Li Yao

CONTEXT: Pheochromocytomas and paragangliomas are genetically heterogeneous neural crest-derived neoplasms. We recently identified germline mutations of the novel transmembrane-encoding gene FP/TMEM127 in familial and sporadic pheochromocytomas consistent with a tumor suppressor effect. OBJECTIVES: To examine the prevalence and spectrum of FP/TMEM127 mutations in pheochromocytomas and paragangliomas and to test the effect of mutations in vitro. DESIGN, SETTING, AND PARTICIPANTS: We sequenced the FP/TMEM127 gene in 990 individuals with pheochromocytomas and/or paragangliomas, including 898 previously unreported cases without mutations in other susceptibility genes from 8 independent worldwide referral centers between January 2009 and June 2010. A multiplex polymerase chain reaction-based method was developed to screen for large gene deletions in 545 of these samples. Confocal microscopy of 5 transfected mutant proteins was used to determine their subcellular localization. MAIN OUTCOME MEASURES: The frequency and type of FP/TMEM127 mutation or deletion was assessed and correlated with clinical variables; the subcellular localization of 5 overexpressed mutants was compared with wild-type FP/TMEM127 protein. RESULTS: We identified 19 potentially pathogenic FP/TMEM127 germline mutations in 20 independent families, but no large deletions were detected. All mutation carriers had adrenal tumors, including 7 bilateral (P = 2.7 × 10(-4)) and/or with familial disease (5 of 20 samples; P = .005). The median age at disease onset in the FP/TMEM127 mutation group was similar to that of patients without a mutation (41.5 vs 45 years, respectively; P = .54). The most common presentation was that of a single benign adrenal tumor in patients older than 40 years. Malignancy was seen in 1 mutation carrier (5%). Expression of 5 novel FP/TMEM127 mutations in cell lines revealed diffuse localization of the mutant proteins in contrast with the discrete multiorganelle distribution of wild-type TMEM127. CONCLUSIONS: Germline mutations of FP/TMEM127 were associated with pheochromocytoma but not paraganglioma and occurred in an age group frequently excluded from genetic screening algorithms. Disease-associated mutations disrupt intracellular distribution of the FP/TMEM127 protein.

CONTEXT: Pheochromocytomas and paragangliomas are genetically heterogeneous tumors of neural crest origin. Approximately half of these tumors activate a pseudohypoxic transcription response, which is due in a minority of the cases to germline mutations of the VHL gene or the genes encoding subunits of the metabolic enzyme succinate dehydrogenase (SDH), SDHB, SDHC, or SDHD. However, the genetic basis of the hypoxic-like profile of the remaining tumors is undetermined. Mutations in genes involved in the energy metabolism, isocitrate dehydrogenase 1 (IDH1) and -2 (IDH2) and SDHAF2, a component of SDH, can mimic a pseudohypoxic state. DESIGN: We examined the sequence spanning the mutation-susceptible codons 132 of IDH1 and 172 of IDH2, and the entire coding region of SDHAF2, in 104 pheochromocytomas and paragangliomas, including tumors with a pseudohypoxic expression profile. RESULTS: We did not find mutations in IDH1, IDH2, or SDHAF2 in any of the tumors in this cohort. CONCLUSION: Conserved residues of IDH1 and IDH2 or the SDHAF2 gene are not frequently mutated in pheochromocytomas and paragangliomas. The molecular basis for activation of a hypoxic response in the majority of tumors without VHL or SDH mutations remains to be defined.

PURPOSE: To evaluate the efficacy of next-generation sequencing (NGS) in minimal-residual-disease (MRD) monitoring in Chinese patients with multiple myeloma (MM). METHODS: This study analyzed 60 Chinese MM patients. During MRD monitoring in these patients' post-therapy, clonal immunoglobulin heavy chain (IGH) rearrangements were detected via NGS using LymphoTrack assays. MRD monitoring was performed using NGS or next-generation flow cytometry (NGF), and the results were compared. Additionally, the sensitivity and reproducibility of the NGS method were assessed. RESULTS: . Intra- and inter-assay reproducibility analyses showed that NGS exhibited 100% reproducibility with low variability in clonal cells. At diagnosis, unique clones were found in 42 patients (70.0%) with clonal IGH rearrangements, which were used as clonality markers for MRD monitoring post-therapy. Comparison of NGS and NGF for MRD monitoring showed 79.1% concordance. No samples that tested MRD-positive via NGF were found negative via NGS, indicating the higher sensitivity of NGS. MRD could be detected using NGS in 6 of 7 samples before autologous hematopoietic stem-cell transplantation, and 5 of them tested negative post-transplantation. In contrast, the NGF method could detect MRD in only 1 sample pre-transplantation. CONCLUSION: Compared with NGF, NGS exhibits higher sensitivity and reproducibility in MRD detection and can be an effective strategy for MRD monitoring in Chinese MM patients.

Multiple myeloma (MM) is a heterogeneous disease, the full understanding of whose pathogenesis remains elusive. While B-cell receptors are known to play a pivotal role in myeloma pathogenesis, the characterization of immunoglobulin heavy-chain (IGH) gene repertoire and their clinical significance in Chinese patients has not been fully explored. In this study, we analyzed the profiling of clonal IGH gene rearrangements via NGS assay, and its cytogenetic abnormalities by FISH in a cohort of 301 Chinese patients with newly diagnosed MM. We identified a particular subgroup, which was characterized by a marked overrepresentation of IGHV4-39. Additionally, IGHV4-39 was correlated with a higher somatic hypermutation rate and shorter HCDR3 length. Notably, IGHV4-39 was significantly more prevalent in patients with high-risk cytogenetic abnormalities, particularly the recurrent IGH translocations involving t(4;14). Our findings, represented the largest IGH data in MM series from Asia, and investigated the association between specific IGHV and cytogenetic alterations in Chinese MM patients for the first time.