Familial myeloma, a new observation in two distinct pairs of siblings

Two families in which myeloma arose in sibling pairs are reported. In the first family the brother had an IgG multiple myeloma and died of respiratory failure due to bronchopneumonitis, whereas his sister is affected by an IgGλ multiple myeloma and is still well, 15 months after diagnosis. In the second family the brother had an IgGλ diffuse myeloma and his sister showed an IgGk multiple myeloma as evolution of a solitary myeloma of the L1 vertebral body; both siblings died of renal failure. No common environmental or genetic factors have been found in either family. An identical immunoglobulin idiotype was sought in the second family but the result was negative. Patients occupations, that were somehow similar in the first pair, have all been reported to be at increased risk for myeloma. The study of these patients, as well as a review of the other 37 myeloma families reported in the literature, neither produces firm evidence for a genetic or environmental pathogenesis nor is able to exclude a merely casual association.