Validation of sensitivity and specificity of tetraplet-primed PCR (TP-PCR) in the molecular diagnosis of myotonic dystrophy type 2 (DM2).
Myotonic dystrophy type 2 (DM2, OMIM #602688) is a multisystemic hereditary degenerative disease caused by a tetranucleotide CCTG expansion in the ZNF9 gene. Routine testing strategies for DM2 require the use of Southern blot or long-range PCR, but the presence of very large expansions and wide somatic mosaicism greatly reduce the sensitivity of these reference techniques. We therefore developed and validated a tetraplet-primed PCR (TP-PCR) method to detect the DM2 mutation by testing 87 DM2-positive and 76 DM2-negative previously characterized patients. The specificity of this technique was evaluated including DNA samples from 39 DM1-positive patients. We then attempted a prospective analysis of 50 patients with unknown genotype who referred to our center for diagnostic or presymptomatic tests. Results show that TP-PCR is a fast, reliable, and flexible technique, whose specificity and sensitivity is almost 100%, with no false positive or negative results either in retrospective and prospective applications. We therefore conclude that using this technique, in combination with the short-range PCR, is sufficient to correctly establish the presence or the absence of ZNF9 expanded alleles in the molecular diagnosis of DM2.
Catalli
Claudio
C
Department of Biopathology and Diagnosing Imaging, Tor Vergata University of Rome, Rome, Italy. claudio.catalli@gmail.com
Morgante
Alessandra
A
Iraci
Raniero
R
Rinaldi
Fabrizio
F
Botta
Annalisa
A
Novelli
Giuseppe
G
D017931:DNA Primers; D004587:Electrophoresis, Agar Gel; D006801:Humans; D025202:Molecular Diagnostic Techniques; D020967:Myotonic Disorders / Q000175:diagnosis / Q000235:genetics; D009223:Myotonic Dystrophy; D016133:Polymerase Chain Reaction / Q000379:methods*; D012680:Sensitivity and Specificity
D017931:DNA Primers