Characterization of monoclonal gammopathy in patients with amyotrophic lateral sclerosis.

BACKGROUND

Recently, new guidelines for the monitoring and the risk evaluation of monoclonal gammopathy with undetermined significance (MGUS) became available and the light chain MGUS subtype was defined.

AIMS OF THE STUDY: To characterize the type, risk and diagnostic implications of MGUS in patients with amyotrophic lateral sclerosis.

METHODS

We screened 97 consecutive patients with ALS and 97 age- and gender-matched controls for MGUS by serum electrophoresis and immunofixation and compared the characteristics of MGUS with population-based data.

RESULTS

MGUS was identified in 8.2% of ALS patients and 6.2% of controls (mean age: 62.5 years both). Seven of eight ALS patients with MGUS had 'low-risk MGUS'. M-protein was moderately increased in one ALS patient. The immunoglobulin distribution in ALS patients with MGUS was IgG kappa (n = 2), IgM lambda (n = 1) and light chains of lambda type (n = 3). No differences in demographic and clinical parameters were found between patients with and without MGUS.

CONCLUSIONS

The percentage of patients with MGUS is increased in ALS, but the immunoglobulin distribution is similar to that reported in the general population. MGUS in ALS mostly represents 'low-risk MGUS'; therefore, unnecessary diagnostic procedures should be avoided in ALS patients.