GENETIC-HETEROGENEITY OF FAMILIAL PRIMARY CUTANEOUS AMYLOIDOSIS - LACK OF EVIDENCE FOR LINKAGE WITH THE CHROMOSOME-10 PERICENTROMERIC REGION IN CHINESE FAMILIES

Primary cutaneous amyloidosis is a relatively common skin disease in S outheast Asia, South America, and the Republic of China. Although most cases are sporadic, some patients have a family history, suggesting t hat genetic factors may play a role in its pathogenesis. Some patients with multiple endocrine neoplasia type 2A also have a clinical pictur e of primary cutaneous amyloidosis, It is thus suggested that the gene of familial primary cutaneous amyloidosis is linked to the pericentro meric region of chromosome 10, the location of the RET proto-oncogene. We have carried out-linkage analysis in seven families with cutaneous amyloidosis using four dinucleotide repeat markers from the RET regio n, Negative lod scores at all recombination frequencies were obtained. We thus conclude that there is no evidence for linkage between Chines e families with primary cutaneous amyloidosis and the pericentromeric region of chromosome 10, The distinct genetic basis, plus their appare nt phenotypic differences in sex ratio, age of onset, and sites of cut aneous lesions, suggests that familial primary cutaneous amyloidosis i ncludes clinical subtypes attributable to genetic heterogeneity.