Noonan syndrome (NS) is a common, clinically and genetically heterogeneous condition characterized by distinctive facial features, short stature, chest deformity, congenital heart disease, and other comorbidities. Gene mutations identified in individuals with the NS phenotype are involved in the Ras/MAPK (mitogen-activated protein kinase) signal transduction pathway and currently explain ∼61% of NS cases. Thus, NS frequently remains a clinical diagnosis. Because of the variability in presentation and the need for multidisciplinary care, it is essential that the condition be identified and managed comprehensively. The Noonan Syndrome Support Group (NSSG) is a nonprofit organization committed to providing support, current information, and understanding to those affected by NS. The NSSG convened a conference of health care providers, all involved in various aspects of NS, to develop these guidelines for use by pediatricians in the diagnosis and management of individuals with NS and to provide updated genetic findings.

Germline mutations at loci encoding the transcription factor Microphthalmia (Mi), the cytokine receptor c-Kit, or its ligand Steel factor (S1) result in strikingly similar defects in mast cell and melanocyte development. Here we describe a biochemical link between Kit signalling and the activity of Mi. Stimulation of melanoma cells with S1 results in activation of MAP kinase, which in turn phosphorylates Mi at a consensus target serine. This phosphorylation upregulates Mi transactivation of the tyrosinase pigmentation gene promoter. In addition to modulating pigment production, such signalling may regulate the expression of genes essential for melanocyte survival and development. The pathway represents a new application of the general MAP kinase machinery in transducing a signal between a tissue-specific receptor at the cell surface and a tissue-specific transcription factor in the nucleus.

Juvenile myelomonocytic leukemia (JMML) is a myeloproliferative neoplasm (MPN) of childhood with a poor prognosis. Mutations in NF1, NRAS, KRAS, PTPN11 and CBL occur in 85% of patients, yet there are currently no risk stratification algorithms capable of predicting which patients will be refractory to conventional treatment and therefore be candidates for experimental therapies. In addition, there have been few other molecular pathways identified aside from the Ras/MAPK pathway to serve as the basis for such novel therapeutic strategies. We therefore sought to genomically characterize serial samples from patients at diagnosis through relapse and transformation to acute myeloid leukemia in order to expand our knowledge of the mutational spectrum in JMML. We identified recurrent mutations in genes involved in signal transduction, gene splicing, the polycomb repressive complex 2 (PRC2) and transcription. Importantly, the number of somatic alterations present at diagnosis appears to be the major determinant of outcome.

No abstract

SignificanceThis study defines clinical indications for using telomere length (TL) measurement as a diagnostic tool in a hospital setting. It shows that, in contrast to other methods, TL measurement by flow cytometry and FISH (flowFISH) can be standardized, and has reproducible and definable upper and lower normal boundaries. In telomerase mutation carriers and carriers of other mutant telomere maintenance genes, TL had prognostic value, correlating with the age of onset of short telomeres syndrome phenotypes, as well as the predominant complication. In a prospective study, TL results were actionable in one-fourth of cases with idiopathic bone marrow failure affecting the stem cell donor choice and/or treatment regimen. The data show that, for targeted clinical indications, and in a hospital setting, TL measurement by flowFISH informs patient care decisions.

The pituitary peptide ␣-melanocyte-stimulating hormone (␣-MSH) stimulates melanocytes to up-regulate cAMP, but the downstream targets of cAMP are not well understood mechanistically. One consequence of ␣-MSH stimulation is increased melanization attributable to induction of pigmentation enzymes, including tyrosinase, which catalyzes a rate-limiting step in melanin synthesis. The tyrosinase promoter is a principle target of the melanocyte transcription factor Microphthalmia (Mi), a factor for which deficiency in humans causes Waardenburg syndrome II. We show here that both ␣-MSH and forskolin, a drug that increases cAMP, stimulate a rapid increase in Mi mRNA and protein levels in both melanoma cell lines and primary melanocytes. This up-regulation requires a cAMP-responsive element within the Mi promoter, and the pathway leading to Mi stimulation is subject to tight homeostatic regulation. Although cAMP signaling is ubiquitous, the Mi promoter was seen to be cAMP-responsive in melanocytes but not in nonmelanocytes. Moreover, dominant negative interference with Mi impeded successful ␣-MSH stimulation of tyrosinase. The regulation of Mi expression via ␣-MSH thus provides a direct mechanistic link to pigmentation. In addition, because the human melanocyte and deafness condition Waardenburg syndrome is sometimes caused by haploinsufficiency of Mi, its modulation by ␣-MSH suggests therapeutic strategies targeted at up-regulating the remaining wild type Mi allele.Waardenburg syndrome II is a human dominant hereditary pigmentation and deafness condition in which mutations in the Microphthalmia (Mi) 1 transcription factor gene have been identified (1-3). Homozygous microphthalmia mutations in mice result in complete absence of the melanocyte lineage (4), which permitted identification and cloning of Mi (5-7). It is thought that inner ear melanocytes are functionally deficient in Waardenburg patients, suggesting an essential although poorly understood role for pigment cells in sensorineural hearing. Most human mutations in Mi are likely to be functionally null (1-3) based largely on structure-function relationships previously examined in a series of murine Mi mutations (8,9). Because human Waardenburg Syndrome II often results from haploinsufficiency, it is of interest to understand pathways that might up-regulate Mi expression on the remaining (wild type) Mi allele.Recent work has demonstrated that Mi protein function is subject to regulation in response to cytokine signaling. Activation of the c-Kit cytokine receptor on pigment cells by Steel factor was found to trigger activation of mitogen-activated protein kinase, which directly phosphorylates Mi at serine 73 (10). The transcriptional activity of Mi is modulated through interactions with the transcriptional coactivator p300/CREB-binding protein (11), the specific recruitment to Mi of which is regulated by mitogen-activated protein kinase phosphorylation (12). c-Kit signaling thus increases histone acetyl transferase activity associated with Mi, significantly enhanc...

Turoctocog alfa pegol (N8-GP) is a novel glycoPEGylated extended half-life recombinant factor VIII (FVIII) product developed for prophylaxis and treatment of bleeds in patients with haemophilia A, to enable higher activity levels with less frequent injections compared with standard FVIII products. This phase III (NCT01480180), multinational, open-label, non-randomised trial evaluated the safety and clinical efficacy of N8-GP when administered for treatment of bleeds and for prophylaxis, in previously treated patients aged ≥12 years with severe haemophilia A. Patients were allocated to receive N8-GP for prophylaxis or on-demand treatment for up to 1.8 years. Patients on prophylaxis were administered one dose of 50 IU/kg of N8-GP every fourth day. Bleeds were treated with doses of 20-75 IU/kg. Total exposure to N8-GP in the trial was 14,114 exposure days (159 patient-years). For the prophylaxis arm (n=175), the median annualised bleeding rate (ABR) was 1.33 (interquartile range, 0.00-4.61), the mean ABR was 3.70 (95 % confidence interval 2.94-4.66) and 70 (40 %) patients had no bleeds during the trial. Across treatment arms, 83.6 % of bleeds resolved with one injection and 95.5 % with up to two injections. N8-GP had a favourable safety profile and was well tolerated. The frequency and types of adverse events reported were as expected in this population. One patient developed inhibitory antibodies against FVIII (≥0.6 Bethesda units [BU]) after 93 N8-GP exposure days. No clinically significant safety concerns were identified and N8-GP was effective for prophylaxis and treatment of bleeds in previously treated patients.

The results of this study suggest that perioperative RBC transfusions may be significantly associated with the development of new or progressive postoperative VTE, independent of several putative confounders. These findings, if validated, should reinforce the importance of rigorous perioperative management of blood transfusion practices.