Single-Tube Dodecaplex PCR Panel of Polymorphic Microsatellite Markers Closely Linked to the DMPK CTG Repeat for Preimplantation Genetic Diagnosis of Myotonic Dystrophy Type 1

Abstract

Background: Preimplantation genetic diagnosis (PGD) of myotonic dystrophy type 1 (DM1) currently uses conventional PCR to detect nonexpanded dystrophia myotonica protein kinase (DMPK) alleles or triplet-primed PCR to detect the CTG-expanded alleles, coupled with analysis of linked microsatellite markers to increase diagnostic accuracy. We aimed to simplify the process of identification and selection of informative linked markers for application to DM1 PGD. Methods: An in silico search was performed to identify all markers within 1-1.5 Mb flanking the DMPK gene. Five previously known (D19S559, APOC2, D19S543, D19S112, and BV209569) and 7 novel (DM45050, DM45178, DM45209, DM45958, DM46513, DM46892, and DM47004.1) markers with potentially high heterozygosity values and polymorphism information content were selected and optimized in a single-tube multiplex PCR panel. Results: Analysis of 184 DNA samples of Chinese and Caucasian individuals (91 from unrelated, anonymized cord blood of Chinese babies born at the National University Hospital, Singapore, and 93 Caucasian DNA samples from the Human Variation Panel HD100CAU) confirmed the high polymorphism indices of all markers (polymorphism information content >0.5), with observed heterozygosity values ranging from 0.62-0.93. All individuals were heterozygous for at least 6 markers, with 99.5% of individuals heterozygous for at least 2 markers on either side of the DMPKCTGrepeat. The dodecaplex marker assay was successfully validated on 42 single cells and 12 whole genome amplified single cells. Conclusions: The DM1 multiplex PCR panel is suitable for use in DM1 PGD either as a standalone linkagebased assay or as a complement to DMPK CTG repeat expansion-mutation detection.