The Seventh-day Adventist Church headquartered in Silver Spring, Maryland, United States, has released the following official statement:
A rumor circulating that Pope Francis has a brother who is a member of the Seventh-day Adventist Church is untrue. Please disregard a widely distributed YouTube sermon in which Hugo Gambetta makes these claims. Church leaders from South America, who are familiar with the situation, have confirmed that Gambetta is a former Seventh-day Adventist minister.
Source: Adventist News Network