Multiple self-healing squamous epithelioma in different ethnic groups: more than a founder mutation disorder?

Multiple self-healing squamous epithelioma (MSSE), also known as Ferguson-Smith Disease, is a rare cancer-associated genodermatosis with an autosomal dominant inheritance. Affected patients suffer from recurrent skin lesions, which clinically and histologically resemble keratoacanthomas or well-differentiated squamous cell carcinomas, but which, if left, undergo spontaneous regression, leaving pronounced scarring. The majority of MSSE cases previously described were of Scottish ancestry and all shared the same at-risk haplotype, suggesting that this disorder was caused by a founder mutation. The candidate locus for MSSE lies in a region of <4 cM in chromosome 9q22, between the markers D9S197 and D9S1809. We recently investigated MSSE families of non-Scottish origin. For every patient of these families, we obtained a detailed clinical history, with particular attention to the age of onset, distribution, and clinical course of their skin lesions. Once confirmed that they were really affected by MSSE, we performed haplotype analysis on them and their families. The haplotypes for polymorphic markers segregating with MSSE in non-Scottish and Scottish families differ, suggesting that MSSE is not caused by a founder mutation and might be more common than originally thought.