Enhancer hijacking determines extrachromosomal circular MYCN amplicon architecture in neuroblastoma

MYCN amplification drives one in six cases of neuroblastoma. The supernumerary gene copies are commonly found on highly rearranged, extrachromosomal circular DNA (ecDNA). The exact amplicon structure has not been described thus far and the functional relevance of its rearrangements is unknown. Here, we analyze the MYCN amplicon structure using short-read and Nanopore sequencing and its chromatin landscape using ChIP-seq, ATAC-seq and Hi-C. This reveals two distinct classes of amplicons which explain the regulatory requirements for MYCN overexpression. The first class always co-amplifies a proximal enhancer driven by the noradrenergic core regulatory circuit (CRC). The second class of MYCN amplicons is characterized by high structural complexity, lacks key local enhancers, and instead contains distal chromosomal fragments harboring CRC-driven enhancers. Thus, ectopic enhancer hijacking can compensate for the loss of local gene regulatory elements and explains a large component of the structural diversity observed in MYCN amplification. MYCN amplification is common in neuroblastomas. Here the authors analyse the MYCN amplicon structure and its epigenetic regulation by integrating short- and longread genomic and epigenomic data and find two classes of MYCN amplicons in neuroblastomas, one driven by local enhancers and the other by hijacking of distal regulatory elements

Age Adjustment Corrects for Apparent Differences in Erythrocyte Sedimentation Rate and C-Reactive Protein Values at the Onset of Seropositive Rheumatoid Arthritis in Younger and Older Patients

ABSTRACT. Objective. To evaluate the effect of age adjustment on baseline erythrocyte sedimentation rate (ESR) and C-reactive protein (CRP) in patients with late-onset rheumatoid arthritis (LORA, age ≥ 55 yrs) and younger-onset RA (YORA, age < 55 yrs) in a cohort with early, rheumatoid factor (RF) positive RA that has not received disease modifying antirheumatic drugs (DMARD). Methods. In an ongoing prospective cohort study of 263 patients with seropositive RA who were enrolled within 14 months of symptom onset, baseline assessments included ESR, CRP, tender and swollen joint counts, and functional status. Westergren ESR determinations were performed in the rheumatologist's office or in a local laboratory using appropriate methods. CRP were performed at the Specialty Laboratories in Santa Monica, CA, using Behring nephelometry. Percentages of patients with greater than the upper limit of normal (ULN) laboratory values using both age-unadjusted and age-adjusted ESR and CRP values were determined. The late-onset and younger-onset RA patients were compared using Wilcoxon rank-sum and chi-square tests. Results. At study entry, both the YORA and LORA patients had comparable symptom duration, disease activity scores, tender and swollen joint counts, and Health Assessment Questionnaire values. RF, CRP, and ESR were significantly higher (p < 0.05) in LORA patients. Although the percentages of patients with age-unadjusted ESR and CRP above ULN were higher in LORA patients, the percentages exceeding the age-adjusted ULN did not differ significantly between the YORA and LORA groups. Conclusion. In patients with late-onset and younger-onset RA with similar disease duration and severity, the apparent discrepancy in elevation of both the baseline ESR and CRP disappears after age-adjustment. (J Rheumatol 2005;32:1040-2