Alpha-1-antitrypsin Pi phenotyping was performed by thin-layer isoelectric focusing on samples from 1653 healthy white blood donors. The variants were confirmed by the acid-starch gel technique and crossed immunoelectrophoresis, with complete agreement between the two methods. The allele frequencies in this population were PiM, 0.9019; PiS, 0.0713;PiZ,0.0142; PiI, 0.0036; PiF, 0.0036; PiV, 0.0024. In addition, some rare phenotypes (MX, IS, LM) were noted. No difference was noted in the distribution of the variant alleles between males and females. The significance of the high frequency of the S allele is related to the ethnic origin of this population. The agreement of the results obtained by our technique and by acid-starch gel electrophoresis confirms the validity of Pi determination by thin-layer isoelectric focusing.

No abstract

Among 55 amyloidoses, the detection of a monoclonal protein (MP) led to the selection of 15 primary and 3 myeloma-associated types of amyloidosis. Therefore the presence of a MP gives evidence for an immunocytic amyloidosis. The lambda-light-chain nature of MP and the abundant production of free light-chains are two of the factors predisposing to the production of amyloid deposits (AL) in the course of immunocyte dyscrasias.

No abstract

Monoclonal gammopathies are found in patients with myeloma, lymphoid malignant disorders, and amyloidosis. They are also discovered in patients with other diseases, and even in healthy people over 70 years.' 2 In such cases monoclonal gammopathies are of undetermined significance, and therefore of little if any diagnostic value.