Clinical and molecular characterization of 40 patients with Noonan syndrome

Noonan syndrome (NS, OMIM 163950) is an autosomal dominant disorder, with a prevalence at birth of 1:1000–1:2500 live births, characterized by short stature, facial and skeletal dysmorphisms, cardiovascular defects and haematological anomalies. Missense mutations of PTPN11 gene account for approximately 50% of NS cases, while molecular lesions of other genes of the RAS/MAPK pathway – KRAS, SOS1 and RAF1 – play a minor role in the molecular pathogenesis of the disease. Forty patients were enrolled in the study with a PTPN11 mutation detection rate of 31.5%, including a novel missense mutation, Phe285Ile, in a familial case with high intrafamilial phenotypic variability. All patients negative for PTPN11 mutations were further screened for mutations of the KRAS, SOS1, and RAF1 genes, revealing a Thr266Lys substitution in SOS1 in a single patient, a newborn with a subtle phenotype, characterized by facial dysmorphisms and a mild pulmonic stenosis.     

Mapping of MRX81 in Xp11.2-Xq12 suggests the presence of a new gene involved in nonspecific X-linked mental retardation

X-linked nonspecific mental retardation (MRX) accounts for approximately 25% of mental retardation in males. A number of MRX loci have been mapped on the X chromosome, reflecting the complexity of gene action in central nervous system (CNS) specification and function. Eleven MRX genes have been identified, but many other causative loci remain to be refined to the single gene level. In 21 MRX families, the causative gene is located in the pericentromeric region; and we report here the identification by linkage analysis of a further such locus, MRX81. The new MRX locus was identified by two- and multi-point parametric analysis carried out on a large Italian family. Tight linkage of MRX81 to DNA markers ALAS2, DXS991, and DXS7132 was observed with a maximum LOD score of 3.43. Haplotype construction delineates an MRX81 critical region of 8 cM, the smallest MRX pericentromeric interval so far described, between DXS1039 and DXS1216, and placing it in Xp11.2-Xq12. So far, automated sequencing of two candidates in the region, the MRX gene oligophrenin (OPHN1) and the brain-specific ephrinB1 (EFNB1) gene, in DNA from affected males excluded their candidacy for MRX81, suggesting a novel disease gene.     

HLA-C1 ligands are associated with increased susceptibility to systemic lupus erythematosus

Recently, the role of killer cell immunoglobulin-like receptor (KIR) in autoimmune diseases has received increasing attention. The present study was undertaken to determine the association of KIR genes and the human leukocytes antigen (HLA) ligands with Systemic Lupus Erythematosus (SLE) and accompanying oxidative stress. Presence or absence of 17 KIR and 5 HLA loci was performed using the polymerase chain reaction-sequence specific primer (PCR-SSP) method by case-control study. A total of 45 SLE patients, and 60 healthy controls, all of Sicilian descent, were enrolled. Plasma values of the anti-oxidant molecule Taurine were determined in all subjects by capillary electrophoresis UV detection. The carrier frequency of the KIR2DS2 gene was significantly increased in SLE patients compared to healthy controls (73.3 versus 45.0%; OR?=?3.36; 95% CI?=?1.46–7.74; p?=?.005) suggesting a role of KIR2DS2 gene in the susceptibility to disease. We also observed a strong positive association between the presence of HLA-C1 ligands group and the disease (82.2% in SLE patients versus 41.7% in controls; OR?=?6.47, 95% CI?=?2.58–16.26; p?<?.0001). Stepwise logistic regression analysis supported the effect of the HLA-C1 ligands in SLE patients (OR?=?7.06, 95% CI?=?0.07–2.19; p?=?.002), while the KIR genes were no longer significant. Interestingly, we found that SLE patients HLA-C1 positive showed significantly decreased plasma levels of antioxidant activity marker Taurine (69.38?±?28.49?μmol/L) compared to SLE patients HLA-C1 negative (108.37?±?86.09?μmol/L) (p?=?.03). In conclusion, HLA-C1 ligands group was significantly associated with an increased risk of SLE as well as an increased oxidative stress status overall in SLE patients.     

Direct acute tubular damage contributes to Shigatoxin‐mediated kidney failure

The pathogenesis and therapy of Shigatoxin 2 (Stx2)‐mediated kidney failure remain controversial. Our aim was to test whether, during an infection with Stx2‐producing E. coli (STEC), Stx2 exerts direct effects on renal tubular epithelium and thereby possibly contributes to acute renal failure. Mice represent a suitable model because they, like humans, express the Stx2‐receptor Gb3 in the tubular epithelium but, in contrast to humans, not in glomerular endothelia, and are thus free of glomerular thrombotic microangiopathy (TMA). In wild‐type mice, Stx2 caused acute tubular dysfunction with consequent electrolyte disturbance, which was most likely the cause of death. Tubule‐specific depletion of Gb3 protected the mice from acute renal failure. In vitro, Stx2 induced secretion of proinflammatory cytokines and apoptosis in human tubular epithelial cells, thus implicating a direct effect of Stx2 on the tubular epithelium. To correlate these results to human disease, kidney biopsies and outcome were analysed in patients with Stx2‐associated kidney failure (n = 11, aged 22–44 years). The majority of kidney biopsies showed different stages of an ongoing TMA; however, no glomerular complement activation could be demonstrated. All biopsies, including those without TMA, showed severe acute tubular damage. Due to these findings, patients were treated with supportive therapy without complement‐inhibiting antibodies (eculizumab) or immunoadsorption. Despite the severity of the initial disease [creatinine 6.34 (1.31–17.60) mg/dl, lactate dehydrogenase 1944 (753–2792) U/l, platelets 33 (19–124)/nl and haemoglobin 6.2 (5.2–7.8) g/dl; median (range)], all patients were discharged after 33 (range 19–43) days with no neurological symptoms and no dialysis requirement [creatinine 1.39 (range 0.84–2.86) mg/dl]. The creatinine decreased further to 0.90 (range 0.66–1.27) mg/dl after 24 months. Based on these data, one may surmise that acute tubular damage represents a separate pathophysiological mechanism, importantly contributing to Stx2‐mediated acute kidney failure. Specifically in young adults, an excellent outcome can be achieved by supportive therapy only. © 2014 The Authors. The Journal of Pathology published by John Wiley & Sons Ltd on behalf of Pathological Society of Great Britain and Ireland.     

Endogenous levels of mRNA for IFNs and IFN-related genes in hepatic biopsies of chronic HCV-infected and non-alcoholic steatohepatitis patients

To investigate the intra-hepatic activation of the IFN system in patients affected by chronic HCV-infection in comparison with that observed in a non-infectious liver disease such as non-alcoholic steatohepatitis, we measured the liver steady state mRNA levels of interferon-alpha, interferon-beta and interferon-gamma as well as of IFN-related genes (IFNAR-1, STAT1alpha, PKR, 2-5 AS, IRF-1, ICE and IL-18). In HCV-infected subjects, possible correlations of these parameters with viral load and liver injury were also analyzed. Twenty-four chronic untreated HCV-infected subjects and seven patients with non-alcoholic steatohepatitis were enrolled in the study. Liver biopsies were graded according to Knodell scores. Intra-hepatic mRNA levels of IFNs and related genes were assessed by semi-quantitative RT-PCR. In comparison with non-alcoholic steatohepatitis, in HCV-infected subjects IFN-alpha and -beta mRNA levels were significantly lower, whereas IFN-gamma, IFNAR-1, STAT1alpha IRF-1, and IL-18 mRNA were upregulated. Moreover, IFN-gamma mRNA steady state levels were correlated positively with those of IFNAR-1, IRF-1, and IL-18, suggesting a coordinated induction of these genes. Although plasma viral load was correlated inversely with IL-18-specific mRNA, viral load was not related to liver injury. IFN-gamma and IRF-1 mRNA levels were correlated positively with ALT, but not with the grading or staging. Conversely, IFN-alpha and -beta mRNA levels were higher in livers with lower staging scores. These findings support the hypothesis that in chronic HCV infection there is an imbalance between an upregulated IFN-gamma system and a downregulated IFN-alpha and -beta system, probably due to a mixed effect exerted by HCV-specific and inflammatory non-specific factors.     

Typing of human papillomavirus in women with cervical lesions: Prevalence and distribution of different genotypes

Human papillomavirus (HPV) are distributed widely and persistent infection with high‐risk (HR) HPV is recognized as a necessary cause of cervical cancer. The aim of this study was to evaluate the distribution of different HR‐HPV genotypes in 199 women with cervical pre‐invasive lesions undergoing conservative treatment. A Linear Array HPV Genotyping Test was used to identify individual HPV genotypes in cervical samples. It was observed that the most prevalent HPV genotypes were HPV 16 (52.6%), HPV 51 (13.5%), and HPV 31 (10.9%); HPV 18 was found in 7.3% of the patients. Stratifying the different HPV genotypes according to the severity of the cervical lesion, a strong association between the increasing severity of the histological diagnosis and the detection of more carcinogenic HR‐HPV type was found, and in all but one cervical intraepithelial neoplasia of grade 3 the presence of at least one HR‐HPV could be detected, with more than 70% of cervical intraepithelial neoplasia of grade 3 patients bearing HPV 16. Multiple infections, comprising between 2 and 6 HPV types, were found in 43% of patients; however, the presence of more than 1 HR‐HPV type was not associated with an increased risk of high grade lesions. In conclusion, this data show that HPV 16, 51, 31, 52, and 18 were the prevalent types found in patients with cervical lesion undergoing conservative treatment, with a high prevalence of HPV 16 in cervical intraepithelial neoplasia of grade 3 patients. No association between multiple infection and severity of the lesion could be found. J. Med. Virol. 81:271–277, 2009. © 2008 Wiley‐Liss, Inc.     

HLA DR13 and HCV vertical infection

Risk factors affecting vertical hepatitis C virus (HCV) transmission are not completely known, if we exclude maternal HIV coinfection. We hypothesized that immunogenetic factors related to maternal or neonatal HLA profiles may affect HCV vertical transmission. HLA typing (microcytotoxicity assay on blood samples) was performed in 18 infants affected by vertically transmitted HCV infection and in 17 serum-reverted infants. (Serum-reversion is defined as antibody negative by 1 year of age and persistently HCV-RNA negative.) Moreover, HLA typing was performed in 20 mothers. Logistic regression analysis showed a significant negative association between children's HLA-DR13 antigens and risk of HCV vertical transmission (p < 0.01). This association persisted in a model including the maternal HIV status: HLA DR13 and maternal HIV coinfection showed a separate, opposite effect on vertical HCV infection (p < 0.01 and p < 0.001, respectively). The relative risk estimate for the ratio of not-infected to infected children in the presence of DR13 was 8.4 (95% confidence bounds, 1.1-60.8). Breast-feeding did not affect the risk of vertical HCV transmission. Maternal HLA profile did not relate to vertical infection. The present study reveals a significant association between HLA-DR13 and the likelihood of seroreversion in infants born to HCV-infected mothers. The findings of the present study could help in better understanding the pathogenesis of vertical HCV infection and in better identifying the cases at higher risk, which would be useful for the development of prevention strategies. It is possible that DR13 modulates the immune response to viruses, enhancing their clearance and, thus, in the case of HCV, exerting a protective role against the development of vertical infection.