Rock implied Pinkett Smith could be in G.I. Jane 2 – referring to the 1997 movie G.I. Jane, where Demi Moore shaves her head bald.

The Smith family, Jada Pinkett Smith and Willow, Will Smith, Jaden and Trey Smith at the 2022 Vanity Fair Oscar Party following the 94th annual Academy Awards ceremony. Photo: EPA-EFE

There is no cure for alopecia, and people with the condition may experience hair loss in large or small patches on their head and face, but it can also affect other parts of the body.

So what else do we know about the condition?

Alopecia is an autoimmune condition

Jada Pinkett Smith poses at the 2022 Vanity Fair Oscar Party following the huge drama during the 94th annual Academy Awards ceremony. Photo: EPA-EFE

For most people with alopecia, there are no other symptoms aside from their hair falling out in small patches. The patches are usually round, about the size of a coin.

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Some people experience hair loss that comes and goes throughout their life, while others have one episode that never returns, and the hair regrows fully.

Tyra Banks, who once walked the Victoria’s Secret runway, experienced alopecia areata as well. Photo: EPA

There are three main types of alopecia:

  • Patchy alopecia areata: This is the most common type of alopecia and involves hair loss in one or more coin-sized patches on the scalp or other body parts.

  • Alopecia totalis: This type involves the loss of all or nearly all hair on the scalp.

  • Alopecia universalis: A rarer type of alopecia, which leads to nearly all hair loss from the scalp, face and rest of the body.

The first sign of alopecia is usually the loss of circular patches of hair on the scalp. For men, however, it can be seen in the beard, and both men and women may notice loss of eyebrows or eyelashes.

Scream actress Neve Campbell also dealt with alopecia areata caused by stalkers, overworking and the stress she endured during her divorce. Photo: Paramount Pictures/Spyglass Media Group

For some people, the hair loss is preceded by a tingling, burning, or itching sensation.

Hair can regrow on its own, and outcomes are best for people who lost less hair initially, developed alopecia at a later age, have no family history of the condition, and have no changes in the pits and ridges of their nails, according to NIH.

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There is no cure for alopecia and the cause is unknown

Will Smith with young sons Jaden and Trey, and wife Jada Pinkett Smith in 2001. Photo: Reuters

While there is no cure for alopecia, there are treatments that encourage hair regrowth. The cause of the disease is unknown but scientists believe there is a genetic component, according to the NIH. It affects men and women equally, most commonly in the teens, twenties, or thirties.

Jada Pinkett Smith is open about her alopecia

Jada Pinkett Smith. Photo: @jadapinkettsmith/Instagram

Pinkett Smith has opened up about her alopecia before. In December, Pinkett Smith posted a video of herself on Instagram in which she showed off her shaved head and talked candidly about her hair loss.

Revealing a bald patch on the top of her head, Pinkett Smith said: “Y’all know I’ve been struggling with alopecia, and just all of a sudden one day, look at this line right here. It just showed up like that. Now this is going to be a little more difficult for me to hide, so I thought I’d just share it so y’all not asking any questions.”

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Pinkett Smith opened up about her alopecia on an episode of her Facebook series Red Table Talk in 2018.

“It was terrifying when it first started,” she said on the episode. “I was in the shower one day and then just handfuls of hair just in my hands.”

This article originally appeared on Insider