In 2002, Jenny and Jon Steingart founded the Off Broadway incubator Ars Nova as a way of honoring Jenny’s brother, Gabriel Wiener, who in 1997 died of a brain aneurysm at the age of 26. Now, as the nonprofit theater is marking its 20th anniversary, the couple is facing another wrenching struggle: Jon has A.L.S., the severe neurological disorder also known as Lou Gehrig’s disease. “Every painful experience in my life — if I have to live through it, I am going to come out on the other side with a lesson and a way to give back in some way,” Jenny Steingart said in a recent interview at their home on the Upper West Side. “Because a loss without some meaning behind it is really hard to live with.”So this anniversary, to be celebrated with a gala on Monday, also finds the Steingarts feeling great satisfaction, having created an institution that — in the wake of the 9/11 attacks — has played a crucial role in the professional development of so many artists. Among those who have worked at Ars Nova are Lin-Manuel Miranda, Thomas Kail, Christopher Jackson and Phillipa Soo of “Hamilton” fame; Bridget Everett, the actress and cabaret performer of the acclaimed HBO series “Somebody Somewhere”; and Dave Malloy, who created “Natasha, Pierre & the Great Comet of 1812” at Ars Nova.

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