Vogt et al. Journal of Medical Case Reports 2011, 5:577 http://www.jmedicalcasereports.com/content/5/1/577 manifestations of the disease are likely to be influenced not only by the deletion of the NF1 gene but also by the deletion of flanking genes. In contrast to type-1 dele- tions, the LRRC37B gene of unknown function is not included within the deletion interval of type-2 deletions (Figure 1). As yet, it is unclear whether haploinsuffi- ciency for the LRRC37B gene exerts any influence on the clinical phenotype associated with large NF1 dele- tions. In this context, it seems worthwhile to note that our two patients clinically investigated in this study did not exhibit severe mental retardation. In the study of Mautner et al. [5], 38% of patients with molecularly assigned type-1 NF1 deletions exhibited severe mental retardation. Further clinical investigations of additional patients with NF1 with non-mosaic type-2 NF1 deletions will be necessary in order to assess whether severe men- tal retardation is a feature that occurs more often in association with type-1 than type-2 NF1 deletions. Conclusions The clinical phenotype of patients with non-mosaic type-2 NF1 deletions can be severe and includes most of the features that have been reported in patients with type-1 NF1 deletions. Our findings support the existence of a NF1 microdeletion syndrome caused by type-1 as well as type-2 NF1 deletions. The additional complica- tions associated with the NF1 microdeletion syndrome render the intensive clinical and psychological care of patients who are affected absolutely necessary. Consent Written informed consent was obtained from the legal guardians/parents of both patients for publication of this case report and any accompanying images. A copy of the written consent is available for review by the Editor- in-Chief of this journal. Acknowledgements This work was supported by grants from the DFG (KE 724/9-1, KE724/7-1) and from the Deutsche Krebshilfe (#108793). JV holds a fellowship from the International Graduate School in Molecular Medicine, Ulm. Author details 1Institute of Human Genetics, University of Ulm, Ulm, Germany. 2Department of Pediatrics, University of Maryland, Baltimore, MD, USA. 3Department of Maxillofacial Surgery, University Medical Center Hamburg-Eppendorf, Hamburg, Germany. 4Institute of Medical Genetics, School of Medicine, Cardiff University, Cardiff, UK. 5Department of Neurosurgery, University of Tübingen, Tübingen, Germany. 6Department of Neurology, University Medical Center Hamburg-Eppendorf, Hamburg, Germany. Authors’ contributions JV, HK-S and DNC wrote the manuscript; RN, LK and V-FM performed the clinical investigations; ACR, JV and TM performed the mutation analysis. 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