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Protein aggregate myopathies can result from pathogenic variants in genes encoding protein chaperones. DNAJB4 is a cochaperone belonging to the heat shock protein-40 (HSP40) family and plays a vital role in cellular proteostasis. Recessive loss-of-function variants in DNAJB4 cause myopathy with early respiratory failure and spinal rigidity, presenting from infancy to adulthood. This study investigated the broader clinical and genetic spectrum of DNAJB4 myopathy. In this study, we performed whole-exome sequencing on seven patients with early respiratory failure of unknown genetic etiology. We identified five distinct pathogenic variants in DNAJB4 in five unrelated families of diverse ethnic backgrounds: three loss-of-function variants (c.547 C > T, p.R183*; c.775 C > T, p.R259*; an exon 2 deletion) and two missense variants (c.105G > C, p.K35N; c.181 A > G, p.R61G). All patients were homozygous. Most affected individuals exhibited early respiratory failure, and patients from three families had rigid spine syndrome with axial weakness in proportion to appendicular weakness. Additional symptoms included dysphagia, ankle contractures, scoliosis, neck stiffness, and cardiac dysfunction. Notably, J-domain missense variants were associated with a more severe phenotype, including an earlier age of onset and a higher mortality rate, suggesting a strong genotype‒phenotype correlation. Consistent with a loss of function, the nonsense variants presented decreased stability. In contrast, the missense variants exhibited normal or increased stability but behaved as loss-of-function variants in yeast complementation and TDP-43 disaggregation assays. Our findings suggest that DNAJB4 is an emerging cause of myopathy with rigid spine syndrome of variable age of onset and severity. This diagnosis should be considered in individuals presenting with suggestive symptoms, particularly if they exhibit neck stiffness during infancy or experience respiratory failure in adults without significant limb muscle weakness. Missense variants in the J domain may predict a more severe phenotype., (© 2024. The Author(s).)

Mallory-Denk bodies (MDBs) are hepatocellular cytoplasmic inclusions, which occur in certain chronic liver diseases, such as alcohol-related (ASH) and metabolic dysfunction-associated (MASH) steatohepatitis, copper toxicosis, some drug-induced liver disorders, chronic cholangiopathies, and liver tumors. Our study focused on the expression of the senescence markers p21 WAF1/cip1 and p16 INK4a in hepatocytes containing MDBs in steatohepatitis, chronic cholangiopathies with fibrosis or cirrhosis, Wilson's disease, and hepatocellular carcinomas. Cytoplasm and nuclei of MDB-containing hepatocytes as well as MDB inclusions, except those associated with carcinoma cells, were strongly p16-positive, p21-positive, as well as p21-negative nuclei in MDB-containing hepatocytes which were observed whereas MDBs were p21-negative. Expression of the senescence marker p16 suggests that MDB formation reflects an adaptive response to chronic stress resembling senescence with its consequences, i.e., expression of inflammation- and fibrosis-prone secretome. Thus, senescence can be regarded as "double-edged sword" since, on the one hand, it may be an attempt of cellular defense, but, on the other, also causes further and sustained damage by inducing inflammation and fibrosis related to the senescence-associated secretory phenotype and thus progression of chronic liver disease., (© 2024. The Author(s).)

LAMA2-related muscular dystrophy (LAMA2-MD) and SELENON(SEPN1)-related myopathy (SELENON-RM) are rare neuromuscular diseases caused by mutations in the LAMA2 and SELENON (SEPN1) gene, respectively. Systematic reviews on cardiac features in both neuromuscular diseases are lacking. This scoping review aims to elucidate the cardiac involvement in LAMA2-MD or SELENON-RM. Three electronic databases (PubMed, Embase and Cochrane) were searched. All studies, case reports and case series with information on cardiac features in LAMA2-MD or SELENON-RM patients were included. Study selection and data extraction were performed by two independent reviewers. 31 Articles on LAMA2-MD and 17 articles on SELENON-RM met the inclusion criteria, resulting in the inclusion of 131 LAMA2-MD and 192 SELENON-RM cases. In 41% of LAMA2-RM cases, a cardiac abnormality was present. Left ventricular systolic dysfunction and arrhythmia were most frequently described. In 15% of SELENON-RM cases, a cardiac abnormality was reported, of which pulmonary hypertension, including right ventricular dysfunction secondary to pulmonary failure, was most prevalent. We conclude that in LAMA2-MD primary left ventricular dysfunction and in SELENON-RM secondary right ventricular dysfunction are frequently reported. Optimal cardiorespiratory surveillance by screening of asymptomatic patients every two years with ECG, Holter and echocardiography is necessary for early detection and/or treatment of cardiac manifestations., Competing Interests: Declaration of Competing Interest All other authors declare that they have no competing interests. This work was supported by a grant from Stichting Spieren voor Spieren, Stichting Stofwisselkracht and Stichting Voor Sara, The Netherlands. The funders have no role in the collection, analysis and interpretation of data, in the writing of the report, and in the decision to submit the article for publication. Several authors of this publication are members of the Radboudumc Center of Expertise for neuromuscular disorders (Radboudumc-NMD), the Netherlands Neuromuscular Center (NL-NMD) and European Reference Network for rare neuromuscular diseases (EURO-NMD)., (Copyright © 2022. Published by Elsevier B.V.)