Mapping of three novel loci for non‐syndromic autosomal recessive mental retardation (NS‐ARMR) in consanguineous families from Pakistan

Rafiq MA, Ansar M, Marshall CR, Noor A, Shaheen N, Mowjoodi A, Khan MA, Ali G, Amin‐ud‐Din M, Feuk L, Vincent JB, Scherer SW. Mapping of three novel loci for non‐syndromic autosomal recessive mental retardation (NS‐ARMR) in consanguineous families from Pakistan. To date, of 13 loci with linkage to non‐syndromic autosomal recessive mental retardation (NS‐ARMR), only six genes have been established with associated mutations. Here we present our study on NS‐ARMR among the Pakistani population, where people are traditionally bound to marry within the family or the wider clan. In an exceptional, far‐reaching genetic survey we have collected more than 50 consanguineous families exhibiting clinical symptoms/phenotypes of NS‐ARMR. In the first step, nine families (MR2‐9 and MR11) with multiple affected individuals were selected for molecular genetic studies. Two families (MR3, MR4) showed linkage to already know NS‐ARMR loci. Fifteen affected and 10 unaffected individuals from six (MR2, MR6, MR7, MR8, MR9 and MR11) families were genotyped by using Affymetrix 5.0 or 6.0 single‐nucleotide polymorphism (SNP) microarrays. SNP microarray data was visually inspected by dChip and genome‐wide homozygosity analysis was performed by HomozygosityMapper. Additional mapping was performed (to exclude false‐positive regions of homozygosity called by HomozygosityMapper and dChip) on all available affected and unaffected members in seven NS‐ARMR families, using microsatellite markers. In this manner we were able to map three novel loci in seven different families originating from different areas of Pakistan. Two families (MR2, MR5) showed linkage on chromosome 2p25.3‐p25.2. Three families (MR7, MR8, and MR9) that have been collected from the same village and belong to the same clan were mapped on chromosome 9q34.3. MR11 maps to a locus on 9p23‐p13.3. Analysis of MR6 showed two positive loci, on chromosome 1q23.2‐q23.3 and 8q24.21‐q24.23. Genotyping in additional family members has so far narrowed, but not excluded the 1q locus. In summary, through this study we have identified three new loci for NS‐ARMR, namely MRT14, 15 and 16.     

Directing the Self‐Assembly of Mesostructured Hybrid Materials: Effect of Polymer Concentration and Solvent Type

Herein we explore the possibility to control the fabrication of non‐equilibrium nano‐patterns of spin‐coated organic‐inorganic hybrid materials based on diblock copolymers and metal nanoparticles in thin films. It is demonstrated that the type of solvent and the initial solution concentration, among other factors, can serve as tools to direct the morphology of spin‐coated thin films. The driving forces leading to the pattern formation are reviewed with respect to these parameters—type of solvents and polymer concentration. As a result well‐defined surface patterns of functional hybrid materials are obtained. Moreover, the same tools used to direct the pattern formation can be applied to gain control over the particle size and size distribution.

     

Biology and grading of pleomorphic xanthoastrocytoma—what have we learned about it?

Pleomorphic xanthoastrocytoma (PXA) is a rare astrocytoma predominantly affecting children and young adults. We performed comprehensive genomic characterization on a cohort of 67 patients with histologically defined PXA (n = 53, 79%) or anaplastic PXA (A‐PXA, n = 14, 21%), including copy number analysis (ThermoFisher Oncoscan, n = 67), methylation profiling (Illumina EPIC array, n = 43) and targeted next generation sequencing (n = 32). The most frequent alterations were CDKN2A/B deletion (n = 63; 94%) and BRAF p.V600E (n = 51, 76.1%). In 7 BRAF p.V600 wild‐type cases, alternative driver alterations were identified involving BRAF, RAF1 and NF1. Downstream phosphorylation of ERK kinase was uniformly present. Additional pathogenic alterations were rare, with TERT, ATRX and TP53 mutations identified in a small number of tumors, predominantly A‐PXA. Methylation‐based classification of 46 cases utilizing a comprehensive reference tumor allowed assignment to the PXA methylation class in 40 cases. A minority grouped with the methylation classes of ganglioglioma or pilocytic astrocytoma (n = 2), anaplastic pilocytic astrocytoma (n = 2) or control tissues (n = 2). In 9 cases, tissue was available from matched primary and recurrent tumors, including 8 with anaplastic transformation. At recurrence, two tumors acquired TERT promoter mutations and the majority demonstrated additional non‐recurrent copy number alterations. Methylation class was preserved at recurrence. For 62 patients (92.5%), clinical follow‐up data were available (median follow‐up, 5.4 years). Overall survival was significantly different between PXA and A‐PXA (5‐year OS 80.8% vs. 47.6%; P = 0.0009) but not progression‐free survival (5‐year PFS 59.9% vs. 39.8%; P = 0.05). WHO grade remained a strong predictor of overall survival when limited to 38 cases defined as PXA by methylation‐based classification. Our data confirm the importance of WHO grading in histologically and epigenetically defined PXA. Methylation‐based classification may be helpful in cases with ambiguous morphology, but is largely confirmatory in PXA with well‐defined morphology.     

Microsatellite instability in pediatric and adult high-grade gliomas

About 15% of sporadic gastrointestinal and endometrial tumors show the microsatellite instability (MSI) phenotype because of loss of DNA mismatch repair (MMR) function. The incidence of MSI in tumors of the central nervous system still remains controversial. Previous studies reported a particular high frequency of MSI (approximately 25%) in young patients suffering from high-grade gliomas. Based on these data and the fact that in different tumor entities MMR deficiency defines a subgroup of tumors with distinct pathogenesis and particular clinicopathological features that may have impact on prognosis and therapy, we screened 624 gliomas from 71 young and 553 adult patients for MMR deficiency by MSI analysis using three highly sensitive diagnostic markers. Alterations of MMR protein expression was examined by immunohistochemistry. A malignant glioma from an adult patient displayed MSI and concomitant loss of nuclear MSH2 and MSH6 protein expression (0.16%; 1/619). No evidence for MSI or loss of MMR protein expression was observed in 71 gliomas from young patients (0%; 0/71) including 41 high-grade astrocytic tumors. Overall, we observed a much lower incidence of MSI among high-grade pediatric gliomas than initially reported and suggest that MMR deficiency does not play a major role in the pathogenesis of glial neoplasms.     

Low frequency of SV40, JC and BK polyomavirus sequences in human medulloblastomas, meningiomas and ependymomas

Several reports have suggested a role for polyomaviruses in the pathogenesis of human brain tumors. This potential involvement is not conclusively resolved. For the present study, a highly sensitive PCR-assay with fluorescence-labelled primers was developed to search for polyomavirus sequences in human brain tumor and control DNA samples. The assay was shown to detect approximately one viral large T-antigen (TAg) gene per 250 cells. We identified simian virus 40 (SV40)-like sequences in 2/116 medulloblastomas, in 1/131 meningiomas, in 1/25 ependymomas and in 1/2 subependymomas. A single case of ependymoma contained SV40 VP-1 late gene sequences. Moreover, one of the meningioma samples showed JC virus sequences. In contrast, 60 hepatoblastoma samples and 31 brain samples from schizophrenic patients were consistently negative. BK virus sequences were not detectable in any of our samples. Immunohistochemical analysis of two SV40 positive tumor biopsies failed to detect large TAg in the tumor cells. In the JC positive meningioma, immunoreactivity for the viral late gene product (VP-1) was not observed. Our data do not entirely rule out SV40 and JC virus as an initiative agent with a hit-and-run mechanism. However the low frequency of virus sequences and the absence of TAg protein expression argue against a major role of these viruses in the pathogenesis of human medulloblastomas, meningiomas and ependymomas.     

Wertigkeit der radiologischen Bildgebung beim Kniegelenk für den Orthopäden

Extended radiographic examinations offer excellent options for diagnosis and strategy for treatment of the knee joint. The whole-leg radiograph is indispensable in measuring alignment for osteotomy or total knee arthroplasty (TKA). Fluoroscopically assisted varus-valgus stress radiographs provide the possibility for verifying mechanical function of the implanted knee prosthesis. Ultrasound examinations have been widely replaced by magnetic resonance imaging (MRI). MRI is the golden standard to examine intra-articular structures of the knee (meniscus, ligaments, cartilage) and surrounding soft tissue. For evaluating femoral and tibial torsion and determining axial rotation of TKA, computed tomography (CT) is best qualified. Imaging of the patellofemoral joint (patella instability) is difficult; CT scans in combination with true lateral radiographs seem to be helpful.     

Shoulder instability: impact of glenohumeral arthrotomography on treatment

We used arthrotomography to study the glenoid labrum in 114 patients. Sixty-nine of the patients had anatomic instability of the shoulder (including recurrent dislocation and subluxation of the shoulder), and 45 patients had functional instability of the shoulder (denoted by chronic pain, clicking of the joint, and the sensation that an unstable condition exists without the objective signs of it). Labral tears were revealed arthrotomographically in 86% of the patients with anatomic instability, while only 40% of the patients with functional instability had labral abnormalities, and these were primarily of minor severity. Fifty-six patients (44 of whom had anatomic instability; 12, functional instability) required surgery. The surgical findings were correlated with the arthrotomographic findings, and no false-positive results were revealed. However, arthrotomography demonstrated only part of the pathologic condition of two patients. These results confirm that there is a strong correlation between labral pathologic conditions and anatomic instability of the shoulder. Arthrotomographic studies have a great impact on the selection of therapy in cases of both anatomic and functional instability of the shoulder.