WASHINGTON - The numbers of affected consumers are as yet impossible to predict, but mortgage-credit experts warn that the recent massive data breaches at Target, Neiman Marcus and other retailers could have significant side effects on some real-estate transactions in the coming months, as damaged credit files depress scores and jeopardize loan applications and home sales. The Target breach alone could touch as many as 70 million credit- and debit-card customers, according to the company. Neiman Marcus says data on 1.1 million of its customers may be vulnerable to fraud. So what are the potential blowbacks on home sales and mortgage applications? Start with the basics. Identity theft, if not corrected quickly, can make a mess of anyone's credit-bureau files. Though victims may not be liable for the unauthorized debts racked up, their credit reports - and in turn their credit scores - can be damaged for weeks or months. Listen to Terry Clemans, executive director of the National Consumer Reporting Association, the primary trade group that represents independent credit-reporting companies serving the mortgage industry.