Association of a novel frameshift variant and a known deleterious variant in MMR genes with Lynch syndrome in Chinese families.

BACKGROUND: Lynch syndrome (LS) is the most common hereditary colorectal cancer (CRC) syndrome. This condition is characterized by germline variants in DNA mismatch repair (MMR) genes, including MLH1, MSH2, MSH6, and PMS2. In this study, we analyzed the molecular defects and clinical manifestations of two families affected with CRC and proposed appropriate individual preventive strategies for all carriers of the variant. METHODS: We recruited two families diagnosed with CRC and combined their family history and immunohistochemical results to analyze the variants of probands and those of other family members by using whole exome sequencing. Subsequently, gene variants in each family were screened by comparing them with the variants available in the public database. Sanger sequencing was performed to verify the variant sites. An online platform ( https://www.uniprot.org ) was used to analyze the functional domains of mutant proteins. RESULTS: A novel frameshift variant (NM_001281492, c.1129_1130del, p.R377fs) in MSH6 and a known deleterious variant (NM_000249.4:c.1731G > A, p.S577S) in MLH1 were identified in the two families with CRC. Using bioinformatics tools, we noted that the frameshift variant reduced the number of amino acids in the MSH6 protein from 1230 to 383, thereby leading to no MSH6 protein expression. The silent variant caused splicing defects and was strongly associated with LS. 5-Fluorouracil-based adjuvant chemotherapy is not recommended for patients with LS. CONCLUSIONS: The novel frameshift variant (MSH6, c.1129_1130del, p.R377fs) is likely pathogenic to LS, and the variant (MLH1, c.1731G > A, p.S577S) has been further confirmed to be pathogenic to LS. Our findings underscore the significance of genetic testing for LS and recommend that genetic consultation and regular follow-ups be conducted to guide individualized treatment for cancer-afflicted families, especially those with a deficiency in MMR expression.

A Novel Splice-Site Mutation in MSH2 Is Associated With the Development of Lynch Syndrome.

Lynch syndrome (LS) is an inherited autosomal dominant disorder caused by germline mutations of mismatch repair (MMR) genes, including MSH2, MSH6, PMS2, and MLH1. This study aimed to analyze the molecular defects and clinical manifestations of an affected family and propose appropriate individual prevention strategies for all mutation carriers. A novel splicing mutation (c.1661+2 T>G) was identified in the MSH2 gene, which was found to co-segregate among affected family members by Whole exome sequencing (WES). RT-PCR analysis confirmed that c.1661+2 T>G could produce 3 transcripts, including 1 normal transcript and 2 aberrant transcripts. The 2 aberrant transcripts resulted in premature termination at the 6th nucleotide codon of MSH2 exon 11, so that the predicted products of the mutant MSH2 mRNAs were truncated proteins of 505 amino acids (with all of exon 10 deleted) and 528 amino acids (with a deletion of 82-nucleotides in exon 10), resulting in the loss of the interaction domain, the ATP domain and post-translationally modified residues. Quantitative RT-PCR (qRT-PCR) analysis showed that MSH2 mRNA levels in all patients were reduced to only 1/4 of the control levels. Our study reveals that a novel splicing mutation (c.1661+2 T>G) in the MSH2 gene causes LS and reaffirms the importance of genetic testing for LS.

Expanded Paramedian Forehead Flaps for Nasal Defects: Beyond Aesthetic Subunits.

BACKGROUND: Reconstruction of nasal tip defects presents a significant challenge for plastic surgeons. The form, function, and aesthetic appeal of all nasal subunits must be addressed. The expanded paramedian forehead flap is a good choice for nasal reconstruction, providing similar texture, structure, and skin color, and high reliability. This article discusses the authors' modification of the expanded paramedian forehead flap in reconstructing defects on or around the nasal tip. METHODS: Twenty-two patients with nasal defects located on or around the nasal tip were treated in our institution. Sixteen patients underwent nasal reconstruction with expanded forehead flaps. The other 6 cases with cartilage defect underwent reconstruction with expanded forehead flaps and autogenous rib cartilage grafts. Functional and cosmetic results were assessed by surgeon, patient, and patient's relatives using a scale from 1 to 10. RESULTS: The aesthetic appearance of all patients was significantly improved after surgery. Two cases had mild hyperpigmentation. Two patients considered the flaps too thick. Three cases had minor brow elevation at the donor site. There were no obvious scars at the donor sites. There were no serious complications, such as infection, flap necrosis, deviation, or collapse. CONCLUSIONS: The expanded paramedian forehead flap is a safe and effective method for reconstructing defects located on or around the nasal tip. Moreover, this technique can result in good functional and cosmetic outcomes with very few complications.

Angiocentric glioma: a report of nine new cases, including four with atypical histological features.

AIMS: Angiocentric glioma (AG) is a rare, slow-growing tumour of the central nervous system. It is often associated with refractory epilepsy and occurs most commonly in children and young adults. We herein report nine cases of AG, including four with atypical histological findings. METHODS: The clinical data and clinicopathological findings of nine cases with AG histological features were described. RESULTS: All nine patients had a history of refractory epilepsy with a mean history of 4.4 years and a median age of 17.6 years at surgery. The AG lesions were located in the superficial cerebrocortical region. Histological examination of these cases revealed characteristic structural features of AG, including bipolar spindle-shaped cells with an angiocentric growth pattern. However, four cases also exhibited atypical histological features: one had astroblastoma-like characteristics, two had a distinct cystic region with an onion-like structure and myxoid changes, and the other one had a region involving many abnormal neurones reminiscent to ganglioglioma. All were positive for glial fibrillary acidic protein and vimentin. Eight cases were positive for epithelial membrane antigen (EMA), with a dot-like staining pattern. A diffuse D2-40 staining was visible in these cases, with two having similar staining pattern to EMA. All cases were immunonegative for BRAF V600E and isocitrate dehydrogenase-1 R132H mutations. CONCLUSIONS: Our results demonstrate that atypical histological features can be present in AG. A collection of more cases and further molecular analyses are required to confirm our findings.

Chordoid glioma of the third ventricle: four cases including one case with papillary features.

Chordoid glioma is a rare, slowly growing tumor of the CNS, which is always located in the third ventricle of adults. Chordoid glioma has classic histological features consisting of clusters and cords of epithelioid tumor cells embedded within a mucinous stroma with rich lymphoplasmacytic infiltrate. The important distinctive immunohistochemical feature of this neoplasm is strong and diffuse reactivity for GFAP. Here, we report four cases of chordoid glioma that occupied the anterior portion of the third ventricle or suprasellar region. These four cases were all adult females with almost typical clinical, radiological, histologic and immunohistochemical characteristics of chordoid glioma. However, in one case there was an unusual histologic finding with regard to the papillary region. In this region, elongated tumor cells were observed radiating toward a central vessel to form characteristic papillary structures. Immunohistochemically, three cases showed strong reactivity for GFAP, and one exhibited weak reactivity. All cases were focally positive for epithelial membrane antigen, CD34 and D2-40, but negative for neurofilament protein (NFP). Several ultrastructural investigations have supported the ependymal origin of chordoid glioma. In some cases of immunoreactivity for NFP, some authors have supposed that chordoid glioma originates from a multipotential stem cell with glial and neuronal cell differentiation. With regard to the present four cases with immunoreactivity for D2-40 (an ependymal marker) and CD34 (undifferentiated neural precursors) and based on previously published data, we considered that the majority of chordoid gliomas had an ependymal origin, and that a small minority might have originated from a multipotential stem cell having ependymal and neuronal cell differentiation.

[Expression of PI3K pathway proteins in refractory epilepsy associated with cortical malformation development].

OBJECTIVE: To investigate the expression of TSC1, TSC2, p-mTOR, p-4E-BP1, p-p70S6K and p-S6 in refractory epilepsy associated malformation of cortical development (MCD) tissues. METHODS: A total of 43 cases of refractory epilepsy were involved in the study, and all the patients were treated in Xuanwu Hospital during 2005 - 2008, including focal cortical dysplasia type IIa (11 cases) and type IIb (11 cases), tuberous sclerosis complex (10 cases) and ganalioglioma (11 cases), and other 12 cases were used as control. These cases were divided into 7 study groups and immunohistochemical EnVision method was used. To detect the location and intensity of TSC1, TSC2, p-mTOR, p-4E-BP1, p-p70S6K and p-S6 expression in every group. Then the Image-Pro Plus 6.0 image processing and analysis software were used to measure the number, area, integrating absorbance (IA) of positive cells in every samples. The statistical software SPSS 16.0 was used to analyze the data. RESULTS: The immunolocalization of TSC1 and TSC2 was similar. It could be observed the expression of various levels in the cytoplasm of dysmorphic neurons, balloon cells, giant cells, ganglioglioma cells and normal neurons. TSC1 staining in normal neurons was more notably than others but TSC2 staining in giant cells was weaker than other samples. p-mTOR mainly presented in giant cells, which could also be observed in astrocyte. P-4E-BP1 presented in the cytoplasm and nuclear membrane of balloon cells, giant cells and ganglioglioma cells, the staining of giant cells was stronger than balloon cells, but their staining were weaker than ganglioglioma cells. P-p70S6K mainly expressed in giant cells and less commonly presented in balloon cells. P-S6 typically presented in all abnormal glioneuronal cells and it nearly did not present in the normal neurons of N-CTX group. CONCLUSIONS: PI3K pathway, at least in part, involves in the occurrence of MCD, and may play an important role in the pathogenesis.