The exact cause of alopecia areata is unknown, but it is believed to be an autoimmune disorder where the body's immune system mistakenly attacks hair follicles, leading to hair loss. 

Symptoms: 

• Hair loss in round patches (alopecia patches) 

• Hair may be thin, broken, or completely absent within the patches 

• Patches may be small or large 

• May have smooth, bald areas or exclamation point hairs (hairs that are thicker at the base and taper to a point) 

• May experience itching or burning in the affected areas 

Types: 

• Alopecia areata multifocal: Multiple small patches of hair loss

• Alopecia totalis: Complete loss of hair on the scalp

• Alopecia universalis: Loss of all body hair, including eyelashes and eyebrows