👤 Kazuhiro Sonomura

Lymphoplasmacytic lymphoma (LPL) is a type of low-grade B-cell lymphoma, with 90-95% of cases associated with Waldenström macroglobulinemia, characterized by the presence of IgM-type M-protein. We report, for the first time, a case of LPL-producing Bence Jones (BJ) protein kappa. The patient was a 78-year-old woman admitted to our department due to general fatigue and proteinuria that had persisted for 2 months. No M-protein was detected by blood immunofixation, but kappa-type BJ protein was detected in the urine. Light microscopy of a kidney biopsy sample revealed infiltration of lymphocytes and plasma cells into the perirenal adipose tissue and renal interstitium. The infiltrating cells exhibited kappa light chain restriction. Bone marrow examination revealed clusters of immature plasmacytoid lymphocytes that were CD20 positive, CD5 negative, and exhibited light chain restriction. Genetic analysis detected a MYD88 mutation, leading to the diagnosis of LPL in the patient. Six months after starting treatment with tirabrutinib, urinary protein levels improved to 0.2 g/gCr. Renal infiltration was identified due to urinary protein, and currently, no extramedullary lesions outside the kidneys are observed. Tirabrutinib has been extremely effective, but careful follow-up is still required. Show less

To assess the use of plasma free amino acids (PFAAs) as biomarkers for metabolic disorders, it is essential to identify genetic factors that influence PFAA concentrations. PFAA concentrations were absolutely quantified by liquid chromatography-mass spectrometry using plasma samples from 1338 Japanese individuals, and genome-wide quantitative trait locus (QTL) analysis was performed for the concentrations of 21 PFAAs. We next conducted a conditional QTL analysis using the concentration of each PFAA adjusted by the other 20 PFAAs as covariates to elucidate genetic determinants that influence PFAA concentrations. We identified eight genes that showed a significant association with PFAA concentrations, of which two, SLC7A2 and PKD1L2, were identified. SLC7A2 was associated with the plasma levels of arginine and ornithine, and PKD1L2 with the level of glycine. The significant associations of these two genes were revealed in the conditional QTL analysis, but a significant association between serine and the CPS1 gene disappeared when glycine was used as a covariate. We demonstrated that conditional QTL analysis is useful for determining the metabolic pathways predominantly used for PFAA metabolism. Our findings will help elucidate the physiological roles of genetic components that control the metabolism of amino acids. Show less