Two new Rett syndrome families and review of the literature: expanding the knowledge of MECP2 frameshift mutations

<p>Abstract</p> <p>Background</p> <p>Rett syndrome (RTT) is an X-linked dominant neurodevelopmental disorder, which is usually caused by <it>de novo </it>mutations in the <it>MECP2 </it>gene. More than 70% of the disease causing <it>MECP2 </it>mutations are eight recurrent C to T transitions, which almost exclusively arise on the paternally derived X chromosome. About 10% of the RTT cases have a C-terminal frameshift deletion in <it>MECP2</it>. Only few RTT families with a segregating <it>MECP2 </it>mutation, which affects female carriers with a phenotype of mental retardation or RTT, have been reported in the literature. In this study we describe two new RTT families with three and four individuals, respectively, and review the literature comparing the type of mutations and phenotypes observed in RTT families with those observed in sporadic cases. Based on these observations we also investigated origin of mutation segregation to further improve genetic counselling.</p> <p>Methods</p> <p><it>MECP2 </it>mutations were identified by direct sequencing. XCI studies were performed using the X-linked androgen receptor (<it>AR</it>) locus. The parental origin of <it>de novo MECP2 </it>frameshift mutations was investigated using intronic SNPs.</p> <p>Results</p> <p>In both families a C-terminal frameshift mutation segregates. Clinical features of the mutation carriers vary from classical RTT to mild mental retardation. XCI profiles of the female carriers correlate to their respective geno-/phenotypes. The majority of the <it>de novo </it>frameshift mutations occur on the paternally derived X chromosome (7/9 cases), without a paternal age effect.</p> <p>Conclusions</p> <p>The present study suggests a correlation between the intrafamilial phenotypic differences observed in RTT families and their respective XCI pattern in blood, in contrast to sporadic RTT cases where a similar correlation has not been demonstrated. Furthermore, we found <it>de novo MECP2 </it>frameshift mutations frequently to be of paternal origin, although not with the same high paternal occurrence as in sporadic cases with C to T transitions. This suggests further investigations of more families. This study emphasizes the need for thorough genetic counselling of families with a newly diagnosed RTT patient.</p

Immigrants from conflict-zone countries: an observational comparison study of obstetric outcomes in a low-risk maternity ward in Norway

Background Immigrants have higher risks for some adverse obstetric outcomes. Furthermore, refugees are reported to be the most vulnerable group. This study compared obstetric outcomes between immigrant women originating from conflict-zone countries and ethnic Norwegians who gave birth in a low-risk setting. Methods This was a population-based study linking the Medical Birth Registry of Norway to Statistics Norway. The study included the first registered birth during the study period of women from Somalia (n = 278), Iraq (n = 166), Afghanistan (n = 71), and Kosovo (n = 67) and ethnic Norwegians (n = 6826) at Baerum Hospital from 2006–2010. Background characteristics and obstetric outcomes of each immigrant group were compared with ethnic Norwegians with respect to proportions and risks calculated by logistic regression models. Results In total, 7408 women and their births were analyzed. Women from Somalia were most at risk for adverse obstetric outcomes. Compared with ethnic Norwegians, they had increased odds ratios (OR) for emergency cesarean section (OR 1.81, CI 1.17–2.80), postterm birth (OR 1.93, CI 1.29–2.90), meconium-stained liquor (OR 2.39, CI 1.76–3.25), and having a small-for-gestational-age infant (OR 3.97, CI 2.73–5.77). They had a reduced OR for having epidural analgesia (OR 0.40, CI 0.28–0.56) and a large-for-gestational-age infant (OR 0.32, CI 0.16–0.64). Women from Iraq and Afghanistan had increased risk of having a small-for-gestational-age infant with OR of 2.21 (CI 1.36–3.60) and 2.77 (CI 1.42–5.39), respectively. Iraqi women also had reduced odds ratio of having a large-for-gestational-age infant (OR 0.35, CI 0.15–0.83). Women from Kosovo did not differ from ethnic Norwegians in any of the outcomes we tested. Conclusions Even in our low-risk maternity ward, women originating from Somalia were at the greatest risk for adverse obstetric outcomes in the compared groups. We could not find the same risk among the other immigrant women, also originating from conflict-zone countries. Several factors may influence these findings, and this study suggests that immigrant women from Somalia need more targeted care during pregnancy and childbirth

Habiliteringsopphold i varmt klima for barn med Cerebral Parese – Foreldre og barnas opplevelse av deltakelse og mestring

The article describes the results from a case-control study investigating the effect of a habilitation program in warm climate involving 60 children with Cerebral Palsy aged six to 18. The study was performed during the spring 2003 and 2004 as part of a project, initiated and funded by the Norwegian Social and Health Department with the aim to investigate physical and social effects of habilitation in a warm climate. The purpose of this article is to describe social participation and coping before and after participation. Registrations of mental health and self-esteem were performed before and after the program and at three and six weeks after finishing the program. The outcome measures were the Child Behavior Checklist (CBCL), Youth Self-Report (YSR) og Self-Perception Profile for Adolescents (SPPA). At the end of the program we performed group interviews with the parents. After finishing the program, a significant reduction in behaviour and emotional problems among the children and the parents were registered, and the childrens competence in school and self-perception was improved. The result shows that the majority of children experienced improved self-coping, gained new friends and meeting families with disabled children had a positive effect. The change in all areas was maintained at three and six weeks after the program, and the results from the group interview and the questionnaires were coherent. The study showed that in the discussion about best practice in habilitation of children with CP, a focus on participation and coping is highly relevant

Kynurenine pathway in Autism Spectrum Disorders in children

Background: There is increasing evidence that altered immune responses play a role in the pathogenesis of autism spectrum disorders (ASD), together with dysfunction of the serotonergic and glutamatergic systems. Since the kynurenine (KYN) pathway that degrades tryptophan (TRP) is activated in various neuroinflammatory states, we aimed to determine whether this pathway is activated in ASD. Methods: Sixty-five pediatric ASD patients (including 52 boys) were enrolled from an epidemiological survey covering 2 counties in Norway; 30 (46.5%) of these patients were diagnosed with childhood autism, 16 (24.6%) with Asperger syndrome, 12 (18.5%) with atypical autism, 1 (1.5%) with Rett syndrome, and 6 (9.2%) with other ASD. The serum levels of the following markers were measured in the children with ASD and compared to those in 30 healthy children: TRP, KYN, kynurenic acid (KA), 3-hydroxykynurenine, and quinolinic acid. Results: The mean serum level of KA was significantly lower in the ASD group than in the healthy controls (28.97 vs. 34.44 nM, p = 0.040), while the KYN/KA ratio was significantly higher in the ASD group (61.12 vs. 50.39, p = 0.006). The same relative values were found when comparing the childhood autism subgroup with the controls. Also, the mean serum level of TRP was significantly lower in children with a subdiagnosis of childhood autism than in those with Asperger syndrome (67.26 vs. 77.79 μM, p = 0.020). Conclusion: Our study indicates that there is an increased neurotoxic potential and also a possible lower KYN aminotransferase activity in ASD

De novo mutations in SCN1A are associated with classic Rett syndrome: a case report

Background Rett syndrome (RTT) is a neurodevelopmental disorder. In more than 95% of females with classic RTT a pathogenic mutation in MECP2 has been identified. This leaves a small fraction of classic cases with other genetic causes. So far, there has not been reported any other gene that may account for the majority of these cases. Case presentation We describe two females who fulfill the diagnostic criteria for classic RTT, with pathogenic de novo mutations in SCN1A, which usually leads to Dravet syndrome. The developmental history and clinical features of these two females fits well with RTT, but they do have an unusual epileptic profile with early onset of seizures. Investigation of mRNA from one of the females showed a significantly reduced level of MECP2 mRNA. Conclusions To our knowledge, this is the first report suggesting that SCN1A mutations could account for a proportion of the females with classic RTT without MECP2 mutations. As a consequence of these findings SCN1A should be considered in the molecular routine screening in MECP2-negative individuals with RTT and early onset epilepsy

Genetic and clinical variations in a Norwegian sample diagnosed with Rett syndrome

Background and purpose: Rett syndrome (RTT) is a neurodevelopmental disorder mainly caused by mutations in MECP2. The diagnostic criteria of RTT are clinical; mutations in MECP2 are neither diagnostic nor necessary, and a mutation in another gene does not exclude RTT. We attempted to correlate genotype and phenotype to see if there are significant clinical associations. Methods: All available females diagnosed with RTT in Norway were invited to the study. Parents were interviewed, the girl or woman with RTT examined and medical records reviewed. All diagnoses were revisited according to the current diagnostic criteria and exome-based sequencing analyses were performed in individuals without an identified causative mutation. Participants were categorized according to genotypes and RTT diagnosis. Individuals with RTT with and without mutations in MECP2 were compared. Results: Ninety-one individuals were included. A presumed causative mutation was identified in 86 individuals, of these, mutations in MECP2 in 77 individuals and mutations in SMC1A, SYNGAP1, SCN1A, CDKL5, FOXG1 or chromosome 13q in nine. Seventy-two individuals fulfilled the diagnostic criteria for classic and 12 for atypical RTT. Significant differences in early development, loss of hand use and language, intense eye gaze and the presence of early onset epilepsy were revealed in individuals with RTT according to their MECP2 genotypic status. Conclusion: Using the current diagnostic criteria, genetic and clinical variation in RTT is considerable. Significant differences between individuals with RTT with and without MECP2 mutations indicate that MECP2 is a major determinant for the clinical phenotype in individuals with RTT. Keywords: Clinical phenotype; Epilepsy; Exome sequencing; Genetic variation; MECP2; Rett syndrome

A Fatal, Systemic Mitochondrial Disease with Decreased Mitochondrial Enzyme Activities, Abnormal Ultrastructure of the Mitochondria and Deficiency of Heat Shock Protein 60

We report on a girl presenting with facial dysmorphic features and breathing difficulties upon birth. She was hypotonic, developed a metabolic acidosis, and died two days old of heart failure. Post-mortem examination revealed abnormalities of brain, lungs, heart and liver. In cultured skin fibroblasts activities of enzymes of oxidative phosphorylation, pyruvate metabolism, beta-oxidation and other mitochondrial (mt) metabolic pathways were markedly decreased. Activities of enzymes localized in the mt outer membrane or in other cell organelles were found to be normal. The mitochondria appeared swollen and were located mainly around the nucleus. Electron micrographs showed locally disintegrated mt inner membranes and large mt vacuoles. The amount of mt heat shock protein 60 (hsp60) was about one fifth of that in controls. We conclude that this mt disorder is most likely caused by defective synthesis and maintenance of mitochondria, possibly due to a defect in mt protein import or enzyme assembly resulting from deficiency of hsp60.