A THREE-YEAR-OLD boy with a life-threatening condition yesterday received a stem cell transplant from his baby sister’s umbilical cord blood at the Shanghai Children’s Medical Center.

In helping her brother, the one-month-old girl — known as Tongtong — became the youngest donor of umbilical cord blood in the city.

The little boy, An’an, suffers from aplastic anemia, which means that his bone marrow does not make enough new blood cells.