Antisense oligonucleotide therapeutic approach for Timothy syndrome

Timothy syndrome (TS) is a severe, multisystem disorder characterized by autism, epilepsy, long-QT syndrome and other neuropsychiatric conditions1. TS type 1 (TS1) is caused by a gain-of-function variant in the alternatively spliced and developmentally enriched CACNA1C exon 8A, as opposed to its counterpart exon 8. We previously uncovered several phenotypes in neurons derived from patients with TS1, including delayed channel inactivation, prolonged depolarization-induced calcium rise, impaired interneuron migration, activity-dependent dendrite retraction and an unanticipated persistent expression of exon 8A2-6. We reasoned that switching CACNA1C exon utilization from 8A to 8 would represent a potential therapeutic strategy. Here we developed antisense oligonucleotides (ASOs) to effectively decrease the inclusion of exon 8A in human cells both in vitro and, following transplantation, in vivo. We discovered that the ASO-mediated switch from exon 8A to 8 robustly rescued defects in patient-derived cortical organoids and migration in forebrain assembloids. Leveraging a transplantation platform previously developed7, we found that a single intrathecal ASO administration rescued calcium changes and in vivo dendrite retraction of patient neurons, suggesting that suppression of CACNA1C exon 8A expression is a potential treatment for TS1. Broadly, these experiments illustrate how a multilevel, in vivo and in vitro stem cell model-based approach can identify strategies to reverse disease-relevant neural pathophysiology.

Current updates on arrhythmia within Timothy syndrome: genetics, mechanisms and therapeutics

Timothy syndrome (TS), characterised by multiple system malfunction especially the prolonged corrected QT interval and synchronised appearance of hand/foot syndactyly, is an extremely rare disease affecting early life with devastating arrhythmia. In this work, firstly, the various mutations in causative gene CACNA1C encoding cardiac L-type voltage-gated calcium channel (LTCC), regard with the genetic pathogeny and nomenclature of TS are reviewed. Secondly, the expression profile and function of CACNA1C gene encoding Cav1.2 proteins, and its gain-of-function mutation in TS leading to multiple organ disease phenotypes especially arrhythmia are discussed. More importantly, we focus on the altered molecular mechanism underlying arrhythmia in TS, and discuss about how LTCC malfunction in TS can cause disorganised calcium handling with excessive intracellular calcium and its triggered dysregulated excitation-transcription coupling. In addition, current therapeutics for TS cardiac phenotypes including LTCC blockers, beta-adrenergic blocking agents, sodium channel blocker, multichannel inhibitors and pacemakers are summarised. Eventually, the research strategy using patient-specific induced pluripotent stem cells is recommended as one of the promising future directions for developing therapeutic approaches. This review updates our understanding on the research progress and future avenues to study the genetics and molecular mechanism underlying the pathogenesis of devastating arrhythmia within TS, and provides novel insights for developing therapeutic measures.

[Vismodegib for basal cell carcinoma: targeted therapy in case of locally advanced or metastasised disease]

The development of the hedgehog pathway inhibitor vismodegib provides a new treatment option for metastasised and locally advanced basal cell carcinoma in which surgical excision or radiotherapy is contraindicated. Only a fraction of patients with basal cell carcinoma are eligible for this therapy, but it is effective in the majority of those who do receive vismodegib. However, development of tumour resistance is quite common and adverse events frequently lead to discontinuation of therapy. Intermittent treatment or combination therapy could reduce the occurrence of tumour resistance and diminish toxicity. We present three patients who were successfully treated with vismodegib: a 73-year-old man with locally advanced basal cell carcinoma, an 82-year-old man with basal cell carcinoma that had metastasised to the lungs, and a 42-year-old man with Gorlin syndrome.

Iloprost administration in acrodermatitis of Hallopeau complicated by acquired toes syndactyly: a case report and review of the literature

OBJECTIVE

Acrodermatitis Continua of Hallopeau (ACH) is a variant of pustular psoriasis often very difficult to treat. Secondary syndactyly, also called "pseudosyndactyly", is rare and can be a complication of burns, dystrophic epidermolysis bullosa or trauma. If left untreated, joint complications and definitive functional impairments may occur.

CASE REPORT

We report a case of a 74-year-old man with acrodermatitis continua of Hallopeau involving the toes and complicated by syndactyly. ACH regression following Iloprost administration was also observed.

DISCUSSION

Published studies are mainly limited to case reports only, due to the rarity of the disease. Therefore, there are no clear-cut therapeutic management guidelines available for this chronic and sometimes debilitating disease. ACH is often recalcitrant to the available therapies. Topical and systemic treatments have been described in literature with no long-lasting results.

CONCLUSIONS

To our knowledge, this is the first report of foot syndactyly associated to ACH. In our patient, ACH symptoms regressed with Iloprost administration: this finding has never been previously described in literature. If confirmed by other clinical experiences, Iloprost could be a further therapeutic option in ACH.

Sclerostin and skeletal health

Sclerostin is a cysteine-knot glycoprotein product of the SOST gene, predominately expressed by osteocytes, that is a regulator of osteoblastic bone formation. When sclerostin binds to its low-density lipoprotein receptor-related proteins 5 and 6 on the cell membrane of osteoblasts, it inhibits canonical Wnt/β-catenin signaling and reduces osteoblastic bone formation. Sclerostin was first identified in the study of two rare autosomal recessive disorders, sclerosteosis and van Buchem disease, which are associated with absent or reduced levels of sclerostin. Although homozygote patients with these disorders have serious adverse clinical consequences due to excessive bone growth, heterozygote patients have a normal phenotype, high bone mass, and very low risk of fractures. This has led to the concept that downregulation of sclerostin might be effective in the treatment of osteoporosis. Several humanized monoclonal antibodies to sclerostin, including romosozumab and blosozumab, are now in clinical development. Preliminary data show that these agents result in a transient increase in bone formation markers, a sustained decrease in bone resorption markers, and a robust increase in bone mineral density. If any of these agents are found to reduce fracture risk with a favorable safety profile, it will expand the options for osteoanabolic therapy for patients at high risk for fractures.