Characteristics of 2p15‐p16.1 microdeletion syndrome: Review and description of two additional patients

Many new microdeletion syndromes have been characterized in the past decade, including 2p15‐p16.1 microdeletion syndrome. More than 10 patients with this syndrome have been described. Recently, we encountered two additional patients with 2p15‐p16.1 microdeletion syndrome. All patients showed variable degrees of intellectual disability, with the autistic features characteristic of this syndrome. Seven out of 16 patients (44%) showed structural abnormalities in the brain, which is also an important feature of this syndrome. The shortest region of microdeletion overlap among the patients includes two genes, USP34 and XPO1. Although these genes have some functional relevance to cancer, they have not been associated with neurological functions. Diagnosis of additional patients with 2p15‐p16.1 microdeletion syndrome and identification of pathogenic mutations in this region will help identify the genes responsible for the neurological features of the syndrome.     

Multifactorial analysis of opsoclonus‐myoclonus syndrome etiology (“Tumor” vs. “No tumor”) in a cohort of 356 US children

1 Background

Pediatric opsoclonus‐myoclonus syndrome (OMS) presents a paradox of etiopathogenesis: A neuroblastic tumor (NB) is found in only one half of the cases, the others are ascribed to infections or designated as idiopathic.

2 Method

From an IRB‐approved observational study of 356 US children with OMS, secondary analysis of “etiology” and related factors was performed on a well‐characterized cohort. The “Tumor” (n = 173) and “No Tumor” groups (n = 183), as defined radiologically, were compared according to multiple factors considered potentially differentiating. Data were analyzed retrospectively using parametric and nonparametric tests as indicated.

3 Results

Patients with NB were not distinguishable by prodromal symptoms, OMS onset age, gender, race/ethnicity, OMS severity, rank order of neurological sign appearance, or geographic distribution. Various CSF immunologic biomarker abnormalities of OMS did not vary in the presence or absence of a detectable tumor: frequency of six lymphocyte subsets, or concentrations of 18 cytokines/chemokines, cytokine antagonists, chemokine receptors, cell adhesion molecules, or neuronal/glial markers. Prior responsiveness to conventional immunotherapy was not contingent on tumor/no tumor designation.

4 Conclusions

Multiple convergent factors provide compelling empirical evidence and rationalize the concept that OMS is one neurological disorder, regardless of apparent etiology. Limitations to the current clinical etiologic classifications as paraneoplastic, parainfectious/post‐infectious, and idiopathic etiology require antigen‐based biological solutions to tease out the molecular pathophysiology of viral/tumoral mechanisms. Systematic studies, regardless of presumed etiology, will be necessary to find the highest‐yield combination of imaging approaches, screening for infectious agents, and new biomarkers. Two testable hypotheses for future research are presented.     

The challenge of defining “ultra‐high‐risk” neuroblastoma

Given the biological and clinical heterogeneity of neuroblastoma, risk stratification is vital to determining appropriate treatment. Historically, most patients with high‐risk neuroblastoma (HR‐NBL) have been treated uniformly without further stratification. Attempts have been made to identify factors that can be used to risk stratify these patients and to characterize an “ultra‐high‐risk” (UHR) subpopulation with particularly poor outcome. However, among published data, there is a lack of consensus in the definition of the UHR population and heterogeneity in the endpoints and statistical methods used. This review summarizes our current understanding of stratification of HR‐NBL and discusses the complex issues in defining UHR neuroblastoma.