UK shares little changed, GSK gains

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* FTSE 100, FTSE 250 about flat

* Trade tensions linger

* Brexit uncertainty also curbs risk sentiment

Sept 30 (Reuters) - UK shares were steady on Monday as investors largely opted for a wait-and-watch approach amid simmering U.S.-China trade tensions and Brexit worries, and a lack of significant corporate news.

The exporter-heavy FTSE 100 index was roughly flat, though GlaxoSmithKline added 2% after its maintenance therapy for a form of ovarian cancer reduced the risk of disease progression or death by 38% in a late-stage study.

The mid-cap FTSE 250 was also flat by 0709 GMT. (Reporting by Shashwat Awasthi in Bengaluru; Editing by Bernard Orr)