Similarities and Differences Between WS and Aging

Werner's Syndrome is an inherited disease with clinical symptoms (forming a syndrome) that resemble premature aging (87). Early susceptibility to a number of major age-related diseases is a key feature of this disorder. Principal WS features include shortness of stature; senile appearance; cataracts and graying of the hair beginning at 20 to 30 years; skin changes (i.e., tautness, atrophy or thickening, ulceration) designated as scleroderma; joint deformities, soft-tissue calcifications and osteoporosis; atrophy of muscles and connective tissue; early cessation of menstruation; and increased incidence of neoplasms. Most of these conditions occur in aging as well but at a later age and with more or less severity (85).

The gene responsible for WS (known as WRN) is located on the short arm of chromosome 8. The predicted protein (1432 amino acids in length) shows significant similarities to DNA helicases (the enzymes capable of unwinding the DNA double helix). Four mutations in WS patients have been identified, one of the four was found in the homozygous state in 60% of Japanese WS patients examined. The identification of a mutated putative helicase as the gene product of the WS gene suggests that defective DNA metabolism is involved in the precociously aging WS patients (25).

Among some of the major differences between WS and aging is the type of inheritance—universal, multifactorial in aging, and autosomal-recessive in Werner's. Further, there is a high incidence of hypertension in aging but not in WS; the presence of dementia and other degenerative disorders of the central nervous system occur in aging but not in WS. The occurrence of soft-tissue calcifications is uncommon in aging but common in WS.

These differences are sufficient to justify the statement that WS is not merely a process of premature or accelerated aging. Rather, WS may be viewed as a "caricature" of aging. Both WS and aging may represent the result of generalized metabolic processes or aberrations thereof. Indeed, the overlap between the two entities is not surprising inasmuch as the various tissues of the human organism have only a limited repertoire of reactions to genetic abnormalities and environmental insults. Irrespective of similarities or differences, a study of the features of WS and aging will conceivably be useful in achieving an understanding of both.

The etiology of WS remains obscure, but among the several causes proposed, neuroendocrinologic dysfunction is supported by the occurrence of stunted growth, failure of gonadal maturation, and diabetes, either singly or in combination. However, the phenotypes observed in the affected individuals may result from mechanisms related to aging processes. If this is so, it could be inferred that cell autonomous functions dictate the pace of aging, at least in some organs and tissues. Further investigations of the WRN protein may reveal why particular systems and organs are differentially affected with aging (87).

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