Mumbai, April 29 -- COMEX copper renews downturn after edging up to a one-week high in the previous session as a stronger greenback weighs on the red metal. The dollar is staying upbeat ahead of US Q1 GDP report and April employment data this week to understand US economic outlook. Any unwarranted developments could add pressure on dollar and in turn support the commodity. Currently, the counter is quoting at $4.87 per pound, down 0.25% on the day. Besides, choppy trade on Wall Street also limited gains in the metal. The Nasdaq edged down 16.81 points or 0.1 percent to 17,366.13, the S&P 500 inched up 3.54 points or 0.1 percent to 5,528.75 and the Dow rose 114.09 points or 0.3 percent to 40,227.59. On the MCX, copper stayed above Rs 850 per...