1997
Year 17
Prof. Robert C. Griggs
Chairman
University of Rochester School of Medicine, USA
THEME: GENE THERAPY : MYTH OR REALITY?
Genetic mechanisms are most complicated and variable and what is thought to be a single gene disorder may
show deficit in several genes as in limb girdle muscular dystrophy, of which there are eight recognised isoforms
today. Lesions of a single gene can cause different diseases depending on the gene lesion and its tissue expression
as in Duchenne muscular dystrophy (DMD) and its allelic form, Becker dystrophy, which occurs at the same gene
locus. The abnormality of a gene as in a mitochondrial gene can produce deafness in one patient, diabetes in a
second and stroke syndrome in a third. This emphasises the varied aspects of genotypic and phenotypic
heterogeneity. In DMD, an X-linked disorder, where the male of the family is affected, while the female is the
carrier. reverse genetic techniques were used to map the DMD gene locus. This, incidentally, has the distinction of
being the first-ever disease gene to be mapped. As a result of further studies, the protein expressed by the DMD
gene was identified shortly after this. This enabled gene replacement therapy to be attempted in DMD. However,
attempts at normal myoblast transfer into DMD patients by several researchers did not prove beneficial and these
trials have been suspended till the time newer approaches are arrived at.
