Theater: “Kimberly Akimbo,” new musical by David Lindsay-Abaire and Jeanine Tesori

High schoolers are obsessed with the important thing in life. Like getting a date. Finding a partner for their science project. Lining up costumes for their HS musical.

But what if your adolescent problems were somewhat more grave? Like having been born with a rare disease that makes you age 4.5 times faster, thus making you a sixtysomething high schooler? Such is the condition that afflicts young/old Kimberly (played by the marvelous Victoria Clark) in David Lindsay-Abaire’s new musical “Kimberly Akimbo.”

Sound like a drag? Au contraire. Every word of the book is witty, and every note of the score (by Jeanine Tesori who scored “Caroline or Change”) is catchy. Not to reveal too much more but after you hear a song called “My Disease” you’ll never look at scurvy the same way again.

Of course, there are plenty of other reasons to love KA. Starting with Kimberly’s BF Seth (played by Justin Cooley who’s the next Keegan-Michael Key). His jokey delivery of the haha lines lands every time. Then there are Kimberly’s wackadoodle parents (Allie Mauzey and Stephen Boyer, the comedian who made “Hand to God” so memorable.)

Speaking of memorable, I’ll warrant you’ll never forget Kimberly’s Aunt Debra, played by Bonnie Milligan. She’s an ex-con that’s cooked up a scheme for the teens to raise money for their school play’s costumes—and for her to abscond with her share of the dough to Hawaii. Bonnie’s Twitter handle is @beltingbonnie. Don’t need to say much more than that about this prodigious lady’s prodigious talent.

With ensemble playing that calls to mind “Little Miss Sunshine” and loopy humor similar to “Avenue Q,” KA is the best musical we’ve seen from Atlantic Theater Company since “The Band’s Visit.”  And unlike TBV which focused on Arab-Israeli relations, KA does focus on questions troubling every teen. Like dealing with your mean parents and getting your first kiss. What could be more important than that?