Genetic modifiers of neurofibromatosis type 1-associated café-au-lait macule count identified using multi-platform analysis.

Neurofibromatosis type 1 (NF1) is an autosomal dominant, monogenic disorder of dysregulated neurocutaneous tissue growth. Pleiotropy, variable expressivity and few NF1 genotype-phenotype correlates limit clinical prognostication in NF1. Phenotype complexity in NF1 is hypothesized to derive in part from genetic modifiers unlinked to the NF1 locus. In this study, we hypothesized that normal variation in germline gene expression confers risk for certain phenotypes in NF1. In a set of 79 individuals with NF1, we examined the association between gene expression in lymphoblastoid cell lines with NF1-associated phenotypes and sequenced select genes with significant phenotype/expression correlations. In a discovery cohort of 89 self-reported European-Americans with NF1 we examined the association between germline sequence variants of these genes with café-au-lait macule (CALM) count, a tractable, tumor-like phenotype in NF1. Two correlated, common SNPs (rs4660761 and rs7161) between DPH2 and ATP6V0B were significantly associated with the CALM count. Analysis with tiled regression also identified SNP rs4660761 as significantly associated with CALM count. SNP rs1800934 and 12 rare variants in the mismatch repair gene MSH6 were also associated with CALM count. Both SNPs rs7161 and rs4660761 (DPH2 and ATP6V0B) were highly significant in a mega-analysis in a combined cohort of 180 self-reported European-Americans; SNP rs1800934 (MSH6) was near-significant in a meta-analysis assuming dominant effect of the minor allele. SNP rs4660761 is predicted to regulate ATP6V0B, a gene associated with melanosome biology. Individuals with homozygous mutations in MSH6 can develop an NF1-like phenotype, including multiple CALMs. Through a multi-platform approach, we identified variants that influence NF1 CALM count.

Genome-wide association study of café-au-lait macule number in neurofibromatosis type 1.

BACKGROUND: Neurofibromatosis type 1 (NF1) is a tumor-predisposition disorder that arises due to pathogenic variants in tumor suppressor NF1. NF1 has variable expressivity that may be due, at least in part, from heritable elements such as modifier genes; however, few genetic modifiers have been identified to date. METHODS: In this study, we performed a genome-wide association analysis of the number of café-au-lait macules (CALM) that are considered a tumor-like trait as a clinical phenotype modifying NF1. RESULTS: A borderline genome-wide significant association was identified in the discovery cohort (CALM1, N = 112) between CALM number and rs12190451 (and rs3799603, r2  = 1.0; p = 7.4 × 10-8 ) in the intronic region of RPS6KA2. Although, this association was not replicated in the second cohort (CALM2, N = 59) and a meta-analysis did not show significantly associated variants in this region, a significant corroboration score (0.72) was obtained for the RPS6KA2 signal in the discovery cohort (CALM1) using Complementary Pairs Stability Selection for Genome-Wide Association Studies (ComPaSS-GWAS) analysis, suggesting that the lack of replication may be due to heterogeneity of the cohorts rather than type I error. CONCLUSION: rs12190451 is located in a melanocyte-specific enhancer and may influence RPS6KA2 expression in melanocytes-warranting further functional studies.

Silanediol-Catalyzed Chromenone Functionalization.

Promising levels of enantiocontrol are observed in the silanediol-catalyzed addition of silyl ketene acetals to benzopyrylium triflates. This rare example of enantioselective, intermolecular chromenone functionalization with carbonyl-containing nucleophiles has potential applications in the synthesis of bioactive chromanones and tetrahydroxanthones.

Cephalometry in adults and children with neurofibromatosis type 1: Implications for the pathogenesis of sphenoid wing dysplasia and the "NF1 facies".

BACKGROUND: Neurofibromatosis type 1 (NF1) is a common, autosomal dominant tumor-predisposition disorder that arises secondary to mutations in the tumor suppressor gene NF1. Cephalometry is an inexpensive, readily available and non-invasive technique that is under-utilized in studying the NF1 craniofacial phenotype. An analysis of NF1 cephalometry was first published by Heervä et al. in 2011. We expand here on that first investigation with a larger cohort of adult and pediatric patients affected with NF1 and sought objective insight into the NF1 facies, said to feature hypertelorism and a broad nasal base, from cephalometric analysis. METHODS: We obtained cephalograms from 101 patients with NF1 (78 adults and 23 children) from two NF1 protocols at the National Institutes of Health. Each subject had an age-, gender- and ethnicity-matched control. We used Dolphin software to make the cephalometric measurements. We assessed the normality of differences between paired samples using the Shapiro-Wilk test and evaluated the significance of mean differences using paired t-tests and adjusted for multiple testing. We explored the relationship between the cephalometric measurements and height, head circumference and interpupillary distance. RESULTS: In this dataset of American whites with NF1, we confirmed in a modestly larger sample many of the findings found by Heerva et al. in an NF1 Finnish cohort. We found a shorter maxilla, mandible, cranial base, (especially anteriorly, p = 0.0001) and diminished facial height in adults, but not children, with NF1. Only one adult exhibited hypertelorism. CONCLUSIONS: The cephalometric differences in adults arise in part from cranial base shortening and thus result in a shorter face, mid-face hypoplasia, reduced facial projection, smaller jaw, and increased braincase globularity. In addition, we suggest that NF1 sphenoid bone shortening, a common event, is consistent with an intrinsic NF1 bone cell defect, which renders the bone more vulnerable to a random "second hit" in NF1, leading to sphenoid wing dysplasia, a rare event.

Silanediol-catalyzed carbon dioxide fixation.

Carbon dioxide is an abundant and renewable C1 source. However, mild transformations with carbon dioxide at atmospheric pressure are difficult to accomplish. Silanediols have been discovered to operate as effective hydrogen-bond donor organocatalysts for the atom-efficient conversion of epoxides to cyclic carbonates under environmentally friendly conditions. The reaction system is tolerant of a variety of epoxides and the desired cyclic carbonates are isolated in excellent yields.

Visual outcomes in children with neurofibromatosis type 1 and orbitotemporal plexiform neurofibromas.

PURPOSE: To describe the visual outcomes and volumetric magnetic resonance imaging (3D MRI) in children with neurofibromatosis type 1 (NF1) and orbitotemporal plexiform neurofibromas. DESIGN: Multicenter retrospective case series. METHODS: Two institutions with dedicated NF1 clinical research programs queried their established clinical databases for children with orbitotemporal plexiform neurofibromas. Visual acuity, refractive error, ambylopia, and treatment history were abstracted. Extent of orbitotemporal plexiform neurofibroma involvement was assessed clinically and with 3D MRI analysis. Children with optic pathway gliomas or ocular causes of decreased visual acuity (ie, cataracts, glaucoma) other than strabismus or anisometropia were excluded. RESULTS: Twenty-one children met inclusion criteria (median age 8 years, range 0.33-23 years). Orbitotemporal plexiform neurofibroma location was classified as isolated eyelid (n = 6), eyelid and orbit (n = 7), orbit and temporal region (n = 7), or diffuse orbit (n = 1). Three subjects had bilateral orbital involvement. Amblyopia secondary to the orbitotemporal plexiform neurofibroma was present in 13 subjects (62%) and was caused by strabismus (n = 2, 10%), occlusion from ptosis (n = 9, 43%), or anisometropia (n = 9, 43%), or a combination of factors (n = 6, 29%). MRI-derived volumes were measured in 19 subjects (median 41.8 mL, range 2.7-754 mL). All subjects with amblyopia had orbitotemporal plexiform neurofibroma volumes greater than 10 mL. CONCLUSION: In our series, amblyopia occurs in more than half of NF1 children with orbitotemporal plexiform neurofibromas, most commonly because of ptosis and anisometropia. The 3D MRI analysis allowed for sensitive measurement of orbitotemporal plexiform neurofibroma size, and larger volumes were associated with development of amblyopia.

Bone mineral density in children and young adults with neurofibromatosis type 1.

Concern for impaired bone health in children with neurofibromatosis type 1 (NF-1) has led to increased interest in bone densitometry in this population. Our study assessed bone mineral apparent density (BMAD) and whole-body bone mineral content (BMC)/height in pediatric patients with NF-1 with a high plexiform neurofibroma burden. Sixty-nine patients with NF-1 (age range 5.2-24.8; mean 13.7 ± 4.8 years) were studied. Hologic dual-energy X-ray absorptiometry scans (Hologic, Inc., Bedford, MA, USA) were performed on all patients. BMD was normalized to derive a reference volume by correcting for height through the use of the BMAD, as well as the BMC. BMAD of the lumbar spine (LS 2-4), femoral neck (FN), and total body BMC/height were measured and Z-scores were calculated. Impaired bone mineral density was defined as a Z-score ≤-2. Forty-seven percent of patients exhibited impaired bone mineral density at any bone site, with 36% at the LS, 18% at the FN, and 20% total BMC/height. BMAD Z-scores of the LS (-1.60 ± 1.26) were more impaired compared with both the FN (-0.54 ± 1.58; P=0.0003) and the whole-body BMC/height Z-scores (-1.16 ± 0.90; P=0.036). Plexiform neurofibroma burden was negatively correlated with LS BMAD (r(s)=-0.36, P=0.01). In pediatric and young adult patients with NF-1, LS BMAD was more severely affected than the FN BMAD or whole-body BMC/height.