Exploring the utility of whole‐exome sequencing as a diagnostic tool in a child with atypical episodic muscle weakness

The advent of whole‐exome next‐generation sequencing (WES) has been pivotal for the molecular characterization of Mendelian disease; however, the clinical applicability of WES has remained relatively unexplored. We describe our exploration of WES as a diagnostic tool in a 3½‐year old female patient with a 2‐year history of episodic muscle weakness and paroxysmal dystonia who presented following a previous extensive but unrevealing diagnostic work‐up. WES was performed on the proband and her two parents. Parental exome data was used to filter potential de novo genomic events in the proband and suspected variants were confirmed using di‐deoxy sequencing. WES revealed a de novo non‐synonymous mutation in exon 21 of the calcium channel gene CACNA1S that has been previously reported in a single patient as a rare cause of atypical hypokalemic periodic paralysis. This was unexpected, as the proband's original differential diagnosis had included hypokalemic periodic paralysis, but clinical and laboratory features were equivocal, and standard clinical molecular testing for hypokalemic periodic paralysis and related disorders was negative. This report highlights the potential diagnostic utility of WES in clinical practice, with implications for the approach to similar diagnostic dilemmas in the future.     

Ageing effects on knee and ankle joint angles at key events and phases of the gait cycle

The objective of this research was to determine whether joint angles at critical gait events and during major energy generation/absorption phases of the gait cycle would reliably discriminate age-related degeneration during unobstructed walking. The gaits of 24 healthy adults (12 young and 12 elderly) were analysed using the PEAK Motus motion analysis system. The elderly participants showed significantly greater single (60.3% versus 62.3%, p < 0.01) and double ( p < 0.05) support times, reduced knee flexion (47.7° versus 43.0°, p < 0.05) and ankle plantarflexion (16.8° compared to 3.3°, p = 0.053) at toe off, reduced knee flexion during push-off and reduced ankle dorsiflexion (16.8° compared to 22.0°, p < 0.05) during the swing phase. The plantarflexing ankle joint motion during the stance to swing phase transition (A₂) for the young group (31.3°) was about twice ( p < 0.05) that of the elderly (16.9°). Reduced knee extension range of motion suggests that the elderly favoured a flexed-knee gait to assist in weight acceptance. Reduced dorsiflexion by the elderly in the swing phase implies greater risk of toe contact with obstacles. Overall, the results suggest that joint angle measures at critical events/phases in the gait cycle provide a useful indication of age-related degeneration in the control of lower limb trajectories during unobstructed walking.     

An alternative extrinsic pathway of human blood coagulation

To study the interrelationships of the major human coagulation pathways, factor X activation in normal and various deficient human plasmas was evaluated when clotting was triggered by dilute rabbit or human thromboplastin. Various dilutions of thromboplastin were added to plasma samples containing 3H-labeled factor X, and the time course of factor X activation was determined. At a 1/250 dilution of rabbit brain thromboplastin the rate of factor X activation in factor VIII or factor IX deficient plasma was only 10% of the activation rate seen for normal or factor XI deficient plasma. Reconstitution of the deficient plasmas with factors VIII or IX, respectively, restored normal factor X activation. Similar results were obtained when various dilutions of human thromboplastin replaced the rabbit thromboplastin. From these experiments, it is inferred that normal activation of factor X in plasma due to dilute thromboplastin requires factors VII, IX and VIII. An alternative extrinsic pathway that involves factors VII, IX, and VIII may be a major physiologic extrinsic pathway, and this pathway may help to explain the clinical observations of bleeding diatheses in patients deficient in factors IX or VIII.     

Lack of rebound during intermittent transdermal treatment with glyceryl trinitrate in patients with stable angina on background beta blocker.

OBJECTIVE--To assess whether intermittent transdermal treatment with glyceryl trinitrate causes clinically significant rebound in patients maintained on beta blockers for stable angina pectoris. DESIGN--Serial treadmill exercise testing in a double blind, randomised, placebo controlled cross over trial. Baseline exercise testing was performed at 0900 and 1100 at visit 1. Transdermal glyceryl trinitrate patches releasing 15 mg/24 h were applied at 2200 the evening before visits 2 and 3, and exercise testing was performed at 0900 the next morning. The patch was removed and replaced with either an identical patch or matching placebo and exercise tests were repeated two hours later. The alternative treatment was given at visit 3. SETTING--Tertiary referral centre. PATIENTS--14 patients with stable angina pectoris maintained on beta blocker treatment alone. MAIN OUTCOME MEASURES--Time to angina, 1 mm ST segment depression, and total time, together with heart rate, systolic blood pressure, and rate-pressure product. RESULTS--Active treatment improved treadmill performance at 0900 and 1100. Time to angina, time to 1 mm ST segment depression, and total time fell significantly on placebo compared with the 0900 exercise test on active treatment, but were not significantly different to the baseline exercise test either. CONCLUSIONS--Intermittent transdermal treatment with glyceryl trinitrate is not associated with the rebound phenomenon in patients maintained on beta blockers for stable angina pectoris.     

Establishing and managing a periodontal biobank for research: the sharing of experience

Periodontal bio‐repositories, which allow banking of clinically validated human data and biological samples, provide an opportunity to derive biomarkers for periodontal diagnosis, prognosis and therapeutic activities which are expected to improve patient management. This article presents the establishing of the Malaysian Periodontal Database and Biobank System (MPDBS) which was initiated in 2011 with the aim to facilitate periodontal research. Partnerships were established with collaborating centres. Policies on specimen access, authorship and acknowledgement policies were agreed upon by all participating centres before the initiation of the periodontal biobank. Ethical approval for the collection of samples and data were obtained from institutional ethics review boards. A broad‐based approach for informed consent was used, which covered areas related to quality of life impacts, genetics and molecular aspects of periodontal disease. Sample collection and processing was performed using a standardized protocol. Biobanking resources such as equipment and freezers were shared with the Malaysian Oral Cancer Database and Tissue Bank System (MOCDTBS). In the development of the MPDBS, challenges that were previously faced by the MOCDTBS were considered. Future challenges in terms of ethical and legal issues will be faced when international collaborations necessitate the transportation of specimens across borders.     

Prognostic significance of transient ST segment changes after coronary artery bypass surgery: a long-term (4-10 year) follow up study.

OBJECTIVE--To assess the long-term (four to 10 years) prognostic significance of transient ST segment changes on ambulatory ST segment monitoring after coronary artery bypass grafting (CABG). PATIENTS AND METHODS--76 patients (67 men, nine women) underwent CABG between 1982 and 1984 (n = 31) and between 1987 and 1988 (n = 45) and at a mean age of 57. All underwent 48 hours of ambulatory ST segment monitoring at a mean of 19 weeks after surgery. The results were available for assessment. All general practitioners were contacted and patients' notes reviewed. Patients were contacted by telephone. Details were recorded of intervening events (acute myocardial infarction, unstable angina, need for further revascularisation, and deaths). Event free survival curves were produced for those with and without transient ST segment changes during routine postoperative ambulatory ST segment monitoring. RESULTS--During 3213 hours of monitoring after CABG, 21 (27.6%) of 76 patients had transient ST segment changes, of which 70% were silent. Over a mean 70 month follow up period, patients with such ischaemic changes were no more likely to have either an objective (myocardial infarction or cardiac death) or subjective (unstable angina or another revascularisation) event than those patients without ischaemic changes. This finding was the same in patients operated on between 1987 and 1988 and between 1982 and 1984. CONCLUSIONS--Although ambulatory ST segment monitoring is becoming increasingly popular in some countries as a routine investigation for ischaemia in various coronary subgroups, the findings of such an investigation, when performed after CABG, do not help to identify a subgroup more likely to have an adverse outcome during up to 10 years of follow up. There seems to be no reason to perform this investigation after surgery, and particularly to refer patients for reinvestigation because of the detection of predominantly silent ST segment changes of uncertain relevance.