cutoff: a designated limit beyond which something cannot function or must be terminated
entity: that which is perceived or known or inferred to have its own distinct existence (living or nonliving)
xeroderma pigmentosum: a rare genetic condition characterized by an eruption of exposed skin occurring in childhood and photosensitivity with severe sunburn; inherited as a recessive autosomal trait in which DNA repair processes are defective so they are more likely to chromosome breaks and cancers when exposed to ultraviolet light