Marfan syndrome: exclusion of genetic linkage to the COL1A2 gene

Marfan Syndrome is a genetic disorder of the connective tissue. Individuals from one large family with this disorder were genotyped for COL1A2 gene associated RFLPs. Our results demonstrated that the COL1A2 gene, encoding the proa2(I) collagen chain, segregated independently of the phenotype and it is therefore excluded as the mutant locus in this family.     

Effects of age, sex and genes on sister chromatid exchange

Sister chromatid exchange (SCE) was studied in cultured lymphocytes from a limited series of 21 like-sexed twin pairs; 11 monozygotic (MZ) and 10 dizygotic (DZ) pairs. The 18 subjects, who were between 57 and 61 years old, had an SCE mean value () of 8.0 whereas the 24 subjects between 33 and 39 years of age had a mean of 6.8. The difference was statistically significant ( P <0.001). The effect of age appeared to be present in both sexes. No significant difference was found between females (%7.3) and males (%7.5), nor between smokers (%7.3) and non-smokers (%7.4). Drug users had a slightly higher mean (%7.9) than non-users (= 7.0) ( P < 0.05). This trend was found in each age group. The within-pair variance was slightly higher in DZ than in MZ pairs. The difference was not significant. We conclude that genetic factors are probably not a major source of subject variation in SCE mean value.     

Increased yield of full GBA sequencing in Ashkenazi Jews with Parkinson's disease

Background

Variants in GBA are the most common genetic risk factor for Parkinson's disease (PD), and are especially prevalent in the Ashkenazi Jewish (AJ) population. However, most studies on GBA in AJ genotype only seven selected Gaucher-associated pathogenic variants rather than sequencing the whole gene, which may leave carriers of PD-associated GBA variants undiscovered.

Whole-exome sequencing of Finnish patients with vascular cognitive impairment

Cerebral small vessel disease (CSVD) is the most important cause of vascular cognitive impairment (VCI). Most CSVD cases are sporadic but familial monogenic forms of the disorder have also been described. Despite the variants identified, many CSVD cases remain unexplained genetically. We used whole-exome sequencing in an attempt to identify novel gene variants underlying CSVD. A cohort of 35 Finnish patients with suspected CSVD was analyzed. Patients were screened negative for the most common variants affecting function in NOTCH3 in Finland (p.Arg133Cys and p.Arg182Cys). Whole-exome sequencing was performed to search for a genetic cause of CSVD. Our study resulted in the detection of possibly pathogenic variants or variants of unknown significance in genes known to associate with CSVD in six patients, accounting for 17% of cases. Those genes included NOTCH3, HTRA1, COL4A1, and COL4A2. We also identified variants with predicted pathogenic effect in genes associated with other neurological or stroke-related conditions in seven patients, accounting for 20% of cases. This study supports pathogenic roles of variants in COL4A1, COL4A2, and HTRA1 in CSVD and VCI. Our results also suggest that vascular pathogenic mechanisms are linked to neurodegenerative conditions and provide novel insights into the molecular basis of VCI.Subject terms: Stroke, Sequencing, Genetics research, Dementia     

Mapping of B-Cell Epitopes in a Trypanosoma cruzi Immunodominant Antigen Expressed in Natural Infections

Tc40 is an immunodominant antigen present in natural Trypanosoma cruzi infections. This immunogen was thoroughly mapped by using overlapping amino acid sequences identified by gene cloning and chemical peptide synthesis. To map continuous epitopes of the Tc40 antigen, an epitope expression library was constructed and screened with sera from human chagasic patients. A major, linear B-cell epitope spanning residues 403 to 426 (PAKAAAPPAA) was identified in the central domain of Tc40. A synthetic peptide spanning this region reacted strongly with 89.8% of the serum samples from T. cruzi-infected individuals. This indicates that the main antigenic site is defined by the linear sequence of the peptide rather than a conformation-dependent structure. The major B-cell epitope of Tc40 shares a high degree of sequence identity with T. cruzi ribosomal and RNA binding proteins, suggesting the existence of cross-reactivity among these molecules.     

Up-regulated expression of HGF in rat liver cells after experimental endotoxemia: a potential pathway for enhancement of liver regeneration

A lipopolysaccharide (LPS)-induced inflammation prior to an hepatic resection has been shown to enhance liver regeneration in rat. The aim of the present study was to investigate the expression of hepatocyte growth factor (HGF) and its c-Met receptor under such experimental conditions. Animals were submitted to a two-third hepatectomy or a LPS challenge carried out 12 h prior to resection. Non parenchymal and parenchymal cells were isolated from livers obtained at various times post-hepatectomy. Quantitative RT-PCR for HGF and c-Met mRNAs were performed from total liver or purified cell fractions and HGF mRNA was also analyzed by in situ RT-PCR on liver sections. A LPS challenge alone induced a marked up-regulation of HGF mRNA level in whole liver and isolated hepatocytes. Furthermore, when partial hepatectomy (PH) was preceded by a LPS challenge, an increase of HGF mRNA level was seen in whole liver and contrasted with a decreased level in non parenchymal cells. These results were confirmed by in situ RT-PCR. In isolated hepatocytes from endotoxemic rats, the mRNA level for the LPS-specific membranous receptor mCD14 was markedly up-regulated and even more so when LPS was followed by PH. Moreover, a TNFalpha challenge alone induced an up-regulation of HGF mRNA in hepatocytes and a down-regulation in non parenchymal cells (NPCs). Overall, when a LPS challenge is given prior to PH the major source of hepatic HGF appears to be the hepatocyte itself rather than NPCs. An autocrine HGF/c-Met loop which promotes the proliferative potential of the hepatic parenchymal cell and participates in liver regeneration is postulated.     

Study of neu-protein expression in mammary Paget's disease with and without underlying breast carcinoma and in extramammary Paget's disease.

Correlation between neu/c-erbB-2/Her-2 gene amplification and overexpression of the neu gene product has been reported in tumors of glandular origin, especially ductal breast carcinomas. Formalin-fixed and dewaxed sections from 23 cases of mammary (MPD) and 9 cases of extramammary (EPD) Paget's disease were immunohistochemically stained by means of the monoclonal antibody 3B5 directed against an intracellular domain of the neu gene protein. All MPDs exhibited a distinct membrane staining of tumor cells independent of the presence of ductal breast carcinomas found in 18 cases. All these breast carcinomas also were positive for neu staining. In contrast to MPD, all EPDs were negative. Normal epidermis was always negative. Northern blot analysis sustained the immunohistologic findings in that the presence of neu mRNA could be demonstrated in two of three cases with MPD. Negativity in one case was due to dilution effects by nontumor cells. Our results suggest that Paget cells of mammary and extramammary localization, although very similar phenotypically, derive from different genetic accidents. Furthermore neu positivity in all MPDs and all underlying ductal carcinomas suggests common genetic alterations for both tumors. However the finding of five neu protein-positive MPDs without associated ductal breast carcinomas may suggest a somewhat different transformation process.     

Mycobacterium simiae infections: about two cases

We report two cases of Mycobacterium simiae infections differing by the site of infection, the immunological status of the patients and the diagnostic methods used. The first case is a disseminated infection in an advanced immunosuppressed patient who died quickly confirming the severity of this infection in the context of HIV infection. The second case presented is a respiratory disease in a women with a past history of tuberculosis and an uneventful evolution of the M. simiae infection under treatment. These two cases demontrate the importance of molecular methods to correctly identify M. simiae.     

Sarcomatoid carcinoma of small intestine: diagnostic problems raised by an unusual tumor

Sarcomatoid carcinomas involving the intestinal tract are rare and usually associated with poor prognosis. We report a case of sarcomatoid carcinoma of the ileum, diagnosed in a 61-year-old man. The patient presented with acute intestinal occlusion. Surgical resection of the ileum was performed. At macroscopic examination, two large polypoid masses were found. Frozen section examination suggested the diagnosis of malignant stromal tumor. At histological examination, both tumors were formed by pleiomorphic, large spindle cells, presenting numerous mitoses and marked nuclear atypia. Immunohistochemical examination showed that tumor cells coexpressed vimentin and epithelial markers (cytokeratins, EMA). The final diagnosis was monomorphic sarcomatoid carcinoma. The patient deceased with metastatic disease after 3 months of follow-up. This report underlines the potential diagnostic problems raised by this unusual type of carcinoma and emphasizes the role of immunohistochemistry in assessing the correct diagnosis.