To the Editor.—
Psoriasis in concordant, monozygotic twin pairs tends to be similar, with respect to age of onset, distribution pattern, severity, and course.1,2 The similarity in the behavior of the disease has been ascribed to the fact that both patients have two basic factors in common, ie, identical genetic endowment and nearly identical environmental conditions.1Recently we have observed 37-year-old monozygotic twins with a strikingly similar pattern of psoriasis on their hands (Figure) and feet. The patients, who have different jobs (one is a welder, the other is an ice-cream vendor), stated that their skin lesions first appeared in 1975 and—what is more—in the same month (October), while the welder was working abroad and the vendor was in Naples. In the following years, the disease ran a parallel course in the twins. The HLA typing yielded the identical haplotype for both, which is A1,2;B17,18;Cx,x;DR5,6y. Moderate diabetes and
Pisani M, Ruocco V. `Twin' Psoriasis in Monozygotic Twins. Arch Dermatol. 1984;120(11):1418–1419. doi:10.1001/archderm.1984.01650470024005
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