Claire Bennet is able to regenerate her amputated toe with her Spontaneous Regeneration.

Spontaneous Regeneration is the ability to regenerate at a super human speed. In addition to the basic stem-cell division and differentiation present in all human beings, the DNA Alternate with this ability is capable of dedifferentiation. Normal specialized cells may revert to stem cells in the event of physical damage, and these stem cells can then attach to the damaged area and go through the basic stem-cell division and differentiation. Through this process, the Alternate can heal rapidly, and even regenerate damaged organs and lost limbs.

This ability is involuntary, and exhibits properties unique even to Alternates with biological mutations. The Alternate regenerates in seconds what humans may take months or years to fully regenerate. This regeneration appears to flawlessly replicate the damaged organ or missing limb, while human repairs are often imperfect.

Trauma to the brain stem can terminate all functionality and halt all regeneration, and is believed to be the only reliable method of 'dying' for the Alternate. Their regeneration leads to cellular rejuvenation, a form of biological immortality for the Alternate. Their cells that degrade are rapidly regenerated, meaning that once they complete puberty, they will not age.

Another phenomenon associated with this regeneration is its effect on humans. The blood of a regenerating Alternate is accepted by any blood type because it possesses the properties of both positive and negative O blood type. The blood is can be transfused to any blood type, and it can cause spontaneous regeneration in the recipient for a short duration after the transfusion. While the healing is permanent, after a short time, the recipient will lose the ability to spontaneously regenerate.