Nonsense mutation of EMX2 is potential causative for uterus didelphysis: first molecular explanation for isolated incomplete müllerian fusion

Abstract

Objective: To investigate the association between human empty spiracles homeobox 2 gene (EMX2) and incomplete müllerian fusion (IMF).

Design: Case-control study.

Setting: University-based hospital.

Patient(s): Cohort of 517 clinically well-characterized IMF cases and 563 control women.

Intervention(s): None.

Main outcome measure(s): In cases and control women, direct sequencing of EMX2 exons and further functional studies; for functional studies, wild-type and mutant EMX2 expression plasmids constructed; human embryonic kidney cells (HEK293FT) transfected with empty vector, wild-type EMX2, mutant EMX2, and 1:1 combination (wild-type/mutant plasmids) with additional functional studies performed to clarify the deleterious effect of the novel mutation detected.

Result(s): A novel nonsense mutation p.E142X was detected in one woman with a didelphic uterus (1 of 517, 0.19%). The results of Western blot analysis confirmed that the mutation caused a truncated protein as predicted, and functional studies proved that it resulted in a dominant negative effect.

Conclusion(s): The novel nonsense mutation we detected-EMX2, p.E142X- resulted in a dominant negative effect. The functional data were exemplified in HEK293FT cells. This reinforced the likelihood that EMX2 contributed to the pathophysiology of IMF. Although it is uncommon (0.19%), EMX2 is the first gene identified that if perturbed may cause isolated IMF.

Keywords: Dominant negative effect; EMX2; P63; incomplete müllerian fusion; müllerian duct anomalies.