After years of seeing her granddaughter in jeans that were too long and too loose, Karen Bowersox searched hard for brands that would work for the girl and others with Down syndrome. None existed.

“There was nothing that fit them,” said Bowersox, of suburban Cleveland. Convinced that “people with disabilities are a forgotten population in the world,” Bowersox, an entrepreneur with “no clue” about the garment industry, spent four years creating Downs Designs pants, “shaped and sized” for children and adults with Down syndrome. All of the brand’s pull-on jeans, khakis and black slacks have an elastic waist, belt loops, shorter proportioned legs and a mock fly to simplify dressing. The Downs line is part of her larger NBZ Apparel International, which stands for No Buttons/Zipperless.

Mindy Scheier, on the other hand, was a career fashion designer facing an urgent plea for jeans from her son Oliver, then 8, whose muscular dystrophy required leg braces. Only sweatpants would fit over the hardware and still enable him to use the bathroom by himself.

So she sliced up boys denims from Target and sewed Velcro strips from the hem to just below the knee to accommodate his braces, and replaced the zipper with easier fasteners. Those desperation jeans marked the first time Oliver could put on pants that had a zipper or buttons and use the restroom on his own.

Today, a growing number of clothing and footwear companies offer style, dignity and independence to younger, hipper consumers with disabilities.

“Adaptive design” it’s called, regular clothing and shoes reengineered for children and adults with physical, cognitive or sensory issues.

Elastic, snaps, magnets, large buttons, zippers, drawstrings and Velcro fasten everything from dress shirts and raincoats to swim trunks and pajamas. Spine-length back zippers on jumpsuits deter stripping by people with dementia or autism.

Onesies have concealed openings for abdominal access. Dresses, shirts and hoodies have two angled front zippers for access to chest ports, catheters or PICC lines used for medicine infusions. Cozy fabrics, flat seams, tag-free labels and the lack of back pockets prevent sensory distress and skin injuries. Sneakers with zippers and fastener closings make shoes more manageable.

Longtime Canadian designer Izzy Camilleri — known for high-end, high-style furs, gowns and costumes worn by actors and rockers — made her first adaptive piece 15 years ago: a custom coat for Toronto Star journalist and disability activist Barbara Turnbull, who was paralyzed from the neck down at 18. (She died at 50 in 2015.)

“I’d never worked with someone in a wheelchair, with a disability. It was quite eye-opening and humbling,” Camilleri said by phone from her Toronto showroom. Turnbull’s capelike coat “needed to be shorter in the back, with pockets on the inside to keep her hands warm, and a long zipper pull in front that her service dog could operate. I just became much more compassionate, knowing what it takes (for people with disabilities) to get through their day.”

Her IZ Adaptive collection offers wardrobe basics mostly in black, white, gray and khaki for women and men. Camilleri, like other adaptive designers, often creates two collections: one for people able to stand, which is how conventional apparel patterns are configured, and the other for people who sit, most often in wheelchairs, which means clothes must fit a body folded at angles at the hips and knees. “Seated” clothes are cut wider across the lap and thighs, with a modified waist that avoids pressure on the abdomen while providing coverage and comfort in the rear. Coats and blazers are cut shorter in the back to avoid bunched fabric that can irritate skin and internal organs.

Tommy Adaptive, part of the Tommy Hilfiger brand, debuted in 2016, bringing the designer’s signature sporty-preppy look to young people with disabilities. Scheier recalled demonstrating Oliver’s made-in-the-kitchen jeans to Hilfiger executives while explaining the concept, and its importance, to them. Tommy Adaptive for adults followed in 2017.

Semantics aside, clothes that fit properly “increase confidence and independence,” said Alette Coble-Temple, a psychology professor at John F. Kennedy University in California and a disability rights activist.

Although she wears conventional garb, the 2016 Ms. Wheelchair America winner said friends with disabilities are thrilled that newer adaptives “look hip, and they can get into them without having to contort their body.”

For Carolyn Pioro, a circus aerialist who became a quadriplegic after a trapeze accident, her custom Izzy Camilleri coat “was a game changer.”

“No one has to lean me forward in my chair or raise my arms or do any sort of ‘Carolyn manipulation’ in order to get it on or off.”

Her trapeze accident may have, at times, “taken my dignity,” she said recently by phone, but it certainly “did not take my vanity.”