The shared ancestry between the C9orf72 hexanucleotide repeat expansion and intermediate-length alleles using haplotype sharing trees and HAPTK

The C9orf72 hexanucleotide repeat expansion (HRE) is a common genetic cause of amyotrophic lateral sclerosis (ALS) and frontotemporal dementia (FTD). The inheritance is autosomal dominant, but a high proportion of subjects with the mutation are simplex cases. One possible explanation is de novo expansions of unstable intermediate-length alleles (IAs). Using haplotype sharing trees (HSTs) with the haplotype analysis tool kit (HAPTK), we derived majority-based ancestral haplotypes of HRE samples and discovered that IAs containing ≥18-20 repeats share large haplotypes in common with the HRE. Using HSTs of HRE and IA samples, we demonstrate that the longer IA haplotypes are largely indistinguishable from HRE haplotypes and that several ≥18-20 IA haplotypes share over 5 Mb (>600 markers) haplotypes in common with the HRE haplotypes. These analysis tools allow physical understanding of the haplotype blocks shared with the majority-based ancestral haplotype. Our results demonstrate that the haplotypes with longer IAs belong to the same pool of haplotypes as the HRE and suggest that longer IAs represent potential premutation alleles.

Severe Combined Immunodeficiency-Classification, Microbiology Association and Treatment

Severe combined immunodeficiency (SCID) is a primary inherited immunodeficiency disease that presents before the age of three months and can be fatal. It is usually due to opportunistic infections caused by bacteria, viruses, fungi, and protozoa resulting in a decrease in number and impairment in the function of T and B cells. Autosomal, X-linked, and sporadic forms exist. Evidence of recurrent opportunistic infections and lymphopenia very early in life should prompt immunological investigation and suspicion of this rare disorder. Adequate stem cell transplantation is the treatment of choice. This review aimed to provide a comprehensive approach to the microorganisms associated with severe combined immunodeficiency (SCID) and its management. We describe SCID as a syndrome and summarize the different microorganisms that affect children and how they can be investigated and treated.

A Mobility Model for a 3D Non-Stationary Geometry Cluster-Based Channel Model for High Speed Trains in MIMO Wireless Channels

During channel modeling for high-mobility channels, such as high-speed train (HST) channels, the velocity of the mobile radio station is assumed to be constant. However, this might not be realistic due to the dynamic movement of the train along the track. Therefore, in this paper, an enhanced Gauss-Markov mobility model with a 3D non-stationary geometry based stochastic model (GBSM) for HST in MIMO Wireless Channels is proposed. The non-isotropic scatterers within a cluster are assumed to be around the sphere in which the mobile relay station (MRS) is located. The multi-path components (MPCs) are modeled with varying velocities, whereas the mobility model is a function of time. The MPCs are represented in a death-birth cluster using the Markov process. Furthermore, the channel statistics, i.e., the space-time correlation function, the root-mean-square Doppler shift, and the quasi-stationary interval, are derived from the non-stationary model. The model shows how the quasi-stationary time increases from 0.21 to 0.451 s with a decreasing acceleration of 0.6 to 0.2 m/s2 of the HST. In addition, the impact of the distribution of the angles on the channel statistics is presented. Finally, the simulated results are compared with the measured results. Therefore, there is a close relationship between the proposed model and the measured results, and the model can be used to characterize the channel's properties.

Plasma HMGB1 levels and physical performance in ICU survivors

PURPOSE

Physical impairment after critical illness is recognized as a part of the post-intensive care syndrome (PICS). About one third of intensive care unit (ICU) survivors suffer from long-term physical disability, yet the underlying pathophysiological mechanisms remain poorly understood. The pro-inflammatory alarmin, high mobility group box 1 (HMGB1), promotes muscle dysfunction in experimental models, and HMGB1 stays elevated in some patients after ICU discharge. Accordingly, we investigated the relationship between HMGB1 plasma levels and physical performance in ICU survivors.

METHODS

Prospective cohort study of 100 ICU survivors from the general ICU at the Karolinska University Hospital, Sweden. Patients returned for follow up at 3 (58 patients) and 6 months (51 patients) after ICU discharge. Blood samples were collected, and a 6-minute walk test (6-MWT), a handgrip-strength test (HST), and a timed-stands test (TST) were performed.

RESULTS

Compared to reference values of the different physical tests, 16% of patients underperformed at all tests at 3 months and 12% at 6 months. All test results, except hand-grip strength left, improved significantly over the follow-up period (P < .05). There was no significant association between plasma HMGB1 levels at 3 and 6 months and scores on the three tests (6-MWT, TST, and HST) (P = .50-0.69).

CONCLUSION

In this follow-up study of ICU survivors, we found no significant association between plasma HMGB1 levels and physical performance. Additional follow-up studies of HMGB1 plasma levels and muscle function in ICU survivors are still warranted.

EDITORIAL COMMENT

HMGB-1, a marker of cell damage and activation, is known to increase in ICU patients. In study participants at 3- to 6-month post-ICU stay, HMGB-1 levels were still elevated, although no association to the primary outcome, physical performance, was found. Mechanisms for failure to recover physical performance post-ICU remain unclear, and investigations into cause of post-intensive care syndrome need to continue.

TRIAL REGISTRATIONS

ClinicalTrials.gov identifier NCT02914756.

The impact of rarity in NICE's health technology appraisals

BACKGROUND

In the absence of a framework designed to evaluate medicines for rare diseases in the UK, most orphan medicines are appraised by the National Institute for Health and Care Excellence (NICE) through the Single Technology Appraisal (STA) process.

RESULTS

An analysis of STA appraisals of orphan and non-orphan medicines revealed that orphan medicines were subject to a significantly longer mean time in the NICE process than non-orphan medicines [370 days (n = 44) vs. 277 days (n = 118), p =  < 0.0001]. A higher proportion of orphan STAs required more than one Appraisal Committee Meeting (ACM) versus non-orphan STAs, and orphan STAs were disadvantaged by worse outcomes with respect to positive recommendations than those orphan medicines assessed by Highly Specialised Technology evaluation (HST).

CONCLUSIONS

The uncertainties inherent to developing orphan medicines may contribute to these disadvantages. Improved understanding of the challenges in drug development for orphan medicines and clearer guidance for decision makers on navigating uncertainty in the HTA process may promote greater equity in access to medicines across rare and common conditions.

Validation of the MediByte Portable Monitor for the Diagnosis of Sleep Apnea in Pediatric Patients

STUDY OBJECTIVES

Polysomnography (PSG) is considered the gold standard in the diagnosis of sleep apnea. In pediatric patients, because of limited availability and access to laboratory-based PSG, there can be significant delays in the diagnosis and management of sleep apnea that can result in progressive associated comorbidities. The main objective of the current study was to test the diagnostic value of a portable sleep monitor (PM), the MediByte, in comparison with laboratory PSG in pediatric patients wearing both setups simultaneously.

METHODS

A consecutive series of pediatric patients referred to the University of Illinois Sleep Science Center wore the MediByte during simultaneous PSG. The apnea-hypopnea index (AHI) was calculated for PSG and both manual and autoscoring functions of the PM. Pearson correlation and Bland-Altman plots were assessed.

RESULTS

A total of 70 patients successfully completed simultaneous PSG and PM studies (median age 10.8 years). The AHI obtained both manually and automatically scored PM studies strongly correlated with the AHI obtained from the PSG (r ≥ .932, P < .001). The oxygen saturation obtained by the PM showed significant correlation with that obtained by PSG among children aged 12 to 17 years (P < .001), but not among children aged 7 to 11 years (P ≥ .24). The sensitivity and specificity for detection of severe sleep apnea diagnosed by PSG (AHI ≥ 10 events/h) using both PM scoring methods was very high (> 93% for both).

CONCLUSIONS

Although PSG is still recommended for the diagnosis of sleep apnea, PMs can play a valuable role in diagnosing moderate and severe sleep apnea, especially in older pediatric patients.

COMMENTARY

A commentary on this article appears in this issue on page 685.

Watch Peripheral Arterial Tonometry in the Diagnosis of Pediatric Obstructive Sleep Apnea

Objective To assess the accuracy and clinical reliability of watch peripheral arterial tonometry (PAT) compared with polysomnography (PSG) for the diagnosis of pediatric obstructive sleep apnea (OSA). Study Design Prospective, diagnostic test study. Setting National tertiary referral hospital. Subjects and Methods Patients aged 8 to 15 years with clinically suspected OSA were recruited. All participants underwent PSG and PAT simultaneously in the sleep laboratory. Results Thirty-six patients were included, with a mean age of 10.2 ± 1.8 years. Median (interquartile range) of the apnea hypopnea index (AHI) was 8.0 (5.5-12) and 2.9 (0.5-7.5) events/h, median oxygen desaturation index (ODI) was 2.5 (1.4-8.3) and 1.3 (0.2-3.8) events/h, mean ± standard deviation total sleep time was 398.4 ± 38.3 and 401.9 ± 36.1 minutes, and mean minimum oxygen saturation was 87.1% ± 8.1% and 89.4% ± 7.1% for PSG and PAT sleep parameter results, respectively. Agreement between methods was excellent for the AHI (intraclass correlation coefficient [ICC]: 0.89; 95% CI, 0.40-0.96; P < .001) and ODI (ICC: 0.87; 95% CI, 0.69-0.94; P < .001). Correlation between methods was very good for the ODI ( r = 0.83; 95% CI, 0.67-0.90; P < .001) and moderate for the AHI ( r = 0.64; 95% CI, 0.30-0.85; P < .001). From the receiver operating characteristic curve constructed to assess PAT diagnostic capability, AHI of PAT (W-AHI) at a cutoff of 3.5 events/h provided the highest accuracy (76.9% sensitivity, 78.3% specificity), while W-AHI at 10 events/h yielded 91.3% specificity for diagnosing severe OSA. Conclusion PAT correlated well and had good agreement with PSG. Children with W-AHI ≥10 had high specificity for the diagnosis of severe OSA. Larger studies with PAT designed for children across all age ranges and with a normal control group are still needed.

Potential role of allopregnanolone for a safe and effective therapy of neuropathic pain

Because the treatment and management of neuropathic pain are extremely complicated, the characterization of novel analgesics and neuroprotectors with safe toxicological profiles is a crucial need to develop efficient therapies. Several investigations revealed that the natural neurosteroid allopregnanolone (AP) exerts analgesic, neuroprotective, antidepressant and anxiolytic effects. These effects result from AP ability to modulate GABA(A), glycine, L- and T-type calcium channels. It has been shown that AP treatment induced beneficial actions in humans and animal models with no toxic side effects. In particular, a multi-parametric analysis revealed that AP efficiently counteracted chemotherapy-evoked neuropathic pain in rats. It has also been demonstrated that the modulation of AP-producing enzyme, 3α-hydroxysteroid oxido-reductase (3α-HSOR), in the spinal cord regulates thermal and mechanical pain thresholds of peripheral nerve injured neuropathic rats. The painful symptoms were exacerbated by intrathecal injections of provera (pharmacological inhibitor of 3α-HSOR) which decreased AP production in the spinal cord. By contrast, the enhancement of AP concentration in the intrathecal space induced analgesia and suppression of neuropathic symptoms. Moreover, in vivo siRNA-knockdown of 3α-HSOR expression in healthy rat dorsal root ganglia increased thermal and mechanical pain perceptions while AP evoked a potent antinociceptive action. In humans, blood levels of AP were inversely associated with low back and chest pain. Furthermore, oral administration of AP analogs induced antinociception. Altogether, these data indicate that AP, which possesses a high therapeutic potential and a good toxicological profile, may be used to develop effective and safe strategies against chronic neuropathic pain.