<unk>  (PS) are a group of rare genetic disorders that mimic physiological aging, making affected individuals appear to be older than they are. The term<unk> does not necessarily imply progeria (Hutchinson–Gilford progeria<unk> , which is a specific type of<unk><unk>  means "resembling premature aging," a definition that can apply to a broad range of diseases. Familial Alzheimer's disease and familial Parkinson's disease are two well-known accelerated-aging diseases that are more frequent in older individuals. They affect only one tissue and can be classified as unimodal<unk> . Segmental progeria, which is more frequently associated with the term<unk>  tends to affect multiple or all tissues while causing affected individuals to exhibit only some of the features associated with aging. All disorders within this group are thought to be monogenic, meaning they arise from mutations of a single gene. Most known PS are due to genetic mutations that lead to either defects in the DNA repair mechanism or defects in lamin A/C. Examples of PS include Werner<unk> (WS), Bloom<unk> (BS), Rothmund–Thomson<unk> (RTS), Cockayne<unk> (CS), xeroderma pigmentosum (XP), trichothiodystrophy (TTD), combined xeroderma pigmentosum-Cockayne<unk> (XP-CS), restrictive dermopathy (RD), and Hutchinson–Gilford progeria<unk> (HGPS). Individuals with these disorders tend to have a reduced lifespan.<unk>  have been widely studied in the fields of aging, regeneration, stem cells, and cancer. The most widely studied of the<unk>  are Werner<unk> and Hutchinson–Gilford progeria, as they are seen to most resemble natural aging.
Progeroid syndromes
Zechi-Ceide syndrome
Roemheld syndrome
Warkany syndrome
Rabbit syndrome
Bart syndrome
Nevo syndrome
Havana syndrome