cqvip:Background. Darier’s disease or keratosis follicularis is an autosomal domina nt acantholytic disorder that frequently arises as a result of spontaneous mutat ion. It is either a generalized or localized condition due to a mutation in the SERCA2 12q23q24,1 resulting in a faulty organization of the tonofilaments. We pr esent two siblings affected with the linear form of this disorder and discuss th ese cases as an example of the genetic mechanism of loss of heterozygosity. Case reports. A 7 year-old girl was referred for evaluation of linear lesions prese nt since the first year of age. Examination disclosed red, 1 to 2 mmpapulesthatc oalescedtoformlinearplaquesontheleftside of the vulvar and perianal areas, and o n the left hand and foot. Her older brother had similar lesions in a linear arra ngement on the left side of the face neck and homolateral foot. No lesions were found in their parents. Biopsies of both affected children revealed an intraepid ermal suprabasal cleft. Dyskeratotic cells were present in the spinous layer, an d corps ronds and grains near the granular layer. Discussion. The linear form of Darier’s disease could result from genetic mosaicism for this autosomal domina nt disorder. As these children have a more pronounced involvement than the usual Darier’s disease lesions, disposed in a linear arrangement, they probably repr esent a type 2 segmental manifestation of the disorder. Likewise, the presence o f the same linear disorder in two siblings could be explained by loss of heteroz ygosity for the Darier’s disease gene.
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