When the San Francisco Gay Men’s Chorus performs “For a Look or a Touch” next week, it will be the Bay Area premiere of composer Jake Heggie’s Holocaust-themed choral opera.

Not the Nazi Holocaust perpetrated against Jews. The Nazi Holocaust perpetrated against gays and lesbians.

Commissioned in 2009 by the Seattle-based nonprofit Music of Remembrance, which brings to life musical works commemorating the Holocaust, “For a Look or a Touch” has already enjoyed performances across the United States and in Europe.

The chorus will perform the piece April 1 and 2 at Davies Symphony Hall in a concert called “Passion.” The concert includes the opera as well as world premieres of two other pieces, “My Friend, My Lover: Five Walt Whitman Songs” and “#twitterlieder: 15 Tweets in 3 Acts.” The Contemporary Jewish Museum is a co-sponsor of the performances.

For San Francisco resident Heggie, who also wrote the celebrated operas “Moby-Dick” and “Dead Man Walking,” this hometown performance is overdue. “It’s so heartwarming when your music can be appreciated at home,” said the composer.

Some hearts may be chilled by the tragic storyline of the opera, which is divided into seven sections and scored for baritone, men’s chorus and chamber orchestra. The music veers from frenetic Kurt Weil-esque flourishes to mordant motifs. Heggie’s frequent collaborator, Gene Scheer, wrote the libretto.

For the upcoming performances, actor Kip Niven portrays Gad Beck, an elderly German Jew remembering his lost love, Manfred Lewin (portrayed by baritone Morgan Smith), a Jew who died in Auschwitz.

The story is based on true stories of gay German men hounded, arrested, deported to concentration camps and murdered by the Nazis. The pink triangle was the insignia gays and lesbians were forced to wear, the gay concomitant to the infamous yellow star. When the San Francisco Gay Men’s Chorus takes the stage, they will wear black T-shirts adorned with the pink triangle.

Some historians estimate as many as 100,000 gays and lesbians were murdered in the Holocaust. But unlike the postwar outrage over the loss of 6 million European Jews, the persecution of gays and lesbians remained an unspoken historical footnote for years.

“I started looking for poetry, stories and memoirs,” recalled Heggie, 53, of his research, “and there wasn’t any because after the camps were closed it was still illegal [in Germany] to be gay. They were rearrested, went underground or fled. You didn’t talk about it.”

Some did speak out, among them Gad Beck, who miraculously rescued the prewar diary of his young lover. After Lewin died, Beck joined the underground, rescuing fellow Jews and helping some immigrate to Palestine. He died in Berlin in 2012, the last known gay Holocaust survivor.

The story of Gad and Manfred became the core of “For a Look or a Touch” — the title referring to the law that allowed German police to arrest gay men for as little as a look or a touch.

“You always have to go back to the human story,” Heggie said. “I can’t write a piece about the Holocaust. I wrote about people going through the Holocaust. That’s what makes it tragic.”

Chorus artistic director Tim Seelig saw the opera in Seattle and was so moved, he knew he would someday bring the piece to San Francisco. Yet he also knew the opera’s bold theatricality and brutal subject matter might challenge audiences. “The whole thing is a big risk,” Seelig said. “Our audience is accustomed to a big male chorus standing and singing.”

Seelig says a core mission of the chorus is “to educate and tell our stories. To be able to tell this enormous part of LGBT history is one of our greatest joys.” But he thinks people have short memories when it comes to the lessons of history.

Seelig recently attended a meeting of gay and lesbian choral directors, where one associate said a younger singer questioned why some continue to wear the red AIDS ribbon.

“They think it’s an icon of the past,” he said. “Those of us who were older, who lost so many, were shocked for a moment, but then you understand that’s where the young are coming from. As one of the senior citizens among the group, I said we can never forget. If we ever forget we will have lost. If young people don’t know why we wear a red AIDS ribbon, they certainly don’t know why we wear the pink triangle.”

Heggie, who is gay, admits that before he began work on the opera, he did not know much about the history of Nazi persecution of gays. But he remembers all too well the early days of the AIDS crisis when some fearmongers suggested HIV patients be quarantined in camps.

“The AIDS years felt like a different kind of Holocaust,” he said, “a different plague and persecution. I lost so many friends. Once again it was a way to stigmatize gay people.”

Seelig understands a shared sense of pain the Jewish and LGBT communities feel over the Holocaust. And he echoes the oft-repeated warning “Never again,” especially as anti-Semitism and homophobia rage on unabated.

“I have a feeling at the end of the Holocaust, the sentiment was ‘We’re good here,’ ” he said. “When AIDS stopped being in our face, when we stopped seeing men covered with sores and walking with canes, I know that society said we’re good here. But those still dealing with it, the millions around the world not in our face, know we’re not good here.”

S.F. Gay Men’s Chorus performs “Passion,” 8 p.m. April 1-2 at Davies Symphony Hall,  201 Van Ness Ave., S.F. $25-$90. (415) 392-4400 or www.sfgmc.org

Excerpts from “For a Look or a Touch” will be previewed 3 p.m. Sunday, March 29 at the Contemporary Jewish Museum, 736 Mission St., S.F. www.thecjm.org