X Mutations (x + mutation)

Distribution by Scientific Domains

Selected Abstracts

Commonalities in the neurobiology between autism and fragile X

R. Hagerman
There is a close association between autism and fragile X syndrome (FXS) with 30% of males with FXS having autism and 2 to 7% of children with autism having the fragile X mutation. The protein that is missing or deficient in FXS, FMRP, is an RNA binding and transport protein which regulates the translation of many messages important for synaptic plasticity. Typically FMRP inhibits the translation of these messages, such that protein production increases when FMRP is absent. Some of these proteins are known to also cause autism when they are mutated including neuroligin 3 and 4 and the SHANK protein. Therefore, when FMRP is missing there is dysregulation of other proteins that are known to cause autism. FMRP is an important inhibitor of protein production in the metabotropic glutamate receptor 5 pathway (mGluR5) which leads to long term depression (LTD) or the weakening of synaptic connections. Therefore, when FMRP is missing there is enhanced mGluR5 activity leading to enhanced LTD and weak or immature synaptic connections. The use of mGluR5 antagonists to reverse the LTD in the animal models of FXS has led to reversal of the learning, behaviour and dendritic spine abnormalities in these animals. There are now initial studies taking place in humans regarding the use of mGluR5 antagonists to improve behaviour and cognition in FXS. It is likely that these mGluR5 antagonists will also be helpful in a subgroup of patients with non fragile X autism who have similar problems with hyperactivity, hyperarousal and anxiety to those seen in FXS. A second cause of autism is the fragile X premutation but this mechanism of involvement is related to RNA toxicity which perhaps stimulates neuroimmune problems and may mimic other causes of autism. Neurons with the premutation are more vulnerable to environmental toxicity and oxidative stress leading to early cell death. [source]

Hepatitis B virus X mutations occurring naturally associated with clinical severity of liver disease among Korean patients with chronic genotype C infection,

Hyun-Ju Kim
Abstract Few reports have detailed mutation frequencies and mutation patterns in the entire X region according to clinical status. The aims of this study were to elucidate the relationships between mutation patterns and their frequencies in the X region and clinical status in a Korean cohort and determine specific X mutation types, related closely with liver disease progression. All X mutations were determined by direct sequencing in 184 patients with different clinical features. Mutation rates in the X region in patients with more severe liver disease, hepatocellular carcinoma (HCC) (3.6%) or liver cirrhosis (4%) were always significantly higher than in patients with corresponding less severe forms, chronic hepatitis (2.9%) or asymptomatic carriers (2.1%), but no significant difference in mutation rates was found in terms of HBeAg serostatus. All five mutation types (V5M/L, P38S, H94Y, I127T/N, and K130M and V131I) affecting the six codons were found to be related significantly to clinical severity. Among these, two mutation types (V5M/L and K130M and V131I) were observed more frequently in HBeAg negative patients than in HBeAg positive patients. In conclusion, the results suggest that an accumulation of mutations in the X region contributes to disease progression in chronic patients, at least Korean patients with genotype C. Specific mutation types appears to be related more to severe liver diseases such as HCC or liver cirrhosis. In particular, a novel mutation type (V5M/L) discovered firstly during the present study was found to be associated significantly with HCC. J. Med. Virol. 80:1337,1343, 2008. 2008 Wiley-Liss, Inc. [source]

Double inherited thrombophilias and adverse pregnancy outcomes: Fashion or science?

Giovanni Larciprete
Abstract Aim:, To determine to what extent double inherited thrombophilias are associated with adverse obstetric complications correlated with fetoplacental insufficiency, such as preeclampsia, hemolytic anemia elevated liver enzymes and low platelet count (HELLP) syndrome, gestational hypertension, fetal growth restriction (FGR), intrauterine death (ID), abruptio placentae and disseminated intravascular coagulopathy. Methods:, Pregnant women coming to delivery were retrospectively divided into two groups: group A (controls) and group B (cases). Patients belonging to group B had one of the following: severe preeclampsia, HELLP syndrome, gestational hypertension, FGR, intrauterine death, abruptio placentae of disseminated intravascular coagulopathy. We detected methylenetetrahydrofolate reductase (MTHFR) A1298C, MTHFR C677T, factor V Leiden, PAI-1, mutant prothrombin G20210A, plasma homocysteine, antithrombin III, protein S and activated protein C resistance. Normal pregnant women or pregnant women with double defects were enrolled in this study. Results:, The combination of MTHFR C677T mutation with PAI-1 (5G/5G) mutation was significantly linked with the occurrence of ID. HELLP syndrome was significantly related to the simultaneous presence of factor VIII and X mutations. The combination of MTHFR C677T with factor VIII mutation and the combination of factor II and V mutations were significantly related to the occurrence of abruptio placentae. We found an association between double isoforms MTHFR mutation and FGR. Conclusion:, It seems that some thrombophilias and a combination of thrombophilic factors carry a greater risk than others for a given adverse outcome. Further studies are needed to check the link between thrombophilic gene mutations and adverse pregnancy outcomes, such as recurrent miscarriages and deep venous thrombosis. [source]