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Neurofibromatosis type 1 (NF1) is caused by NF1 gene mutations. The phenotype is highly variable, with ‘modifiers’ being discussed as potential determinants. Mismatch repair deficiency was shown to cause NF1 mutations, but constitutional mutation of mismatch repair genes was identified only once in a NF1 patient. We aimed to analyze whether DNA methylation of mismatch repair gene promoters, known to lead to transcriptional silencing, is associated with increased tumor load in NF1 defined by the number of cutaneous neurofibromas. Leukocyte DNA of 79 controls and 79 NF1 patients was investigated for methylation of mismatch repair genes MLH1, MSH2, MSH6, and PMS2 by methylation-specific PCR and pyrosequencing. MLH1, MSH6, and PMS2 promoters were not methylated. By contrast, we found promoter methylation of MSH2 with a higher rate of methylation in NF1 patients compared with controls. Furthermore, when comparing NF1 patients with a low vs those with a high number of cutaneous neurofibromas, MSH2 promoter methylation was significantly different. In patients with a high tumor burden, methylation of two (out of six) CpGs was enhanced. This finding was not confounded by age. In conclusion, enhanced methylation involving transcription start points of mismatch repair genes, such as MSH2 in NF1, has not been described so far. Methylation-induced variability of MSH2 gene expression may lead to variable mismatch repair capacity. Our results may point toward a role of MSH2 as a modifier for NF1, although the amount of DNA methylation and subsequent gene expression in other cell types of NF1 patients needs to be elucidated. [ABSTRACT FROM AUTHOR]

Noonan syndrome (NS) and cardio-facio-cutaneous syndrome (CFCS) are related developmental disorders caused by mutations in genes encoding various components of the RAS-MAPK signaling cascade. NS is associated with mutations in the genes PTPN11, SOS1, RAF1, or KRAS, whereas CFCS can be caused by mutations in BRAF, MEK1, MEK2, or KRAS. The NS phenotype is rarely accompanied by multiple giant cell lesions (MGCL) of the jaw (Noonan-like/MGCL syndrome (NL/MGCLS)). PTPN11 mutations are the only genetic abnormalities reported so far in some patients with NL/MGCLS and in one individual with LEOPARD syndrome and MGCL. In a cohort of 75 NS patients previously tested negative for mutations in PTPN11 and KRAS, we detected SOS1 mutations in 11 individuals, four of whom had MGCL. To explore further the relevance of aberrant RAS-MAPK signaling in syndromic MGCL, we analyzed the established genes causing CFCS in three subjects with MGCL associated with a phenotype fitting CFCS. Mutations in BRAF or MEK1 were identified in these patients. All mutations detected in these seven patients with syndromic MGCL had previously been described in NS or CFCS without apparent MGCL. This study demonstrates that MGCL may occur in NS and CFCS with various underlying genetic alterations and no obvious genotype–phenotype correlation. This suggests that dysregulation of the RAS-MAPK pathway represents the common and basic molecular event predisposing to giant cell lesion formation in patients with NS and CFCS rather than specific mutation effects.European Journal of Human Genetics (2009) 17, 420–425; doi:10.1038/ejhg.2008.188; published online 15 October 2008 [ABSTRACT FROM AUTHOR]

Characterizes the coastal ocean environment at the South Florida Ocean Measurement Center, using observations from very high frequency (VHF) radar. Background on the concept of using high frequency and VHF radar pulses to probe surface ocean currents; Description of the experimental design using the VHF radar; Surface current observations.

Neurofibromatosis type I (NF1) is a common familial tumour syndrome with multiple clinical features such as neurofibromas, caf´-au-lait spots (CLS), iris Lisch nodules, axillary freckling, optic glioma, specific bone lesions and an increased risk of malignant tumours. It is caused by a wide spectrum of mutations affecting the NF1 gene. Most mutations result in the loss of one allele at the DNA, mRNA or protein level and thus in the loss of any function of the gene product neurofibromin. The idea of the simultaneous loss of several different neurofibromin functions has been postulated to explain the pleiotropic effects of its loss. However, we have identified a novel missense mutation in a family with a classical multi-symptomatic NF1 phenotype, including a malignant schwannoma, that specifically abolishes the Ras-GTPase-activating function of neurofibromin. In this family, Arg1276 had mutated into proline. Based on complex biochemical studies as well as the analysis of the crystal structure of the GTPaseactivating protein (GAP) domain of p120GAP in the presence of Ras, we unequivocally identified this amino acid as the arginine finger of the neurofibromin GAP-related domain (GRD)—the most essential catalytic element for RasGAP activity. Here, we present data demonstrating that the mutation R1276P, unlike previously reported missense mutations of the GRD region, does not impair the secondary and tertiary protein structure. It neither reduces the level of cellular neurofibromin nor influences its binding to Ras substantially, but it does completely disable GAP activity. Our findings provide direct evidence that failure of neurofibromin GAP activity is the critical element of NF1 pathogenesis. Thus, therapeutic approaches aimed at the reduction of Ras. GTP levels in neural crest-derived cells can be expected to relieve most of the NF1 symptoms. [ABSTRACT FROM AUTHOR]

Examines the mutational spectrum of the entire neurofibromatosis type 1 gene. Aberrations in the coding sequence and splice sites; Distribution of whole gene from exon 1 to exon 47; Identification of clustered missense in two genetic regions.

Hay-Wells syndrome is a rare form of ectodermal dysplasia, also known as AEC syndrome (Ankyloblepharon filiforme adnatum, Ectodermal effects, Cleft lip/palate). It is inherited in an autosomal dominant fashion with variable expression, featuring congenital abnormalities of skin, hair, teeth, nail, eccrine and mucous glands. We present a three-month-old boy, born to unaffected parents, with typical clinical findings of AEC syndrome. In this boy, a mutation Ile537Thr (c.1610C>T) in the sterile alpha motive (SAM) domain of the TP73L (p63) gene was detected. Because of the broad spectrum of related syndromes such as Rapp-Hodgkin syndrome, Bowen-Armstrong syndrome, CHAND syndrome and epidermolysis bullosa hereditaria, the diagnosis of AEC should be base don both clinical findings and genetic analysis.

Our studies involved 21 women of Caucasian descent with PCOS, as diagnosed by ultrasound, clinical and hormonal findings. We determined 17alpha-OHP, 21-DOF and cortisol levels both just before and one hour after intravenous ACTH administration (0.25 mg Synacthen) in addition to the basal plasma levels of DHEA-S and free testosterone. We screened the CYP21 gene for 12 common-point mutations, finding five heterozygous mutations in 4 out of 21 cases (19%): a splice-site mutation in intron 2 in three cases, and a I172N mutation in exon 4 in two cases. These patients also displayed significantly higher 21-DOF or 17alpha-OHP plasma levels after ACTH administration, suggesting a partial 21-hydroxylase deficiency. Furthermore, we found the basal plasma DHEA-S levels or DHEA-S/F ratios in 11 of 21 patients (52%) to be higher than the means + 2SD of control females, indicating partial 3beta-HSD deficiency or 17,20-LHA. According to the literature, mutations could not be found in the genes of PCO cases with hormonal activity changes in the last two enzymes. The DDT metabolite o,p'-DDD is a strong inhibitor of 3beta-HSD, and DDT can induce 17,20-LHA, implying a possible connection between cases of PCOS women born in East Germany after 1955 and their prenatal DDT uptake. The approximately fourfold higher prevalence of PCO and significantly increased frequency of 3beta-HSD-deficiency and 17,20-LHA found in women with PCOS born since 1955-the time of massive application of DDT-give weight to the thesis that DDT, rather than genetic factors, has played a part in this upsurge.