MILAN, Italy — Sales at Italy's Prada are growing at double-digit rates in Asia while any forecast for the American market is hard to make due to the health emergency, the Chief Executive of the luxury group Patrizio Bertelli said on Thursday."In (Asia and China), sales are growing at important — double digit — rates and we are confident that this trend can continue also in the months to come," Bertelli told online fashion magazine WWD in an interview, adding that consumers had returned to "fast and sustained" spending.In a separate interview, Bertelli's son Lorenzo, the 32-year-old head of marketing and communications of the fashion house, said he did not rule out replacing his parents at the head of the company in the future."I like to challenge myself and solve problems. I simply want to enjoy what I'm doing. I'm now enjoying what I'm doing. And so...why not?" he told The Business of Fashion, answering a question on the succession plans at Prada.By Claudia Cristoferi; editor: Giulia Segreti.