Jonathan Sarna, a leading scholar of American Jewish history, is in critical condition at Yale New Haven Hospital.

Sarna, the Joseph H. & Belle R. Braun professor of American Jewish history at Brandeis University, and a JTA board member, fell ill while attending his daughter’s graduation at Yale University, the Forward reported.

Sarna, 59, also serves as chief historian of the National Museum of American Jewish History in Philadelphia and is a past winner of the National Jewish Book Award.

He has written, edited or co-edited more than 30 books, most recently “When General Grant Expelled the Jews” (Schocken, 2012), a National Jewish Book Award finalist.

JTA was unable to independently confirm details of Sarna’s illness. His colleague, Sylvia Barack Fishman, told the Forward the family has requested well-wishers to reach out by mail rather than making phone calls or sending email messages.