Application of a reliable and rapid polymerase chain reaction based method in the diagnosis of myotonic dystrophy type 1 (DM1) in India☆

DM1 is caused by CTG repeat expansion in the 3'-UTR of the DMPK gene. DM1 patients have expansions of greater than 50 repeats and up to many thousands. The intention of the present study is the establishment of reliable and rapid polymerase chain reaction methodology in early screening of DM1 patients and their family members. PCR followed by TP-PCR was assessed for screening of 27 cases (from 26 families) and 75 family members and 300 control samples. All patients had CTG repeat expansion while forty seven (63%) and twenty eight (37%), out of seventy five family members were heterozygous and homozygous respectively. Similarly, two hundred thirty (76.77%) and seventy (23.33%), out of three hundred control subjects were heterozygous and homozygous respectively and the number of repeats varied from 5 to 35. Thirteen complete family screenings were done. Thus, TP-PCR is a reliable and rapid molecular technique for the detection of CTG repeat expansion in DM1.