Affiliations: Division of Medical Genetics & Molecular Medicine
and Academic Center for Medical Genetics, Department of Medicine, Faculty of
Medicine Ramathibodi Hospital, Mahidol University, Bangkok, Thailand
Note: [] Corresponding author: Dr. Jakris Eu-ahsunthornwattana, Division
of Medical Genetics & Molecular Medicine, Department of Medicine,
Ramathibodi Hospital, Rama VI Rd., Phaya Thai, Bangkok 10300, Thailand. Office
Tel./Fax: +66 2 201 1374; Home Tel.: +66 87 912 7847; E-mail:
[email protected]
Abstract: Background: Duchenne muscular dystrophy (DMD), a lethal X-linked
disease affecting 1 in 3500 male births, and its more benign variant, Becker
muscular dystrophy (BMD), are caused by mutations in the dystrophin gene.
Because of its large size, analysing the whole gene is impractical. Methods
have been developed to detect the commonest mutations i.e. the deletions of the
exons. Although these tests are highly specific, their sensitivity is
inherently limited by the prevalence of deletions, which differs among
different populations. Methods: We reviewed our database for the detection of
Dystrophin gene mutation by means of 31-exon multiplex PCR in Thai males,
diagnosed clinically and biochemically with DMD or BMD from July 1994 to
November 2006. One index patient was chosen from each family for statistical
analysis. The overall sensitivity of the test, the number of fragment deleted,
and the deletion frequency of each fragment were calculated, along with their
95% confidence intervals (C.I.). Results: We found deletions in 99 out of the 202 index
patients (49%; Bayesian 95% C.I. = 42%–56%). 51% of these had
deletion in only one of the 31 exons tested, while the patient with the most
extensive deletions had 14 exons deleted. The mean number of deleted exons were
2.84 (BC_{a} bootstrap 95% C.I. = 2.37–3.48), or 5.02 (3.81–6.85)
if all the untested exons adjacent to the confirmed deleted exons were assumed
to be deleted. The region spanning exons 44-52 was the most frequently deleted.
These were similar to those reported in the Japanese. Conclusion: The multiplex PCR detected deletions only in about
half of the Thai patients. The diseases therefore should not be excluded solely
on the negative result if DMD/BMD is strongly suspected.
