Portelance was born in Rigaud, Quebec, Canada, on 21 March 1909, to parents Henri Portelance (1885–1929) and Clementine Rozon (1884–1976). She had ten siblings: Marie-Rose (1907–2009), Nelson (1908–1980), MarieJeanne (1911–2000), Suzanne (1912–2001), Lucia-Beatrix (1913–2001), Raymond (1914–1981), Therese (1916–2006), Roland (1918–2007), Victor (1922–1922), and Albertine-Victorine (1922–2015).
Portelance never married, nor had children. Her older sister, Marie-Rose, died in November 2009, aged 102.
Portelance passed away in Rigaud, Quebec, Canada, on 5 March 2021, at the age of 111 years, 349 days.
At the time of death, she was the fourth-oldest known living person in Canada, behind Phyllis Ridgway, Cecile Klein, and Reita Fennell. Furthermore, she was the second-oldest living person in Quebec, behind Klein.
Her age was validated by LongeviQuest on 30 September 2023.
* “Marie-Blanche Portelance” – VIVA média
* Généalogie Henri Portelance – Généalogie du Québec et d’Amérique française