Familial occurrence of multiple myeloma and monoclonal gammopathy of undetermined significance in 5 siblings.

The etiology of monoclonal gammopathies remains unclear but familial occurrence of immunopathies seems to favor a possible hereditary background. In support of this view we report on a family in which five siblings had a monoclonal gammopathy. When MGUS was diagnosed in two of them, a family study was carried out: one sister died from multiple myeloma and four out of the seven living siblings were discovered to have a MGUS. The immunogenetic study (HLA) showed no direct correlation between haplotypes and the presence of the monoclonal protein. Nevertheless possible environmental exposure to viruses, chemicals and radiation was apparently excluded. This new report on familial involvement, the second ever reported for number of affected subjects, strongly supports the theory of genetic predisposition in the development of plasma cell dyscrasias.