Robin Roberts is renowned for her kind heart and often uses her platform to help those in need.And on Friday, the Good Morning America star took to Instagram to ask her followers for their help.MORE: Inside GMA stars incredible homes - Amy Robach, Robin Roberts and moreThe TV host was marking the 14th birthday of a teenage boy called Joshua, who is in search for a donor to cure his sickle cell disease. VIDEO: GMA's Robin Roberts shares tour inside her colourful home to mark special occasionThe