To clarify the relationships between marginal zone lymphomas (MZLs) and Waldenström macroglobulinemia/lymphoplasmacytic lymphomas (WM/LPLs), immunoglobulin heavy chain variable gene (IGHV) features were analyzed and the occurrence of MYD88 L265P mutations was identified in a series of 123 patients: 53 MZLs from the spleen (SMZLs), 11 from lymph nodes (NMZLs), 28 mucosa-associated lymphatic tissue (MALT) lymphomas and 31 WM/LPLs. SMZLs were characterized by overrepresentation of IGHV1-2 gene rearrangements with a canonical motif, without selection pressure and with long CDR3 segments. NMZLs had increased frequencies of IGHV3 genes. The IGHV gene was unmutated in most cases, often with long CDR3 segments. MALT lymphomas were usually associated with a mutated IGHV gene, but with the absence of selection pressure. WM/LPLs were associated with an IGHV3-23 overrepresentation and high IGHV mutation rate, with features of selection pressure and short CDR3 segments. MYD88 L265P mutations were almost restricted exclusively to WM/LPL patients. Taken all diagnoses together, all patients with MYD88 L265P mutations had an immunoglobulin M peak and almost all patients except one had bone marrow infiltration. These results demonstrate that the history of antigen exposure of the four entities studied was different and MYD88 L265P was specifically associated with WM/LPLs. WM/LPL may thus be functionally associated with constitutive nuclear factor-κB activation.

Mammalian pigmentation is controlled by the concerted action of Tyr, Tyrp1 and Dct producing eumelanin and/or pheomelanin in melanocytes. The ratio of these two pigments is determined by the agonist alpha-melanocyte stimulating hormone and the antagonist Agouti protein acting on the Mc1r. Here we show that the Agouti gene is over-expressed in Normande breed compared with Prim'Holstein breed. The Normande cattle have a characteristic coat color phenotype with a variable presence of black (eumelanin) hair over a red/brown background. We have found a previously undescribed full-length L1-BT element inserted in the 5'-genomic sequence of the Agouti gene in Normande cattle which promotes the over-expression of alternative transcripts. The variable expression of the alternative transcript directed by the long interspersed nuclear element promoter may be the origin of the brindle coat color pattern of the Normande breed. This new bovine Agouti allele isolated in Normande breed has been named Abr. Finally, as ectopic over-expression of Agouti in Ay mice is responsible for the obesity syndrome, we discuss the possible consequences of Abr for meat and milk production in cattle.

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