BOSTON — A mother's tweets sharing her son's hospital bill have gone viral as Senate Republicans are working to pass a new health care bill.Alison Chandra's son suffers from heterotaxy syndrome — a rare genetic disorder that causes organs to form incorrectly or in the wrong place.Chandra tweeted out a photo of a bill for her son Ethan's recent open heart surgery at Boston Children's Hospital Friday, saying without insurance her family would be paying more than $231,000.With insurance, the family owed $500.