MYOC Mutations in Black South African Patients with Primary Open-angle Glaucoma: Genetic Testing and Cascade Screening

Background: Primary Open Angle Glaucoma (POAG) is an important cause of irreversible blindness in South Africa. Mutations in the MYOC gene are important in monogenic POAG. This study aimed to characterize potentially pathogenic MYOC mutations in this population.

Materials and Methods: Self-identified black South African POAG patients (215) and unaffected control participants (214) had ophthalmological examinations and DNA extraction. Potentially pathogenic MYOC variants were genotyped in the study population. Family members of participants with the mutations were screened for glaucoma clinically and for the mutations using Sanger sequencing.

Results: The following mutations were genotyped: Gly374Val (2 POAG patients), Lys500Arg (3 POAG patients) and Tyr453del (5 POAG patients). None of the relatives screened for Gly374Val had the mutation or POAG. The Lys500Arg mutation did not co-segregate with the disease in an affected family. The Tyr453del mutation co-segregated with the disease, but demonstrated incomplete penetrance. POAG patients with the Tyr453del mutation had adult-onset POAG with high intraocular pressures and advanced cupping.

Conclusions: Overall, 3.3% of black South Africans with POAG have a Gly374Val or Tyr453del MYOC mutation. The Tyr453del mutation is incompletely penetrant. That the mutation is necessary but insufficient introduces a counseling dilemma. Mutation screening can, however, identify high-risk individuals who can be monitored to detect early signs of the disease. The Gly374Val mutation is predicted to be damaging to MYOC. The Lys500Arg mutation is predicted to be benign and tolerated. This study has important implications for the management and counseling of black South African patients with POAG and their families.     

δ Subunit‐containing GABAA receptors are preferred targets for the centrally acting analgesic flupirtine

Background and Purpose

The K_v7 channel activator flupirtine is a clinical analgesic characterized as ‘selective neuronal potassium channel opener’. Flupirtine was found to exert comparable actions at GABA_A receptors and K_v7 channels in neurons of pain pathways, but not in hippocampus.

Experimental Approach

Expression patterns of GABA_A receptors were explored in immunoblots of rat dorsal root ganglia, dorsal horns and hippocampi using antibodies for 10 different subunits. Effects of flupirtine on recombinant and native GABA_A receptors were investigated in patch clamp experiments and compared with the actions on K_v7 channels.

Key Results

Immunoblots pointed towards α2, α3, β3 and γ2 subunits as targets, but in all γ2‐containing receptors the effects of flupirtine were alike: leftward shift of GABA concentration‐response curves and diminished maximal amplitudes. After replacement of γ2S by δ, flupirtine increased maximal amplitudes. Currents through α1β2δ receptors were more enhanced than those through K_v7 channels. In hippocampal neurons, flupirtine prolonged inhibitory postsynaptic currents, left miniature inhibitory postsynaptic currents (mIPSCs) unaltered and increased bicuculline‐sensitive tonic currents; penicillin abolished mIPSCs, but not tonic currents; concentration‐response curves for GABA‐induced currents were shifted to the left by flupirtine without changes in maximal amplitudes; in the presence of penicillin, maximal amplitudes were increased; GABA‐induced currents in the presence of penicillin were more sensitive towards flupirtine than K⁺ currents. In dorsal horn neurons, currents evoked by the δ‐preferring agonist THIP (gaboxadol) were more sensitive towards flupirtine than K⁺ currents.

Conclusions and Implications

Flupirtine prefers δ‐containing GABA_A receptors over γ‐containing ones and over K_v7 channels.

Abbreviations

aEPSC

autaptic EPSCs

aIPSC

autaptic IPSCs

BMI

bicuculline methiodide

CNQX

cyano‐2,3‐dihydroxi‐7‐nitroquinoxaline

DH

dorsal horn

DRG

dorsal root ganglion

mIPSCs

miniature IPSCs

THIP

4,5,6,7‐tetrahydroisoxazolo(5,4‐c)pyridin‐3‐ol) hydrochloride (= gaboxadol)

TTX

tetrodotoxin

     

Assessment and management of agitation in psychiatry: Expert consensus

Background Psychomotor agitation is associated with different psychiatric conditions and represents an important issue in psychiatry. Current recommendations on agitation in psychiatry are not univocal. Actually, an improper assessment and management may result in unnecessary coercive or sedative treatments. A thorough and balanced review plus an expert consensus can guide assessment and treatment decisions. Methods An expert task force iteratively developed consensus using the Delphi method. Initial survey items were based on systematic review of the literature. Subsequent surveys included new, re-worded or re-rated items. Results Out of 2175 papers assessing psychomotor agitation, 124 were included in the review. Each component was assigned a level of evidence. Integrating the evidence and the experience of the task force members, a consensus was reached on 22 statements on this topic. Conclusions Recommendations on the assessment of agitation emphasise the importance of identifying any possible medical cause. For its management, experts agreed in considering verbal de-escalation and environmental modification techniques as first choice, considering physical restraint as a last resort strategy. Regarding pharmacological treatment, the “ideal” medication should calm without over-sedate. Generally, oral or inhaled formulations should be preferred over i.m. routes in mildly agitated patients. Intravenous treatments should be avoided.     

Unusual presentations and intrafamilial phenotypic variability in infantile onset Alexander disease

Alexander disease is an hereditary leukodystrophy related to mutations of GFAP. Classically AxD was divided in infantile, juvenile, and adult subgroups. Recent data suggested considering only two subtypes: type I (infantile onset with lesions extending to the cerebral hemispheres); type II (adult onset with primary involvement of subtentorial structures). We report two related and one unrelated patients presenting with a peculiar association of clinical and neuroradiological features. GFAP analysis disclosed the presence of one novel and two previously reported mutations. Our patients underline the importance of considering AxD in patients with bulbar symptoms and autonomic dysfunction even if MRI shows only posterior fossa abnormalities, supporting the hypothesis of a third type of AxD sharing features of both type I and type II. The evidence of an intrafamilial phenotypic variability suggests the possible role of still unknown factors influencing the effect of GFAP mutation and determining the phenotype.     

Prognostic value of coronary blood flow velocity and myocardial perfusion in intermediate coronary narrowings and multivessel disease

OBJECTIVES: This study aimed to investigate the roles of intracoronary derived coronary flow velocity reserve (CFVR) and myocardial perfusion scintigraphy (single photon emission computed tomography, or SPECT) for management of an intermediate lesion in patients with multivessel coronary artery disease. BACKGROUND: Evaluation of the functional significance of intermediate coronary narrowings (40% to 70% diameter stenosis) is important for clinical decision making and risk stratification. METHODS: In a prospective, multicenter study, SPECT was performed in 191 patients with stable angina and multivessel disease and scheduled for angioplasty (percutaneous transluminal coronary angioplasty, or PTCA) of a severe coronary narrowing. Coronary flow velocity reserve was determined selectively distal to an intermediate lesion in another artery using a Doppler guidewire. Percutaneous transluminal coronary angioplasty of the intermediate lesion was deferred when SPECT was negative or CFVR greater-than-or-equal 2.0. Patients were followed for one year to document major cardiac events (death, infarction, revascularization), related to the intermediate lesion. RESULTS: Reversible perfusion defects were documented in the area of the intermediate lesion in 30 (16%) patients; CFVR was positive in 46 (24%) patients. Percutaneous transluminal coronary angioplasty of the intermediate lesion was deferred in 182 patients. During follow-up, 19 events occurred (3 myocardial infarctions, 16 revascularizations). Coronary flow velocity reserve was a more accurate predictor of cardiac events than was SPECT; relative risk: CFVR 3.9 (1.7 to 9.1), p < 0.05; SPECT 0.5 (0.1 to 3.2), p = NS. Multivariate analysis revealed CFVR as the only significant predictor for cardiac events.CONCLUSIONS: Deferral of PTCA of intermediate lesions in multivessel disease is safe when CFVR greater-than-or-equal 2.0 (event rate 6%). This selective evaluation of coronary lesion severity during cardiac catheterization allows a more accurate risk stratification than does SPECT, which is important for clinical decision making in this patient cohort.