Emergence of new ALK mutations at relapse of neuroblastoma.

PURPOSE: In neuroblastoma, the ALK receptor tyrosine kinase is activated by point mutations. We investigated the potential role of ALK mutations in neuroblastoma clonal evolution. METHODS: We analyzed ALK mutations in 54 paired diagnosis-relapse neuroblastoma samples using Sanger sequencing. When an ALK mutation was observed in one paired sample, a minor mutated component in the other sample was searched for by more than 100,000× deep sequencing of the relevant hotspot, with a sensitivity of 0.17%. RESULTS: All nine ALK-mutated cases at diagnosis demonstrated the same mutation at relapse, in one case in only one of several relapse nodules. In five additional cases, the mutation seemed to be relapse specific, four of which were investigated by deep sequencing. In two cases, no mutation evidence was observed at diagnosis. In one case, the mutation was present at a subclonal level (0.798%) at diagnosis, whereas in another case, two different mutations resulting in identical amino acid changes were detected, one only at diagnosis and the other only at relapse. Further evidence of clonal evolution of ALK-mutated cells was provided by establishment of a fully ALK-mutated cell line from a primary sample with an ALK-mutated cell population at subclonal level (6.6%). CONCLUSION: In neuroblastoma, subclonal ALK mutations can be present at diagnosis with subsequent clonal expansion at relapse. Given the potential of ALK-targeted therapy, the significant spatiotemporal variation of ALK mutations is of utmost importance, highlighting the potential of deep sequencing for detection of subclonal mutations with a sensitivity 100-fold that of Sanger sequencing and the importance of serial samplings for therapeutic decisions.

Does modern high standard life style cause type 1 diabetes in children?

BACKGROUND: Type 1 diabetes is a serious disease which, in spite of intensive treatment, causes serious complications and increased mortality. The incidence is increasing, but the aetiology is unknown. As part of modern lifestyle, increased hygiene has been suspected as one contributing cause but so far there is no evidence. Several large epidemiological studies, mainly restricted to children with increased genetic risk for type 1 diabetes, have so far given no clue. METHODS: All Babies in Southeast Sweden is unique in its design as it has followed an unselected group of children from birth 1997-1999 and onwards with regular follow-ups. This report is based on questionnaires from initially 16 051 children of whom 80 have later on developed type 1 diabetes. The parents answered questionnaires at the birth of their child and then after 1, 2-3, 5-6 and 8 years. A number of parameters possibly related to hygiene were analysed with several statistical methods, both with univariate and in regression models. RESULTS: Our study cannot identify any crucial environmental factor. This indicates that hygiene-related parameters traditionally regarded as part of 'modern life style' do not play any important role for the aetiology of type 1 diabetes. CONCLUSIONS: There is no reason to recommend a change of that part of our lifestyle. We find weak associations to previous gastrointestinal infections, which gives a hint that development of type 1 diabetes may be related to problems in the gut and maybe one should look closer into the microbes living in the gut.

Familial hemophagocytic lymphohistiocytosis type 3 (FHL3) caused by deep intronic mutation and inversion in UNC13D.

Familial hemophagocytic lymphohistiocytosis (FHL) is an autosomal recessive, often-fatal hyperinflammatory disorder. Mutations in PRF1, UNC13D, STX11, and STXBP2 are causative of FHL2, 3, 4, and 5, respectively. In a majority of suspected FHL patients from Northern Europe, sequencing of exons and splice sites of such genes required for lymphocyte cytotoxicity revealed no or only monoallelic UNC13D mutations. Here, in 21 patients, we describe 2 pathogenic, noncoding aberrations of UNC13D. The first is a point mutation localized in an evolutionarily conserved region of intron 1. This mutation selectively impairs UNC13D transcription in lymphocytes, abolishing Munc13-4 expression. The second is a 253-kb inversion straddling UNC13D, affecting the 3'-end of the transcript and likewise abolishing Munc13-4 expression. Carriership of the intron 1 mutation was found in patients across Europe, whereas carriership of the inversion was limited to Northern Europe. Notably, the latter aberration represents the first description of an autosomal recessive human disease caused by an inversion. These findings implicate an intronic sequence in cell-type specific expression of Munc13-4 and signify variations outside exons and splice sites as a common cause of FHL3. Based on these data, we propose a strategy for targeted sequencing of evolutionary conserved noncoding regions for the diagnosis of primary immunodeficiencies.