A calibrated functional patch clamp assay to enhance clinical variant interpretation in KCNH2-related long QT syndrome

Purpose: Modern sequencing technologies have revolutionised our detection of gene variants. In most genes, including KCNH2, the majority of missense variants are currently classified as variants of uncertain significance (VUS). The aim of this study is to investigate the utility of an automated patch-clamp assay for aiding clinical variant classification in the KCNH2 gene. Methods: The assay was designed according to recommendations of the ClinGen sequence variant interpretation framework. Thirty-one control variants of known clinical significance (17 pathogenic/likely pathogenic, 14 benign/likely benign) were heterozygously expressed in Flp-In HEK293 cells. Variants were analysed for effects on current density and channel gating. A panel of 44 VUS was then assessed for reclassification. Results: All 17 pathogenic variant controls had reduced current density and 13/14 benign variant controls had normal current density, which enabled determination of normal and abnormal ranges for applying moderate or supporting evidence strength for variant classification. Inclusion of KCNH2 functional assay evidence enabled us to reclassify 6 out of 44 VUS as likely pathogenic. Conclusion: The high-throughput patch clamp assay can provide moderate strength evidence for clinical interpretation of clinical KCNH2 variants and demonstrates the value proposition for developing automated patch clamp assays for other ion channel genes.

Rapid-onset oral isotretinoin-induced acne fulminans without systemic symptoms in a male adolescent

Isotretinoin-induced acne fulminans without systemic symptoms (IIAF-WOSS) is an uncommon clinical variant of acne, not exhibiting systemic symptoms but with potentially severe skin lesions. Some authors believe that its occurrence is dose-dependent. Herein, we present the case of a sixteen-year-old boy with IIAF-WOSS, which developed two weeks after starting treatment with isotretinoin 0.6 mg/kg/day. The patient was successfully treated with a systemic steroid. IIAF-WOSS may cause significant disfiguring scarring, thus the physician needs to be aware of this condition, even early with low doses of isotretinoin.

APPRIS principal isoforms and MANE Select transcripts in clinical variant interpretation

Most coding genes are able to generate multiple alternatively spliced transcripts. Determining which of these transcript variants produces the main protein isoform, and which of a gene’s multiple splice variants are functionally important, is crucial in comparative genomics and essential for clinical variant interpretation.Here we show that the principal isoforms chosen by APPRIS and the MANE Select variants provide the best approximations of the main cellular protein isoforms. Principal isoforms are predicted from conservation and from protein features, and MANE transcripts are chosen from the consensus between teams of expert manual curators. APPRIS principal isoforms coincide in over 94% of coding genes with MANE Select transcripts and the two methods are particularly discriminating when they agree on the main splice variant. Where the two methods agree, the splice variants coincide with the main isoform detected in proteomics experiments in 98.2% of genes with multiple protein isoforms.We also find that almost all ClinVar pathogenic mutations map to MANE Select or APPRIS principal isoforms. Where APPRIS and MANE agree on the main isoform, 99.93% of validated pathogenic variants map to principal rather than alternative exons. MANE Plus Clinical transcripts cover most validated pathogenic mutations in alternative coding exons. TRIFID functional importance scores are particularly useful for distinguishing clinically important alternative isoforms: the highest scoring TRIFID isoforms are more than 300 times more likely to have validated pathogenic mutations.We find that APPRIS, MANE and TRIFID are important for determining the biological relevance of splice isoforms and should be an essential part of clinical variant interpretation.

The clinical case of successful combined treatment of refractory arterial hypertension. Case report

In recent years, there has been an increase of patients with arterial hypertension, one of the variants of which is refractory arterial hypertension. This unfavorable clinical variant of the course of hypertension worries clinicians, due to the higher risk of developing cardiovascular complications, realizing the need for a better control of blood pressure. The presented clinical case demonstrates the successful combined treatment of refractory hypertension using antihypertensive therapy and renal denervation.

Bullous Scabies: Clinical, Dermoscopic, and Pathologic Characteristics of 10 Patients

Bullous scabies (BS) is a rare atypical clinical variant of scabies and is easily confused with bullous disorders. The diagnosis of BS is always a challenge, and physicians often misdiagnose BS patients. Patients with BS admitted from 2012 to 2020 were enrolled in this study. The clinical, dermoscopic, and pathological characteristics of the patients were analyzed retrospectively. Ten patients with BS were enrolled in this study. Seven of the 10 patients were male. The bullae were most commonly found on the thighs and arms (80% of patients). Only 30% of patients (3/10) tested positive for mites and/or eggs by the initial skin scraping, but 100% (5/5) of the patients who received dermoscopy tested positive. Among these 10 patients, only five received a skin biopsy. Subepidermal (4/5) and intraepidermal (1/5) bullae with eosinophil and neutrophil infiltration were observed in five patients. Direct immunofluorescence (DIF) indicated linear deposition of IgG in the basement membrane zone in three patients. Physicians should consider the possibility of BS in patients with blisters, pruritus, and poor response to corticosteroids. Dermoscopy should be prioritized for the differential diagnosis of BS to exclude other bullous disorders. Finally, a biopsy should be performed on each patient with bullae.