining the phenomenon of anticipation. A series of case reports is presented to illustrate the important prac tical applications of this development in relation to ophthalmic aspec ts of the disorder. Reassessment of the specificity of the ophthalmic changes may be required and it will be important for molecular analysi s to be used alongside ophthalmic studies, when determining whether fa mily members carry the mutation for myotonic dystrophy.