Bistreich’s suit alleges that both Gentile — a Democrat who represents Bath Beach, Bay Ridge, Bensonhurst and Dyker Heights — and his chief of staff John Mancuso targeted him because of his diagnosis and tormented him with pranks so distressing he was forced to quit his job in June 2016.

Mancuso once organized a mass-decapitation of the stuffed animals Bistreich kept on his desk.

Bistreich found his Teddy bears with their heads ripped off — with one mounted on a flagpole — and a stuffed toy dog had been gutted and painted red to seem bloody.

The suit also claims the bullying was tolerated and encouraged by Gentile, who laughed and clapped his hands when a staff member compared Bistreich to Avonte Oquendo — the autistic boy who died after escaping his school through an unattended exit — by suggesting Bistreich “test the doors.”