Sequence comparison of humans and chimpanzees is of interest to understand the mechanisms behind primate evolution. Here we present an independent analysis of human chromosome 21 and the high-quality BAC clone sequences of the homologous chimpanzee chromosome 22. In contrast to previous studies, we have used global alignment methods and Ensembl predictions of protein coding genes (n = 224) for the analysis. Divergence due to insertions and deletions (indels) along with substitutions was examined separately for different genomic features (coding, noncoding genic, and intergenic sequence). The major part of the genomic divergence could be attributed to indels (5.07%), while the nucleotide divergence was estimated as 1.52%. Thus the total divergence was estimated as 6.58%. When excluding repeats and low-complexity DNA the total divergence decreased to 2.37%. The chromosomal distribution of nucleotide substitutions and indel events was significantly correlated. To further examine the role of indels in primate evolution we focused on coding sequences. Indels were found within the coding sequence of 13% of the genes and approximately half of the indels have not been reported previously. In 5% of the chimpanzee genes, indels or substitutions caused premature stop codons that rendered the affected transcripts nonfunctional. Taken together, our findings demonstrate that indels comprise the majority of the genomic divergence. Furthermore, indels occur frequently in coding sequences. Our results thereby support the hypothesis that indels may have a key role in primate evolution.

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The online version of this article has a Supplementary Appendix. BackgroundThe expression levels of LPL, ZAP70, TCL1A, CLLU1 and MCL1 have recently been proposed as prognostic factors in chronic lymphocytic leukemia. However, few studies have systematically compared these different RNA-based markers. Design and MethodsUsing real-time quantitative PCR, we measured the mRNA expression levels of these genes in unsorted samples from 252 newly diagnosed chronic lymphocytic leukemia patients and correlated our data with established prognostic markers (for example Binet stage, CD38, IGHV gene mutational status and genomic aberrations) and clinical outcome. ResultsHigh expression levels of all RNA-based markers, except MCL1, predicted shorter overall survival and time to treatment, with LPL being the most significant. In multivariate analysis including the RNA-based markers, LPL expression was the only independent prognostic marker for overall survival and time to treatment. When studying LPL expression and the established markers, LPL expression retained its independent prognostic strength for overall survival. All of the RNA-based markers, albeit with varying ability, added prognostic information to established markers, with LPL expression giving the most significant results. Notably, high LPL expression predicted a worse outcome in good-prognosis subgroups, such as patients with mutated IGHV genes, Binet stage A, CD38 negativity or favorable cytogenetics. In particular, the combination of LPL expression and CD38 could further stratify Binet stage A patients. ConclusionsLPL expression is the strongest RNA-based prognostic marker in chronic lymphocytic leukemia that could potentially be applied to predict outcome in the clinical setting, particularly in the large group of patients with favorable prognosis.Key words: LPL, RNA-based markers, chronic lymphocytic leukemia, prognosis.Citation: Kaderi MA, Kanduri M, Buhl AM, Sevov M, Cahill N, Gunnarsson R, Jansson M, Smedby KE, Hjalgrim H, Jurlander J, Juliusson G, Mansouri L, and Rosenquist R. LPL is the strongest prognostic factor in a comparative analysis of RNA-based markers in early chronic lymphocytic leukemia.

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Chronic lymphocytic leukemia (CLL) is most often indolent at diagnosis but has a highly variable clinical course, and many patients will eventually progress and require treatment. Currently, there are a number of clinical and molecular markers known to be predictive of prognosis in CLL that can be applied to discriminate patients that are more likely to develop a progressive disease. Gene-expression profiling studies have identified genes with differential expression between prognostic subgroups in CLL, and research on these RNA-based prognostic markers has expanded during recent years. For example, high lipoprotein lipase and CLLU1 mRNA expression have recently been shown to be strong markers of poor clinical outcome. In this review we will provide a summary of the most significant prognostic markers in CLL, focusing on the recent category of RNA-based markers in particular.