Langerhans cell histiocytosis with central nervous system involvement: follow-up by FDG-PET during treatment with cladribine

The prognosis of patients with Langerhans cell histiocytosis (LCH) involving the central nervous system (CNS) is generally poor, despite reports of clinical responses to chemotherapy, surgery, and radiation. We report on a patient with a 20-year history of relapsing multisystem LCH who developed progressive neuropsychiatric symptoms, including diplopia, ataxia, and mental deterioration. There was a regression of lesions in the brain stem and cerebellum following chemotherapy with cladribine (2-CdA) as evidenced by positron emission tomography (PET) scans. In conclusion, our experience is encouraging for the use of cladribine in CNS LCH. PET may be a useful modality for the monitoring of CNS disease activity in LCH and provides additional information in comparison with NMR imaging.     

The organization and rate of evolution of wheat genomes are correlated with recombination rates along chromosome arms

Genes detected by wheat expressed sequence tags (ESTs) were mapped into chromosome bins delineated by breakpoints of 159 overlapping deletions. These data were used to assess the organizational and evolutionary aspects of wheat genomes. Relative gene density and recombination rate increased with the relative distance of a bin from the centromere. Single-gene loci present once in the wheat genomes were found predominantly in the proximal, low-recombination regions, while multigene loci tended to be more frequent in distal, high-recombination regions. One-quarter of all gene motifs within wheat genomes were represented by two or more duplicated loci (paralogous sets). For 40 such sets, ancestral loci and loci derived from them by duplication were identified. Loci derived by duplication were most frequently located in distal, high-recombination chromosome regions whereas ancestral loci were most frequently located proximal to them. It is suggested that recombination has played a central role in the evolution of wheat genome structure and that gradients of recombination rates along chromosome arms promote more rapid rates of genome evolution in distal, high-recombination regions than in proximal, low-recombination regions.