Expression of the myotonin protein kinase gene in preimplantation human embryos.

We have examined the expression of the myotonin protein kinase gene (MPK) in individual human preimplantation embryos. An allele-specific, reverse transcriptase polymerase chain reaction assay was developed to the required sensitivity using human buccal cells. Human cleavage stage embryos, derived by in vitro fertilisation, were assayed for MPK transcription directly, or after biopsy of a single blastomere used to determine the genotype of the embryo. The maternal and paternal genotypes were determined from cumulus cells and sperm, respectively. MPK gene transcripts were detected in embryos at the 1-cell--4-cell stage of development. Detection of transcripts from the paternally-inherited allele confirmed onset of embryonic MPK gene expression at this very early preimplantation stage.