Pathogenic SCN2A variants cause early-stage dysfunction in patient-derived neurons.

Pathogenic heterozygous variants in SCN2A, which encodes the neuronal sodium channel NaV1.2, cause different types of epilepsy or intellectual disability (ID)/autism without seizures. Previous studies using mouse models or heterologous systems suggest that NaV1.2 channel gain-of-function typically causes epilepsy, whereas loss-of-function leads to ID/autism. How altered channel biophysics translate into patient neurons remains unknown. Here, we investigated iPSC-derived early-stage cortical neurons from ID patients harboring diverse pathogenic SCN2A variants [p.(Leu611Valfs*35); p.(Arg937Cys); p.(Trp1716*)] and compared them with neurons from an epileptic encephalopathy (EE) patient [p.(Glu1803Gly)] and controls. ID neurons consistently expressed lower NaV1.2 protein levels. In neurons with the frameshift variant, NaV1.2 mRNA and protein levels were reduced by ~ 50%, suggesting nonsense-mediated decay and haploinsufficiency. In other ID neurons, only protein levels were reduced implying NaV1.2 instability. Electrophysiological analysis revealed decreased sodium current density and impaired action potential (AP) firing in ID neurons, consistent with reduced NaV1.2 levels. In contrast, epilepsy neurons displayed no change in NaV1.2 levels or sodium current density, but impaired sodium channel inactivation. Single-cell transcriptomics identified dysregulation of distinct molecular pathways including inhibition of oxidative phosphorylation in neurons with SCN2A haploinsufficiency and activation of calcium signaling and neurotransmission in epilepsy neurons. Together, our patient iPSC-derived neurons reveal characteristic sodium channel dysfunction consistent with biophysical changes previously observed in heterologous systems. Additionally, our model links the channel dysfunction in ID to reduced NaV1.2 levels and uncovers impaired AP firing in early-stage neurons. The altered molecular pathways may reflect a homeostatic response to NaV1.2 dysfunction and can guide further investigations.

Association, prediction, generalizability: Cross-center validity of predicting tooth loss in periodontitis patients.

OBJECTIVES: To predict patients' tooth loss during supportive periodontal therapy across four German university centers. METHODS: Tooth loss in 897 patients in four centers (Kiel (KI) n = 391; Greifswald (GW) n = 282; Heidelberg (HD) n = 175; Frankfurt/Main (F) n = 49) during supportive periodontal therapy (SPT) was assessed. Our outcome was annualized tooth loss per patient. Multivariable linear regression models were built on data of 75 % of patients from one center and used for predictions on the remaining 25 % of this center and 100 % of data from the other three centers. The prediction error was assessed as root-mean-squared-error (RMSE), i.e., the deviation of predicted from actually lost teeth per patient and year. RESULTS: Annualized tooth loss/patient differed significantly between centers (between median 0.00 (interquartile interval: 0.00, 0.17) in GW and 0.09 (0.00, 0.19) in F, p = 0.001). Age, smoking status and number of teeth before SPT were significantly associated with tooth loss (p < 0.03). Prediction within centers showed RMSE of 0.14-0.30, and cross-center RMSE was 0.15-0.31. Predictions were more accurate in F and KI than in HD and GW, while the center on which the model was trained had a less consistent impact. No model showed useful predictive values. CONCLUSION: While covariates were significantly associated with tooth loss in linear regression models, a clinically useful prediction was not possible with any of the models and generalizability was not given. Predictions were more accurate for certain centers. CLINICAL RELEVANCE: Association should not be confused with predictive value: Despite significant associations of covariates with tooth loss, none of our models was useful for prediction. Usually, model accuracy was even lower when tested across centers, indicating low generalizability.

Long-term tooth retention in periodontitis patients in four German university centres.

OBJECTIVES: In this retrospective study, we compared tooth loss between patients receiving periodontal therapy (PT) in four German university centres, stratified according to periodontal treatment phase. MATERIALS AND METHODS: Overall, 896 patients (Kiel (KI) n = 391; Greifswald (GW) n = 282; Heidelberg (HD) n = 174; Frankfurt a.M. (F) n = 49) were examined initially (T0), after active periodontal therapy (APT, T1) and after supportive periodontal therapy (SPT, T2). Descriptive analyses and multivariable negative binomial regression models were performed. RESULTS: Follow-up periods differed significantly between the centres, ranging between 6.7 ±â€¯3.0 (GW) and 18.2 ±â€¯5.5 (KI) years (p < 0.001). At T0, age, gender, smoking and diabetes showed notable regional distinctions (p < 0.001). However, the number of teeth per patient was similar (between 24.0 ±â€¯4.6 (F) and 24.5 ±â€¯4.1 (HD); p = 0.27). During PT, the number of extracted teeth differed significantly between centres, with greater differences during SPT (0.9 ±â€¯1.8 (GW) to 2.3 ±â€¯2.8 (KI), p < 0.001) compared to APT (0.4 ±â€¯0.9 (F) to 1.0 ±â€¯2.1 (KI), p = 0.02). Annual tooth loss during SPT remained low in all centres (between 0.10 ±â€¯0.14 (F) to 0.15 ±â€¯0.30 (HD), p < 0.001). CONCLUSION: Within the limitation of the study, PT leads to a low risk of tooth loss in all university centres irrespective of patients' baseline characteristics. CLINICAL RELEVANCE: Within the limitations of this retrospective investigation, long-term tooth retention seems to be feasible for most patients, as long as a systematic and structured treatment approach is applied.

Epidemiology of cyprinid herpesvirus-3 infection in latently infected carp from aquaculture.

Cyprinid herpesvirus-3 (CyHV-3, koi herpesvirus, KHV) is the causative agent of an economically important disease in carp. The mode of transmission of this virus, especially how the infectious agent is introduced into ponds de novo, is not known in detail. The aim of this study was to investigate the shedding of CyHV-3 from fish with latent infections, under aquaculture conditions. Ponds in Saxony, Germany, with latently infected carp were examined at different times during the production cycle to investigate the influence of fish farming procedures on virus activation and shedding. Carp and water samples were investigated by quantitative real-time PCR. Some of the latently infected carp shed CyHV-3. Virus shedding was induced mainly when the ponds were drained and the carp either harvested or moved to different ponds, and was independent of the water temperature. This indicated that during these times there was a risk that effluent water from the ponds could disseminate the infectious agent. During summer, on-growing carp are infected with low numbers of CyHV-3. These findings are important for disease management strategies in carp aquaculture and for the design of testing protocols for the detection of latent infection in carp populations.

Do wild fish species contribute to the transmission of koi herpesvirus to carp in hatchery ponds?

The koi herpesvirus (KHV) has spread worldwide since its discovery in 1998 and causes disease and mortality in koi and common carp populations with a high impact on the carp production industry. Many investigations have been conducted to examine ways of distribution and to identify possible transmission vectors. The answers, however, raise many new questions. In the present study, different wild fish species taken from carp ponds with a history of KHV infection were examined for their susceptibility to the virus. In the tissue of these fish, the virus load was determined and it was tested whether a release of the virus could be induced by stress and the virus then could be transferred to naive carp. Wild fish were gathered from carp ponds during acute outbreaks of virus-induced mortality in summer and from ponds stocked with carp carrying a latent KHV infection. From these ponds, wild fish were collected during the harvesting process in autumn or spring when the ponds were drained. We found that regardless of season, temperature variation, age and infection status of the carp stock, wild fish from carp ponds and its outlets could be tested positive for the KHV genome using real-time PCR with a low prevalence and virus load. Furthermore, virus transfer to naive carp was observed after a period of cohabitation. Cyprinid and non-cyprinid wild fish can therefore be considered as an epidemiological risk for pond carp farms.

Analysis of quality and feasibility of an objective structured clinical examination (OSCE) in preclinical dental education.

INTRODUCTION: An objective structured clinical examination (OSCE) has been implemented in preclinical dentistry. It was taken at an early stage (propaedeutics course). The objectives of this study were to evaluate the reliability, validity, and feasibility of the examination, and the effect of circuit number on OSCE score. METHODS: The OSCE was designed by an expert committee on the basis of pre-reviewed blueprints and checklists. Eleven stations formed an interdisciplinary circuit. Six groups of students (n = 62) passed sequentially round the same circuit. Statistical analysis was performed by using SPSS. Reliability was determined by measurement of internal consistency (Cronbach's α, Guttman's λ(2) ), standard error of measurement (SEM) (comprising generalisability index α, dependability index ϕ and pass 150;fail reliability p(c) ), consistency coefficient κ, item 150;scale correlation (Pearson correlation), and, because the unidimensionality of the stations could not be assumed, factor analysis including varimax rotation. Convergent validity (Pearson correlation, t-test), and predictive validity for future preclinical courses and the final preclinical examination were assessed by analysis of variance (ANOVA). The effect of the circuit number on score improvement was calculated, including a correction for the general competence of the students (ANOVA). Cost was calculated on the basis of the time invested. RESULTS: Fifty-three out of sixty-two students passed the OSCE (mean score: 67%, SD 7.7, range, 47-81). Scores for each station correlated significantly with total scores (r = 0.35-0.54, P < 0.01). For internal consistency, α = 0.75 (relative SEM 3.8) and λ(2) = 0.766. The dependability index was ϕ = 0.694 (absolute SEM 4.4), p(c) = 0.89 and κ = 0.61. Factor analysis yielded two components: dental-materials-oriented stations and all other stations (explained variance 43%). Scores correlated significantly with success in passing practical tests (i.e. performing dental procedures under examination conditions) (known group validity, P < 0.01) and with scores for subsequent courses and the final preclinical examination (Physikum) (predictive validity, P < 0.001). Later groups performed 4% better on average (CI 95%: 1.2-6.8%; P < 0.01). The cost was 181 Euro per student. CONCLUSIONS: The OSCE is reliable and valid in the context of preclinical dentistry. The cost is substantial. The problem of improvement of students' results with ascending circuit number has to be addressed.

["Constanze": a trinational project on avian influenza in wild birds at Lake Constance]. / Projekt "Constanze": Erkenntnisse aus drei Jahren aviärer Influenza-Forschung im Bodenseegebiet.

When highly pathogenic avian influenza H5N1 (HPAI H5N1) arrived at Lake Constance in February 2006, little was known about its ecology and epidemiology in wild birds. In order to prevent virus transmission from wild birds to poultry, the adjacent countries initiated the tri-national, interdisciplinary research program «Constanze¼ to investigate avian influenza infections in water birds at Lake Constance. In collaboration with government agencies scientists examined the prevalence of AI virus in the region of Lake Constance for a period of 33 months, compared the effectiveness of different surveillance methods and analysed the migration behaviour of water birds. Although virus introduction from regions as far as the Ural Mountains seemed possible based on the migration behaviour of certain species, no influenza A viruses of the highly pathogenic subtype H5N1 (HPAIV) was found. However, influenza A viruses of different low pathogenic subtypes were isolated in 2.2 % of the sampled birds (swabs). Of the different surveillance methods utilised in the program the sampling of so called sentinel birds was particularly efficient.

A homoallelic FECH mutation in a patient with both erythropoietic protoporphyria and palmar keratoderma.

BACKGROUND: Erythropoietic protoporphyria (EPP) is a hereditary disorder caused by the deficiency of ferrochelatase (FECH) in the haem biosynthetic pathway. In the majority of families, EPP is transmitted as a pseudodominant trait. Autosomal recessive form of EPP is found in only about 3% of the families. OBJECTIVES: In this study, we describe a 6-year-old boy who suffered from both EPP and palmar keratoderma. METHODS AND RESULTS: A novel homoallelic missense mutation (p.Ser318Tyr) was identified in the FECH gene. In addition, a region of homozygosity of approximately 6.8 Mb was observed in chromosome 18 of the patient by both microsatellite and SNP array. The parents of the patient, both of Palestinian (Jordanian) origin, were heterozygous for the S318Y mutation, although no history of consanguinity was known. Microsatellite genotyping identified a partial haplotype from each parent that corresponds to the region of homozygosity in the patient. Assuming S318Y is a founder mutation, the number of generations separating the two parents from their common ancestor from whom they inherited S318Y was estimated as 21.7 (95% CI 3.42­69.7). CONCLUSION: EPP was therefore inherited as an autosomal recessive trait in the family. This study confirms the association between palmar keratoderma and autosomal recessive EPP.

Epigenetic mutations of the imprinted IGF2-H19 domain in Silver-Russell syndrome (SRS): results from a large cohort of patients with SRS and SRS-like phenotypes.

BACKGROUND: Silver-Russell syndrome (SRS) is a clinically and genetically heterogeneous condition characterised by severe intrauterine and postnatal growth retardation. Loss of DNA methylation at the telomeric imprinting control region 1 (ICR1) on 11p15 is an important cause of SRS. METHODS: We studied the methylation pattern at the H19-IGF2 locus in 201 patients with suspected SRS. In an attempt to categorise the patients into different subgroups, we developed a simple clinical scoring system with respect to readily and unambiguously assessable clinical features. In a second step, the relationship between clinical score and epigenetic status was analysed. RESULTS AND CONCLUSIONS: The scoring system emerged as a powerful tool for identifying those patients with both a definite SRS phenotype and carrying an epimutation at 11p15. 53% of the 201 patients initially enrolled fulfilled the criteria for SRS and about 40% of them exhibited an epimutation at the H19-IGF2 locus. Methylation defects were restricted to patients who fulfilled the diagnostic criteria for SRS. Patients carrying epimutations had a more severe phenotype than either the SRS patients with mUPD7 or the idiopathic SRS patients. The majority of patients with methylation abnormalities showed hypomethylation at both the H19 and IGF2 genes. However, we also identified SRS patients where hypomethylation was restricted to either the H19 or the IGF2 gene. Interestingly, we detected epimutations in siblings of normal parents, most likely reflecting germ cell mosaicism in the fathers. In one family, we identified an epimutation in an affected father and his likewise affected daughter.

Duplications in addition to terminal deletions are present in a proportion of ring chromosomes: clues to the mechanisms of formation.

BACKGROUND AND METHODS: Ring chromosomes are often associated with abnormal phenotypes because of loss of genomic material at one or both ends. In some cases no deletion has been detected and the abnormal phenotype has been attributed to mitotic ring instability. We investigated 33 different ring chromosomes in patients with phenotypic abnormalities by array based comparative genomic hybridisation (CGH) and fluorescence in situ hybridisation (FISH). RESULTS: In seven cases we found not only the expected terminal deletion but also a contiguous duplication. FISH analysis in some of these cases demonstrated that the duplication was inverted. Thus these ring chromosomes derived through a classical inv dup del rearrangement consisting of a deletion and an inverted duplication. DISCUSSION: Inv dup del rearrangements have been reported for several chromosomes, but hardly ever in ring chromosomes. Our findings highlight a new mechanism for the formation of some ring chromosomes and show that inv dup del rearrangements may be stabilised not only through telomere healing and telomere capture but also through circularisation. This type of mechanism must be kept in mind when evaluating possible genotype-phenotype correlations in ring chromosomes since in these cases: (1) the deletion may be larger or smaller than first estimated based on the size of the ring, with a different impact on the phenotype; and (2) the associated duplication will in general cause further phenotypic anomalies and might confuse the genotype-phenotype correlation. Moreover, these findings explain some phenotypic peculiarities which previously were attributed to a wide phenotypic variation or hidden mosaicism related to the instability of the ring.

[Avian influenza: wildbird monitoring in Switzerland between 2003-2006]. / Aviäre Influenza: Wildvogelmonitoring in der Schweiz zwischen 2003-2006.

During various surveillance programs more than 3500 cloacal swabs and organ samples from songbirds, waterbirds and poultry have been tested for avian influenza using real time RT-PCR. Switzerland carried out the first wildbird monitoring between autumn 2003 and spring 2005. 1053 samples, mostly from songbirds, were tested. LPAI-strains were found in two cases. A second intensified surveillance program started in October 2005 along with the first ban on free range poultry farming. Until the end of April 2006 2455 cloacal swabs from dead wildbirds have been analysed. By the end of february H5N1 was for the first time detected in Switzerland and by the end of march 32 waterbirds have been found positive for H5N1. 146 poultry flocks with a special permission for free range management proved to be AI negative.

Initial maternal meiotic I error leading to the formation of a maternal i(2q) and a paternal i(2p) in a healthy male.

We report on the investigation of the parental origin and mode of formation of the two isochromosomes, i(2p) and i(2q), detected in a healthy adult male. Conventional cytogenetic analysis revealed the proband's lack of structurally normal chromosomes 2, these being replaced by an i(2p) and an i(2q). Investigation of the parental origin of the isochromosomes revealed a paternal origin of the i(2p) chromosome and a maternal origin of the i(2q) chromosome. Thus, the formation of both isochromosomes, or at least of the paternal i(2p), appears to have occurred postzygotically. Interestingly, whilst a paternal isodisomy was observed for the entire 2p, maternal heterodisomy was detected for two segments of 2q, separated by a segment showing isodisomy. The results are indicative of an initial error (non-disjunction or i(2q) formation) concerning the maternal chromosomes 2 during meiosis I, which likely favored the subsequent mitotic recombination event resulting in the presence of two isochromosomes. To the best of our knowledge this is the first case of an initial meiotic error, followed by postzygotic trisomy rescue through the formation of isochromosomes, resulting in a normal phenotype. A prenatal detection, by cytogenetic and molecular analysis, of such chromosome abnormality would have led to the incorrect conclusion of a most likely poor prognosis for the fetus.

Jacobsen syndrome and Beckwith-Wiedemann syndrome caused by a parental pericentric inversion inv(11)(p15q24).

Here we report on a male infant presenting the typical pattern of Jacobsen syndrome including trigonocephaly, thrombocytopenia, congenital heart defect, urethral stenosis, and partial agenesis of the corpus callosum. Conventional karyotyping, FISH, SKY and CGH analyses showed that the region distal to the MLL locus on 11q23 was lost and replaced by the distal region of 11p, leading to a partial trisomy of 11p and a partial monosomy of 11q. According to ISCN (1995) the karyotype can be described as 46,XY,add(11)(q2?3). ish 11ptel(D11S2071x3),11qtel(VIJyRM2072x1). Array-CGH analysis allowed us to narrow down the breakpoints to 11p15.1 and 11q24.1. Methylation analyses of genes located on 11p showed an increased level of the non-methylated paternal allele of the KCNQ1OT1 gene, confirming the concomitant presence of Beckwith-Wiedemann syndrome (BWS). The phenotype resulting from the 11q deletion seems to dominate the phenotype due to the distal 11p trisomy. Investigation of the parents revealed that this chromosomal rearrangement was caused by a paternal pericentric inversion inv(11)(p15q24). Since chromosomal aberrations like the one described here can easily be overlooked during routine chromosome analysis, combined FISH analysis using subtelomeric and possibly additional probes should be applied if there is any doubt about the integrity of telomeric regions.

Clinical profiles of four patients with Rett syndrome carrying a novel exon 1 mutation or genomic rearrangement in the MECP2 gene.

Rett syndrome (RTT) is a neurodevelopmental disorder caused by mutations in the X-linked MECP2 gene encoding methyl CpG binding protein 2 (MeCP2). Recently, a new isoform of MeCP2 including exon 1 was identified. This new isoform is more abundantly expressed in brain than the isoform including exons 2-4. Very little is known about the phenotypes associated with mutations in exon 1 of MECP2 since only a limited number of RTT patients carrying such mutations have been identified so far. In this study, we screened a cohort of 20 girls with RTT for exon 1 mutations by sequencing and multiplex ligation-dependent probe amplification (MLPA). We identified one girl with a novel exon 1 mutation (c.30delCinsGA) by sequencing and three with genomic rearrangements by MLPA. Comparison of the phenotypes showed that the girls carrying a mutation or rearrangement encompassing exon 1 were more severely affected than the girls with rearrangements not affecting exon 1.

M-FISH applications in clinical genetics.

Until recently, presence of de novo marker or derivative chromosomes was quite problematic for genetic counseling especially in prenatal diagnosis, because characterization of marker and derivative chromosomes by conventional cytogenetic techniques was nearly impossible. However, recently developed molecular cytogenetic technique named Multicolor Fluorescence in Situ Hybridization (M-FISH) which paints all human chromosomes in 24 different colors allows us to characterize marker and derivative chromosomes in a single hybridization. In this study, we applied M-FISH to determine the origin of 3 marker and 3 derivative chromosomes. Marker chromosomes were found to originate from chromosome 15 in two postnatal and one prenatal case. Of these, one of the postnatal cases displayed clinical findings of inv dup (115) syndrome and the other of infertility, and the prenatal case went through amniocentesis due to the triple test results. Karyotypes of the patients with derivative chromosomes were designated as 46,XY,der (21)t(1;21)(q32;p11), 46,XX,der(8)t(8;9)(p23;p22) and 46,XX,der(18)t(18;20)(q32;p11.2) according to cytogenetic and M-FISH studies. All of the M-FISH results were confirmed with locus specific or whole chromosome painting probes. The case with der (8)t(8;9) had trisomy 9(p22-pter) and monosomy 8(p23-pter) due to this derivative chromosome. The case with der(18)t(18;20) had trisomy 20(p11.2-pter) and monosomy 18(q32-qter). Parental origins of the derivative chromosomes were analyzed using microsatellite markers located in the trisomic chromosomal segments. Patients' clinical findings were compared with the literature.

Unbalanced 18q/21q translocation in a patient previously reported as monosomy 21.

We describe a patient in whom full monosomy 21 was initially assumed from routine GTG-banded karyotyping. Re-examination with chromosome painting demonstrated an unbalanced translocation between the long arms of chromosomes 18 and 21. Fluorescence in situ hybridisation (FISH) and microsatellite marker analysis revealed partial monosomy of chromosome 21 (pter-q21) and 18(q22-qter). The patient, 18 years old at the second examination, revealed multiple dysmorphic features, genital hypoplasia, dilated cerebral ventricles, muscular hypotonia and severe mental retardation. In not one out of all patients investigated postnatally in whom an initial examination had revealed monosomy 21, this could be confirmed by FISH; in all of them, re-examination detected an unbalanced rearrangement leading to only partial monosomy 21 plus partial monosomy of another chromosome to which the distal 21q segment was attached. Thus, it is still highly likely that full monosomy 21 is incompatible with intra-uterine survival.

A case with de novo interstitial deletion of chromosome 7q21.1-q22.

A case with de novo interstitial deletion of chromosome 7q21.1-q22: A patient with multiple congenital anomalies was found to have a de novo proximal interstitial deletion of chromosome 7q21.1-q22. The patient was 10.5 years of age, and manifestations include growth retardation (below 3rd percentile), mental retardation, mild microcephaly, hypersensitivity to noise, mild spasticity, short palpebral fissures, alternant exotropia, compensated hypermetropic astigmatism, hypotelorism, hypoplastic labia majora and minora, clinodactyly of fingers 4 and 5. Molecular studies revealed that the deletion had a paternal origin, while chromosomes of both parents cytogenetically were shown to be normal. Molecular, and fluorescence in situ hybridization (FISH) analyses confirmed no deletion at the Williams-Beuren Syndrome region. Some of the heterogeneous clinical findings were consistent with previously reported cases of same chromosomal breakpoints.

Strong temperature dependence of irradiation effects in organic layers.

Radiation damage of self-assembled monolayers, which are prototypes of thin organic layers and highly organized biological systems, shows a strong dependence on temperature. Two limiting cases could be identified. Reactions involving transport of single atoms and small fragments proceed nearly independent of temperature. Reactions requiring transport of heavy fragments are, however, efficiently quenched by cooling. We foresee the combined use of temperature and irradiation by electrons or photons for advanced tailoring of self-assembled monolayers on surfaces. In addition, our results have direct implications for cryogenic approaches in advanced electron and x-ray microscopy and spectroscopy of biological macromolecules and cells.