Variants in SCAF4 Cause a Neurodevelopmental Disorder and Are Associated with Impaired mRNA Processing

RNA polymerase II interacts with various other complexes and factors to ensure correct initiation, elongation, and termination of mRNA transcription. One of these proteins is SR-related CTD-associated factor 4 (SCAF4), which is important for correct usage of polyA sites for mRNA termination. Using exome sequencing and international matchmaking, we identified nine likely pathogenic germline variants in SCAF4 including two splice-site and seven truncating variants, all residing in the N-terminal two thirds of the protein. Eight of these variants occurred de novo, and one was inherited. Affected individuals demonstrated a variable neurodevelopmental disorder characterized by mild intellectual disability, seizures, behavioral abnormalities, and various skeletal and structural anomalies. Paired-end RNA sequencing on blood lymphocytes of SCAF4-deficient individuals revealed a broad deregulation of more than 9,000 genes and significant differential splicing of more than 2,900 genes, indicating an important role of SCAF4 in mRNA processing. Knockdown of the SCAF4 ortholog CG4266 in the model organism Drosophila melanogaster resulted in impaired locomotor function, learning, and short-term memory. Furthermore, we observed an increased number of active zones in larval neuromuscular junctions, representing large glutamatergic synapses. These observations indicate a role of CG4266 in nervous system development and function and support the implication of SCAF4 in neurodevelopmental phenotypes. In summary, our data show that heterozygous, likely gene-disrupting variants in SCAF4 are causative for a variable neurodevelopmental disorder associated with impaired mRNA processing.

Phase lag entropy as a hypnotic depth indicator during propofol sedation

Phase lag entropy, an electro-encephalography-based hypnotic depth indicator, calculates diversity in temporal patterns of phase relationship. We compared the performance of phase lag entropy with the bispectral index™ in 30 patients scheduled for elective surgery. We initiated a target-controlled infusion of propofol using the Schnider model, and assessed sedation levels using the Modified Observer's Assessment of Alertness/Sedation scale every 30 s with each stepwise increase in the effect-site propofol concentration. Phase lag entropy and bispectral index values were recorded. The correlation coefficient and prediction probability between phase lag entropy or bispectral index and the sedation level or effect-site propofol concentration were analysed. We calculated baseline variabilities of phase lag entropy and bispectral index. In addition, we applied a non-linear mixed-effects model to obtain the pharmacodynamic relationships among the effect-site propofol concentration, phase lag entropy or bispectral index and sedation level. As sedation increased, phase lag entropy and bispectral index both decreased. The prediction probability values of phase lag entropy and bispectral index for sedation levels were 0.697 and 0.700 (p = 0.261) and for the effect-site concentration of propofol were 0.646 and 0.630 (p = 0.091), respectively. Baseline variability in phase lag entropy and bispectral index was 3.3 and 5.7, respectively. The predicted propofol concentrations, using the Schnider pharmacokinetic model, producing a 50% probability of moderate and deep sedation were 1.96 and 3.01 μg.ml^-1 , respectively. Phase lag entropy was found to be useful as a hypnotic depth indicator in patients receiving propofol sedation.

Heterozygous RNF13 Gain-of-Function Variants Are Associated with Congenital Microcephaly, Epileptic Encephalopathy, Blindness, and Failure to Thrive

Accumulation of unfolded proteins in the endoplasmic reticulum (ER) initiates a stress response mechanism to clear out the unfolded proteins by either facilitating their re-folding or inducing their degradation. When this fails, an apoptotic cascade is initiated so that the affected cell is eliminated. IRE1α is a critical sensor of the unfolded-protein response, essential for initiating the apoptotic signaling. Here, we report an infantile neurodegenerative disorder associated with enhanced activation of IRE1α and increased apoptosis. Three unrelated affected individuals with congenital microcephaly, infantile epileptic encephalopathy, and profound developmental delay were found to carry heterozygous variants (c.932T>C [p.Leu311Ser] or c.935T>C [p.Leu312Pro]) in RNF13, which codes for an IRE1α-interacting protein. Structural modeling predicted that the variants, located on the surface of the protein, would not alter overall protein folding. Accordingly, the abundance of RNF13 and IRE1α was not altered in affected individuals' cells. However, both IRE1α-mediated stress signaling and stress-induced apoptosis were increased in affected individuals' cells. These results indicate that the RNF13 variants confer gain of function to the encoded protein and thereby lead to altered signaling of the ER stress response associated with severe neurodegeneration in infancy.

Development of a new analgesic index using nasal photoplethysmography

Although surrogate measures to quantify pain intensity have been commercialised, there is a need to develop a new index with improved accuracy. The aim of this study was to develop a new analgesic index using nasal photoplethysmography data. The specially designed sensor was placed between the columella and the nasal septum to acquire nasal photoplethysmography in surgical patients. Nasal photoplethysmography and Surgical Pleth Index^® (GE Healthcare) data were obtained for 14 min both in the absence (pre-operatively) or presence (postoperatively) of pain in a group of surgical patients, each patient acting as their own control. Various dynamic photoplethysmography variables were extracted to quantify pain intensity; the most accurate index was selected using logistic regression as a classifier. The area under the curve of the receiver-operating characteristic curve was measured to evaluate the accuracy of final model predictions. In total, 12,012 heart beats from 89 patients were used to develop a new Nasal Photoplethysmography Index for analgesic depth quantification. The two-variable model (a combination of diastolic peak point variation and heart beat interval variation) was most accurate in discriminating between the presence and absence of pain (numerical rating scale (NRS) ≥ 3). The accuracy and area under the curve of the receiver-operating characteristic curve for the Nasal Photoplethysmography Index were 75.3% and 0.8018, respectively, and 64.8% and 0.7034, respectively, for the Surgical Pleth Index. The Nasal Photoplethysmography Index clearly distinguished pain (NRS ≥ 3) in awake surgical patients with postoperative pain. The Nasal Photoplethysmography Index performed better than the Surgical Pleth Index. Further validation studies are needed to evaluate its feasibility to quantify pain intensity during general anaesthesia.

Clinical and radiographic delineation of Bent Bone Dysplasia-FGFR2 type or Bent Bone Dysplasia with Distinctive Clavicles and Angel-shaped Phalanges

Bent Bone Dysplasia-FGFR2 type is a relatively recently described bent bone phenotype with diagnostic clinical, radiographic, and molecular characteristics. Here we report on 11 individuals, including the original four patients plus seven new individuals with three longer-term survivors. The prenatal phenotype included stillbirth, bending of the femora, and a high incidence of polyhydramnios, prematurity, and perinatal death in three of 11 patients in the series. The survivors presented with characteristic radiographic findings that were observed among those with lethality, including bent bones, distinctive (moustache-shaped) small clavicles, angel-shaped metacarpals and phalanges, poor mineralization of the calvarium, and craniosynostosis. Craniofacial abnormalities, hirsutism, hepatic abnormalities, and genitourinary abnormalities were noted as well. Longer-term survivors all needed ventilator support. Heterozygosity for mutations in the gene that encodes Fibroblast Growth Factor Receptor 2 (FGFR2) was identified in the nine individuals with available DNA. Description of these patients expands the prenatal and postnatal findings of Bent Bone Dysplasia-FGFR2 type and adds to the phenotypic spectrum among all FGFR2 disorders. © 2016 Wiley Periodicals, Inc.

2q23.1 microdeletion of the MBD5 gene in a female with seizures, developmental delay and distinct dysmorphic features

We report a 2-year-old female who initially presented with seizures, developmental delay and dysmorphic features and was found to have a 0.3 Mb deletion at chromosome 2q23.1 encompassing the critical seizure gene, MBD5. Her distinct physical features include bifrontal narrowing with brachycephaly, low anterior hairline, hypotonic facial features with short upturned nose, flat nasal bridge, hypertelorism, tented upper lip with everted lower lip, downturned corners of her mouth, and relatively coarse facial features including thickened tongue. She also had a short neck, brachytelephalangy, clinodactyly, and hypertrichosis. At 3½ years she developed progressive ataxia and lost vocabulary at the age of 4. Regression has been reported in one other case of MBD5 deletion. MBD5 is a member of the methyl binding gene family and appears to be responsible for regulating DNA methylation in the central nervous system. Our patient was entirely deleted for the MBD5 gene with partial loss of the EPC2 gene, which suggests that haploinsufficiency of MBD5 is responsible for the distinct phenotype observed. This supports the hypothesis that MBD5 is indeed the critical gene implicated for the findings seen in patients with deletions of chromosome 2q23.1. Further studies are necessary to delineate the role that the MBD5 gene plays in the development of the brain and these specific physical characteristics.

Clinical review of genetic epileptic encephalopathies

Seizures are a frequently encountered finding in patients seen for clinical genetics evaluations. The differential diagnosis for the cause of seizures is quite diverse and complex, and more than half of all epilepsies have been attributed to a genetic cause. Given the complexity of such evaluations, we highlight the more common causes of genetic epileptic encephalopathies and emphasize the usefulness of recent technological advances. The purpose of this review is to serve as a practical guide for clinical geneticists in the evaluation and counseling of patients with genetic epileptic encephalopathies. Common syndromes will be discussed, in addition to specific seizure phenotypes, many of which are refractory to anti-epileptic agents. Divided by etiology, we overview the more common causes of infantile epileptic encephalopathies, channelopathies, syndromic, metabolic, and chromosomal entities. For each condition, we will outline the diagnostic evaluation and discuss effective treatment strategies that should be considered.

2q23.1 microdeletion of the MBD5 gene in a female with seizures, developmental delay and distinct dysmorphic features

We report a 2-year-old female who initially presented with seizures, developmental delay and dysmorphic features and was found to have a 0.3 Mb deletion at chromosome 2q23.1 encompassing the critical seizure gene, MBD5. Her distinct physical features include bifrontal narrowing with brachycephaly, low anterior hairline, hypotonic facial features with short upturned nose, flat nasal bridge, hypertelorism, tented upper lip with everted lower lip, downturned corners of her mouth, and relatively coarse facial features including thickened tongue. She also had a short neck, brachytelephalangy, clinodactyly, and hypertrichosis. At 3½ years she developed progressive ataxia and lost vocabulary at the age of 4. Regression has been reported in one other case of MBD5 deletion. MBD5 is a member of the methyl binding gene family and appears to be responsible for regulating DNA methylation in the central nervous system. Our patient was entirely deleted for the MBD5 gene with partial loss of the EPC2 gene, which suggests that haploinsufficiency of MBD5 is responsible for the distinct phenotype observed. This supports the hypothesis that MBD5 is indeed the critical gene implicated for the findings seen in patients with deletions of chromosome 2q23.1. Further studies are necessary to delineate the role that the MBD5 gene plays in the development of the brain and these specific physical characteristics.

Machine learning methods applied to pharmacokinetic modelling of remifentanil in healthy volunteers: a multi-method comparison

This study compared the blood concentrations of remifentanil obtained in a previous clinical investigation with the predicted remifentanil concentrations produced by different pharmacokinetic models: a non-linear mixed effects model created by the software NONMEM; an artificial neural network (ANN) model; a support vector machine (SVM) model; and multi-method ensembles. The ensemble created from the mean of the ANN and the non-linear mixed effects model predictions achieved the smallest error and the highest correlation coefficient. The SVM model produced the highest error and the lowest correlation coefficient. Paired t-tests indicated that there was insufficient evidence that the predicted values of the ANN, SVM and two multi-method ensembles differed from the actual measured values at alpha = 0.05. The ensemble method combining the ANN and non-linear mixed effects model predictions outperformed either method alone. These results indicated a potential advantage of ensembles in improving the accuracy and reducing the variance of pharmacokinetic models.

Population pharmacokinetic and pharmacodynamic models of remifentanil in healthy volunteers using artificial neural network analysis

AIMS

An ordinary sigmoid E(max) model could not predict overshoot of electroencephalographic approximate entropy (ApEn) during recovery from remifentanil effect in our previous study. The aim of this study was to evaluate the ability of an artificial neural network (ANN) to predict ApEn overshoot and to evaluate the predictive performance of the pharmacokinetic model, and pharmacodynamic models of ANN with respect to data used.

METHODS

Using a reduced number of ApEn instances (n = 1581) to make NONMEM modelling feasible and complete ApEn data (n = 24 509), the presence of overshoot was assessed. A total of 1077 measured remifentanil concentrations and ApEn data, and a total of 24 509 predicted concentrations and ApEn data were used in the pharmacodynamic model A and B of ANN, respectively. The testing subset of model B (n = 7352) was used to evaluate the ability of ANN to predict overshoot of ApEn. Mean squared error (MSE) was calculated to evaluate the predictive performance of the ANN models.

RESULTS

With complete ApEn data, ApEn overshoot was observed in 66.7% of subjects, but only in 37% with a reduced number of ApEn instances. The ANN model B predicted 77.8% of ApEn overshoot. MSE (95% confidence interval) was 57.1 (3.22, 71.03) for the pharmacokinetic model, 0.148 (0.004, 0.007) for model A and 0.0018 (0.0017, 0.0019) for model B.

CONCLUSIONS

The reduced ApEn instances interfered with the approximation of true electroencephalographic response. ANN predicted 77.8% of ApEn overshoot. The predictive performance of model B was significantly better than that of model A.

Changes in visual and auditory response time during conscious sedation with propofol

BACKGROUND

Using a push-button device, we investigated whether visual or auditory response time would increase with increasing sedation, and assessed the responsiveness score of the Observer's Assessment of Alertness/Sedation (OAA/S) scale at the point of first loss of response to visual or auditory stimulation.

METHODS

In experiment 1 we applied visual and auditory stimulation to 19 patients as the propofol target plasma concentration (CPT) was increased to determine whether the visual or auditory response would be lost first. Thirty patients were each then infused with propofol, starting at a CPT of 0.3 microg ml(-1) and increasing by increments of 0.2 microg ml(-1), during which visual (experiment 2) or auditory (experiment 3) stimulation was applied when the effect-site concentration (CE) of propofol reached CPT. Visual response time (VRT), auditory response time (ART), CE and total amounts of propofol, and OAA/S score at the first loss of visual/auditory response were measured.

RESULTS

Visual response disappeared earlier than auditory response in 84.2% of the patients. Visual response time and ART were linearly prolonged as the CE of propofol increased. The CE and total amounts of propofol at the first loss of visual response were 1.2 +/- 0.4 microg ml(-1) and 57.9 +/- 16.7 mg, compared with 1.4 +/- 0.5 microg ml(-1) and 71.6 +/- 26.1 mg, respectively, at the first loss of auditory response. The median (range) OAA/S scores at the first loss of visual and auditory response were 4 (3-4) and 3 (2-4), respectively.

CONCLUSION

VRT and ART were linearly prolonged with increasing sedation. Visual response may be useful in monitoring conscious sedation.

Thermosoftening treatment of the nasotracheal tube before intubation can reduce epistaxis and nasal damage

We evaluated whether a thermosoftening treatment with warm saline of a nasotracheal preformed tube can improve navigability through the nasal passageways and reduce epistaxis and nasal damage. A total of 150 patients were randomly allocated to three groups: Group I (untreated tube group, n = 50), Group II (35 degrees C treated tube group, n = 50), and Group III (45 degrees C treated tube group, n = 50). In Groups II and III, the tubes were softened at 35 +/- 2 degrees C and 45 +/- 2 degrees C with warm saline, respectively. In Group I the tube was prepared at room temperature (25 +/- 2 degrees C). The incidence of epistaxis and nasal damage in Groups II and III was significantly less than that of Group I (P: < 0.05). Despite the more frequent incidence of smooth passage in Group III, no statistical difference was found among the groups. Logistic regression analysis also confirmed that epistaxis was more likely to be reduced when the tube had been thermosoftened (odds ratio = 1.46, 95% confidence interval = 1.02, 2.11). We conclude that simple thermosoftening treatment of the nasotracheal tube with warm saline helps to reduce epistaxis and nasal damage.

IMPLICATIONS

Thermosoftening treatment of a nasotracheal tube with warm saline before intubation can effectively reduce epistaxis and nasal damage. This technique is safe, easy, and suitable for all types of tubes and does not require additional implements.