EVALUATION OF MULTIPLEX LIGATION DEPENDENT PROBE AMPLIFICATION AS A TOOL FOR DIAGNOSIS AND CARRIER DETECTION IN FAMILIES WITH A DYSTROPHINOPATHY.

We set out to evaluate multiplex ligation dependent probe amplification (MLPA) as a tool for diagnosis and carrier detection in families with a dystrophinopathy. Fifty three Indian families with provisional diagnosis of Duchene muscular dystrophy or Becker muscular dystrophy were evaluated by MLPA and multiplex polymerase chain reaction (PCR). Sanger sequencing was used to analyze the entire gene in one patient. Mothers were tested for carrier status whenever possible. Molecular analysis of DMD gene by combining MLPA and multiplex PCR yielded a mutation detection rate of 62% (33/53). Deletions were detected in 27/53 (51%) cases, duplications in 5/53 (9%) cases, a small deletion one case and Sanger sequencing detected a nonsense mutation in one case. Mutation was not detected in 36% (19/53) cases. Fifty six percent of mothers (9/16) were found to be carriers. MLPA helped to refine the results of multiplex PCR testing in 22 patients (5 duplications, 16 deletions and one small deletion). We also describe a situation where a deletion of single exon on MLPA (but not detected by multiplex PCR) was actually due to a deletion of two nucleotides in the probe ligation site. MLPA appears to score over multiplex PCR in diagnosis and carrier detection, specifically by detecting deletions and duplications that are not detected by traditional multiplex PCR.