Medknow Publications on behalf of the Neurological Society of India
Abstract
Background : Duchenne muscular dystrophy (DMD) is the most common
muscular dystrophy that affects young boys and the dystrophin gene on
the X chromosome has been found to be associated with the disorder.
Materials and Methods : In this prospective study, 112 clinically
diagnosed DMD patients had muscle biopsy and were tested for exon
deletions. Genotyping was also carried out at STR44, STR45, STR49 and
STR 50 markers in 15 families. Results : Of the 112 clinically
suspected DMD patients, the diagnosis of DMD was confirmed by
histopathology and/or genetics in 101 patients. The mean age of onset
was 3.1±1.44 years (1-6 years) and the mean age at presentation
was 8.0±3.1 years (1.1-18.0 years). Delayed motor milestones were
present in 63 (62.3%) patients. The mean creatine kinase value was
11822.64±8206.90 U/L (1240-57,700). Eighty-four patients had
muscle biopsy and immunohistochemistry was done in 60 muscle samples,
all of which demonstrated absence of dystrophin staining. Of the 60
dystrophin-negative cases, 73% showed deletion of at least one exon.
Single exon deletion was found in 20.4%. Distal hotspot Exons 45, 47,
49 and 50 were the commonly deleted xenons and the deletion rates were
36%, 35%, 33.7% and 38.5% respectively. Conclusions : In this study
population in south India the deletion rate was 73% and were more
frequent in the distal end exon. With the availability of genetic
analysis, the first investigation of choice in DMD should be genetic
studies and muscle biopsy should be considered only if the genetic
tests are negative or not available