Demonstration of a mechanism of aneuploidy in human oocytes using Multifluor fluorescence in situ hybridization

Abstract

Objective: To evaluate the potential of Multifluor fluorescence in situ hybridization (M-FISH) for karyotyping the human oocyte and first polar body.

Design: Prospective case study.

Setting: Research laboratories, university hospital.

Patient(s): A 33-year-old woman with polycystic ovary syndrome who was undergoing ovarian stimulation and ICSI.

Main outcome measure(s): Karyotyping of all chromosomes within an oocyte and first polar body, using GV stage oocytes matured to metaphase II in vitro.

Result(s): Oocyte hyperploidy was diagnosed by M-FISH to be 23, X +15 cht +19 cht +22 cht. The correspond- ing polar body was hypoploid, with a karyotype of 23, X -15 cht -19 cht -22 cht. This was due to unbalanced predivision at meiosis I. Reprobing confirmed karyotype assignments for chromosomes X, 13, 18, and 21.

Conclusion(s): The mechanism involved in maternally derived aneuploidy can be defined by using M-FISH to simultaneously karyotype both oocyte and first polar body chromosomes at metaphase II. Multifluor FISH may be useful for investigative studies of maternally derived aneuploidy, which is a major cause of preimplantation waste in natural and assisted reproduction.