Dean NL, Tan SL, Ao A. Instability in the transmission of the myotonic dystrophy CTG repeat in human oocytes and preimplantation embryos.
Fertil Steril 2006;
86:98-105. [PMID:
16716318 DOI:
10.1016/j.fertnstert.2005.12.025]
[Citation(s) in RCA: 22] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/31/2005] [Revised: 12/05/2005] [Accepted: 12/05/2005] [Indexed: 01/26/2023]
Abstract
OBJECTIVE
To elucidate the timing and variability of CTG repeat expansion within the human dystrophia myotonica protein kinase (DMPK) gene in early development.
DESIGN
Triplet-primed polymerase chain reaction was used to amplify the expanded CTG repeat in oocytes and embryos obtained from myotonic dystrophy 1 (DM1) patients, and a heminested polymerase chain reaction approach was used to amplify the normal CTG repeats in supernumerary IVF embryos.
SETTING
University hospital laboratory.
PATIENT(S)
Two DM1-affected females undergoing preimplantation genetic diagnosis who carried different CTG repeats. Also, 61 IVF patients who carried a (CTG)(5-18) and (CTG)(19-37) normal DMPK repeat.
INTERVENTION(S)
None.
MAIN OUTCOME MEASURE(S)
The degree of expansion of the repeat in the oocytes and embryos compared with the DM1-affected maternal repeat and the size of the (CTG)(19-37) repeat compared with the parental size in IVF embryos.
RESULT(S)
The degree of repeat expansion was greater than the DM1 maternal lymphocyte for two of four oocytes, including a germinal vesicle-stage oocyte and 17 of 20 three-cell to blastocyst stage embryos. A change in the (CTG)(19-37) repeat was seen in 7 (7%) of 95 paternal transmissions but in no maternal transmissions.
CONCLUSION(S)
Because the repeat was already expanded in the immature oocyte, the initial expansion most likely occurs during oogenesis. A variable degree of DMPK(CTG)(n) expansion in the embryo is seen from different mothers. In addition, instability in paternal transmission of normal-range (CTG)(19-37) repeats occurs at the level of the embryo.
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