Charlotte A. Brown

Genetic alterations in chronic ulcerative colitis-associated adenoma-like DALMs are similar to non-colitic sporadic adenomas.

Recent molecular studies have shown that there are differences in the prevalence and timing of certain molecular events between chronic ulcerative colitis (CUC)-associated dysplastic lesions and non-CUC-related sporadic adenomas. However, little is known regarding the molecular features of a specific subtype of CUC-related dysplasia-associated lesion or mass (DALM) that clinically, endoscopically, and pathologically resemble sporadic adenomas, and whether these lesions can be separated from non-CUC-related sporadic adenomas on the basis of their molecular genotype. Therefore, the purpose of this study was to evaluate loss of heterozygosity (LOH) of 3p, APC, and p16 in a specific group of CUC-associated “adenoma-like” DALMs and to compare the results of this tumor with those in a well-defined group of CUC-associated non-adenoma-like DALMs and non-CUC-associated sporadic adenomas. Polypectomy or resection specimens from 21 CUC patients with an adenoma-like DALM, 8 CUC patients with at least one non-adenoma-like DALM (12 lesions in total), and 23 non-CUC patients with a sporadic adenoma were evaluated for LOH of 3p, APC, and p16 by PCR analysis. The results were compared among the three different study groups and correlated with the clinical features of the patients and the pathology of their tumors. Chronic ulcerative colitis-associated adenoma-like DALMs showed LOH of 3p in five of 18 (28%) cases. This value was not significantly different from the 5% of non-CUC sporadic adenomas (p = 0.14) that were positive. However, 50% of CUC-associated non-adenoma-like DALMs were positive for LOH of 3p, and this value was significantly higher (p = 0.01) than the other groups. The frequency of LOH of APC did not differ significantly between the three patient groups (33%, 33%, and 43% in the three groups, respectively). Similar to the 3p results, CUC-associated adenoma-like DALMs and non-CUC-associated sporadic adenomas showed a similar low frequency of positivity for LOH of p16 (5% and 4%, respectively) in comparison to 56% of CUC-associated non-adenoma-like DALMs (p = 0.003). For all markers, no significant differences were detected in the CUC-associated adenoma-like DALM group between lesions that occurred within colitis compared with those that occurred in areas not involved by colitis. Chronic ulcerative colitis-associated non-adenoma-like DALMs have a different molecular genotype than CUC-related adenoma-like DALMs and non-CUC sporadic adenomas. Our data also suggests that the latter two groups of neoplasms may in fact represent a similar, if not identical, pathogenetic entity.

A Common Polymorphism in Methionine Synthase Reductase Increases Risk of Premature Coronary Artery Disease

Background Methionine synthase reductase (MTRR) catalyzes the regeneration of methylcobalamin, a cofactor of methionine synthase, an enzyme essential for maintaining adequate intracellular pools of methionine and tetrahydrofolate, as well as for maintaining homocysteine concentrations at nontoxic levels. We recently identified a common A → G polymorphism at position 66 of the cDNA sequence of MTRR; this variant was associated with a greater than normal risk for spina bifida in the presence of low levels of cobalamin. Objective To investigate whether the polymorphism was associated with alterations in levels of homocysteine, folate, and vitamin B12, and with risk of developing premature coronary artery disease (CAD), in a population of individuals presenting for cardiac catheterization procedures. Methods We screened 180 individuals aged < 58 years with angiographically documented coronary-artery occlusions or occlusion-free major arteries for the presence of the 66A → G MTRR polymorphism using a polymerase-chain-reaction-based assay. Results We identified a trend in risk of premature CAD across the genotype groups (P =0.03) with a sex-adjusted relative risk of premature CAD equal to 1.49 (95% confidence interval 1.10–2.03) for the GG versus AA genotype groups. There was no difference in fasting levels of plasma total homocysteine, serum folate, and vitamin B12 among the three MTRR genotypes. Conclusions Our findings suggest that the GG genotype of MTRR is a significant risk factor for the development of premature CAD, by a mechanism independent of the detrimental vascular effects of hyperhomocysteinemia. This association needs to be confirmed in other studies.

Distinction between dysplasia-associated lesion or mass (DALM) and adenoma in patients with ulcerative colitis

Polyps with epithelial dysplasia in ulcerative colitis (UC) represent either dysplasia-associated lesions or masses (DALMs) or sporadic adenomas. DALMs are frequently associated with associated carcinoma and are an indication for colectomy. Removal of the polyp is treatment of choice for sporadic adenomas. Differentiating between these 2 lesions is not always easy. The goal of this study was to distinguish DALMs from adenomas in patients with UC on a genetic basis. We evaluated genetic alterations in DALMs and compared them with a previously published set of dysplastic polyps in patients with UC that were considered adenomas for the following reasons: (1) polyps were located outside of current active disease; (2) polyps had histological features of sporadic adenomas; and (3) patients displayed a uneventful follow-up after polypectomy (UC-adenomas). In addition, adenomas not associated with UC were studied. Genetic alterations on chromosome 3p were assessed for the markers D3S1766, D3S2409, and D3S2387. LOH with or without microsatellite instability was found in 70%, 37%, and 57% of cases of DALM, respectively. In contrast, UC-adenomas lesions exhibited genetic alterations in 8.3%, 11.7%, and 15.3% for the respective markers. Spontaneous adenomas exhibited genetic alterations in 10.5%, 7.1%, and 0% of cases, which were not significantly different from the UC-adenoma results. These results indicate that UC-adenomas are genetically and biologically similar to sporadic adenomas and that UC-adenomas may biologically represent sporadic adenomas, supporting on a genetic basis the criteria chosen to diagnose adenomas in UC. Genetic markers on chromosome 3p may be useful in the differential diagnosis between DALM and UC-adenomas.

Novel LMNA Mutations in Patients With Emery-Dreifuss Muscular Dystrophy and Functional Characterization of Four LMNA Mutations

Mutations in LMNA cause a variety of diseases affecting striated muscle including autosomal Emery‐Dreifuss muscular dystrophy (EDMD), LMNA‐associated congenital muscular dystrophy (L‐CMD), and limb‐girdle muscular dystrophy type 1B (LGMD1B). Here, we describe novel and recurrent LMNA mutations identified in 50 patients from the United States and Canada, which is the first report of the distribution of LMNA mutations from a large cohort outside Europe. This augments the number of LMNA mutations known to cause EDMD by 16.5%, equating to an increase of 5.9% in the total known LMNA mutations. Eight patients presented with either p.R249W/Q or p.E358K mutations and an early onset EDMD phenotype: two mutations recently associated with L‐CMD. Importantly, 15 mutations are novel and include eight missense mutations (p.R189P, p.F206L, p.S268P, p.S295P, p.E361K, p.G449D, p.L454P, and p.W467R), three splice site mutations (c.IVS4 + 1G>A, c.IVS6 − 2A>G, and c.IVS8 + 1G>A), one duplication/in frame insertion (p.R190dup), one deletion (p.Q355del), and two silent mutations (p.R119R and p.K270K). Analysis of 4 of our lamin A mutations showed that some caused nuclear deformations and lamin B redistribution in a mutation specific manner. Together, this study significantly augments the number of EDMD patients on the database and describes 15 novel mutations that underlie EDMD, which will contribute to establishing genotype–phenotype correlations. Hum Mutat 31:–16, 2011.

Changes at P183 of emerin weaken its protein-protein interactions resulting in X-linked Emery-Dreifuss muscular dystrophy

Abstract Emery-Dreifuss muscular dystrophy (EDMD) is an X-linked recessive muscular dystrophy characterized by early contractures of the elbows, Achilles tendons and spine, slowly progressive muscle wasting and weakness, and cardiomyopathy associated with cardiac conduction defects. The emerin gene has been mapped to Xq28 and encodes a 34-kDa serine-rich protein, emerin, which has been localized to the nuclear envelope in a wide variety of tissues, including skeletal and cardiac muscle. Mutations spanning the emerin gene have been identified in patients with EDMD. We present here the effect, on emerin protein expression, of two missense mutations identified in unrelated EDMD patients. These alterations predict the replacement of a proline residue at position 183 with either a histidine or a threonine. Biochemical analysis has demonstrated that the mobility and expression levels of the mutant forms of emerin are indistinguishable from that of wild-type emerin, but that they have weakened interactions with nuclear lamina components. In comparison with the usual EDMD phenotype, patients with P183 missense mutations have a later age at onset of first symptoms, elbow contractures, ankle contractures, upper limb weakness and lower limb weakness, but there is no difference for the age at onset of cardiac involvement. This is the first report of protein studies on patients with missense mutations resulting in the clinical features of EDMD. These studies demonstrate the importance of proline 183 for the proper structure/function of emerin.

Molecular alterations in chronic ulcerative colitis-associated and sporadic hyperplastic polyps: a comparative analysis

OBJECTIVES:There is growing interest in the biological and molecular features and neoplastic potential of colonic hyperplastic polyps because of the recent finding of K-ras mutations in many of these lesions. Hyperplastic polyps may also develop in chronic ulcerative colitis (CUC), but it is unclear if these are biologically similar to the sporadic type. The aim of this study was to evaluate and compare the molecular profile of CUC-associated hyperplastic polyps with sporadic hyperplastic polyps of the colon.METHODS:Thirty-nine hyperplastic polyps from 26 CUC patients, 39 sporadic hyperplastic polyps from 29 age- and sex-matched patients without CUC, and 26 colonic mucosal biopsies from 22 patients with CUC but without hyperplastic polyps were analyzed by polymerase chain reaction for loss of heterozygosity of APC, 3p, p53, and p16 and for mutations in codons 12, 13, and 61 of the K-ras gene. Immunohistochemical evaluations for the proliferation-associated nuclear peptide Ki67 (MIB-1) and p27 were also performed on a subset of hyperplastic polyps.RESULTS:CUC-associated hyperplastic polyps showed a proportion of genetic alterations (47%) similar to that of sporadic hyperplastic polyps (33%) (p > 0.05), and neither significantly differed from chronically inflamed mucosae in CUC patients without hyperplastic polyps. Furthermore, in a small group of CUC patients in which informative tissue was available from both their hyperplastic polyps and adjacent flat colitic mucosae, the polyps contained mutations that were not present in the underlying mucosa. Loss of heterozygosity of APC, 3p, p53, p16, and K-ras mutations were present in 21%, 40%, 27%, 20%, and 19% of CUC patients with hyperplastic polyps, respectively, and in 0%, 11%, 20%, 13%, and 13% of non-CUC patients with sporadic polyps, respectively. Both CUC-associated and sporadic hyperplastic polyps showed a substantial number of cases (46% and 64% of cases, respectively) with loss of p27 expression, and both types of lesions showed similar MIB-1 proliferation indices.CONCLUSIONS:These data suggest that CUC-associated hyperplastic polyps are genotypically similar to the sporadic type. This study adds to the expanding list of molecular alterations that have been discovered in hyperplastic polyps, and lends further support to the controversial theory that these lesions may have neoplastic potential.

Tissue-specific methylation differences and cognitive function in fragile X premutation females.

Tissue-specific variation in (CGG)n repeat size and methylation status of the FMR1 gene was investigated in 17 female premutation carriers. Minor variation in premutation repeat size among leukocyte, lymphoblast, and fibroblast tissues was noted in some subjects. One subject exhibited a premutation size allele of (CGG)64 in leukocyte and fibroblast tissues by polymerase chain reaction analysis but a normal-size allele of (CGG)46 in lymphoblast cells, suggesting low-level mosaicism in blood and clonality of the lymphoblast cell line. Six subjects exhibited differences in methylation pattern between leukocytes and lymphoblasts but not between leukocytes and fibroblasts, whereas 2 subjects showed large differences in methylation pattern between leukocytes and fibroblasts. Cognitive function was studied in 14 subjects using the Wechsler Adult Intelligence Scale-Revised. Mean Verbal and Performance IQs were well within the average range as was the mean Full Scale IQ; nevertheless, a trend toward lower Performance IQ compared with Verbal IQ was observed. No significant correlation was apparent between Full Scale IQ and (CGG)n repeat size; however, a significant positive correlation was observed between Full Scale IQ and the proportion of the active X carrying the normal FMR1 allele in fibroblasts but not in leukocytes or lymphoblasts.

Primary Endometrial T-Cell Lymphoma A Case Report

Primary lymphomas of the female genital tract are rare. Most involve the cervix rather than the uterine corpus. All of those previously reported have been B-cell lymphomas, with the exception of 1 case report of an endometrial T-cell lymphoma in a Japanese woman. We report the case of a white woman from the United States with a diffuse large cell lymphoma of the endometrium, characterized as a peripheral T-cell type on the basis of immunophenotypic and molecular probe studies. Staging evaluation revealed tumor limited to the endometrium (stage IE). The patient underwent a total abdominal hysterectomy, bilateral salpingo-oophorectomy, and lymph node dissection and received 6 cycles of combination chemotherapy, after which she remained free of disease at last follow-up of 36 months. Unusual features of this lymphoma case are discussed, with emphasis on differential diagnosis and speculation on histogenesis. This case illustrates that, while most peripheral T-cell lymphomas are widely disseminated at presentation, those limited to a single extranodal site may have a favorable outcome akin to that associated with high-grade extranodal B-cell lymphomas of early stage.

Two distal mutations in the gene encoding emerin have profoundly different effects on emerin protein expression.

Emerin, the product of the gene responsible for X-linked Emery-Dreifuss muscular dystrophy (EDMD), has a ubiquitous tissue distribution and is localised to the nuclear envelope. We present here the relationship between emerin protein expression, nuclear localization and clinical phenotype for two distal mutations identified in unrelated EDMD patients. The first mutation predicts the replacement of the last eight amino acids of emerin with the addition of 101 amino acids, but no emerin expression is detected. The second mutation, 35 bp upstream from the first mutation, deletes six amino acids from the transmembrane region, but in this case emerin expression is seen. Emerin from this second patient is expressed at reduced levels, mistargeted and has altered biochemical properties compared to wild type emerin. In both cases the clinical phenotype was similar to patients with typical null mutations. We discuss these data in comparison with previous reports of other C-terminal mutations in the emerin gene and suggest that the efficiency of emerins nuclear membrane localization is affected by the hydrophobicity (and possibly length) of its transmembrane region, and a longer C-terminal tail prevents nuclear localization.

Novel and recurrent EMD mutations in patients with Emery–Dreifuss muscular dystrophy, identify exon 2 as a mutation hot spot

Emery–Dreifuss muscular dystrophy (EDMD) is a neuromuscular disorder exhibiting a cardiomyopathy with cardiac conduction defects. X-linked EDMD arises from mutations in the EMD gene, which encodes for a nuclear membrane protein termed emerin. In this study, we describe novel and recurrent EMD mutations identified in 18 probands and three carriers from a cohort of 255 North American patients referred for EDMD genetic mutation analysis. Eight of these mutations are novel including six frameshift mutations (p.D9GfsX24, p.F39SfsX17, p.R45KfsX16, p.F190YfsX19, p.R203PfsX34 and p.R204PfsX7) and two non-sense mutations (p.S143X, p.W200X). Our data augment the number of EMD mutations by 13.8%, equating to an increase of 5.2% in the total known EMD mutations and to an increase of 6.0% in the number of different mutations. Analysis of the exon distribution of mutations within the EMD gene, suggests a nonrandom distribution, with exon 2 as a hot spot. This phenomenon may be due to its high GC content, which at 60% is the most GC-rich exon in the EMD gene.