30 years hids-Travels between bedside and bench

Increased core body temperature exacerbates defective protein prenylation in mouse models of mevalonate kinase deficiency

Mevalonate kinase deficiency (MKD) is characterized by recurrent fevers and flares of systemic inflammation, caused by biallelic loss-of-function mutations in MVK. The underlying disease mechanisms and triggers of inflammatory flares are poorly understood because of the lack of in vivo models. We describe genetically modified mice bearing the hypomorphic mutation p.Val377Ile (the commonest variant in patients with MKD) and amorphic, frameshift mutations in Mvk. Compound heterozygous mice recapitulated the characteristic biochemical phenotype of MKD, with increased plasma mevalonic acid and clear buildup of unprenylated GTPases in PBMCs, splenocytes, and bone marrow. The inflammatory response to LPS was enhanced in compound heterozygous mice and treatment with the NLRP3 inflammasome inhibitor MCC950 prevented the elevation of circulating IL-1β, thus identifying a potential inflammasome target for future therapeutic approaches. Furthermore, lines of mice with a range of deficiencies in mevalonate kinase and abnormal prenylation mirrored the genotype-phenotype relationship in human MKD. Importantly, these mice allowed the determination of a threshold level of residual enzyme activity, below which protein prenylation is impaired. Elevated temperature dramatically but reversibly exacerbated the deficit in the mevalonate pathway and the defective prenylation in vitro and in vivo, highlighting increased body temperature as a likely trigger of inflammatory flares.

The influence of sex and biological maturation on the sudomotor response to exercise-heat stress: Are girls disadvantaged?

Both adult females and children have been reported to have a lower sweating capacity and thus reduced evaporative heat loss potential which may increase their susceptibility to exertional hyperthermia in the heat. Compared to males, females have a lower maximal sweat rate and thus a theoretically lower maximum skin wettedness, due to a lower sweat output per gland. Similarly, children have been suggested to be disadvantaged in high ambient temperatures due to a lower sweat production and therefore reduced evaporative capacity, despite modifications of heat transfer due to physical attributes and possible evaporative efficiency. The reported reductions in sudomotor activity of females and children suggests a lower sweating capacity in girls. However, due to the complexities of isolating sex and maturation from the confounding effects of morphological differences (e.g., body surface area-to-mass ratio) and metabolic heat production, limited evidence exists supporting whether children and, more specifically, girls are at a thermoregulatory disadvantage. Furthermore, a limited number of child-adult comparison studies involve females and very few studies have directly compared regional and whole-body sudomotor activity between boys and girls. This mini review highlights the exercise-induced sudomotor response of females and children, summarises previous research investigating the sudomotor response to exercise in girls and suggests important areas for further research.

Spectrum of clinical features and genetic variants in mevalonate kinase (MVK) gene of South Indian families suffering from Hyperimmunoglobulin D Syndrome

Hyper-IgD syndrome (HIDS, OMIM #260920) is a rare autosomal recessive autoinflammatory disorder caused by pathogenic variants in the mevalonate kinase (MVK) gene. HIDS has an incidence of 1:50,000 to 1:5,000, and is thought to be prevalent mainly in northern Europe. Here, we report a case series of HIDS from India, which includes ten patients from six families who presented with a wide spectrum of clinical features such as recurrent fever, oral ulcers, rash, arthritis, recurrent diarrhea, hepatosplenomegaly, and high immunoglobulin levels. Using whole exome sequencing (WES) and/or Sanger capillary sequencing, we identified five distinct genetic variants in the MVK gene from nine patients belonging to six families. The variants were classified as pathogenic or likely pathogenic as per the American College of Medical Genetics and Genomics and the Association for Molecular Pathology (ACMG-AMP) guidelines for annotation of sequence variants. Over 70% of patients in the present study had two recurrent mutations in MVK gene i.e. a nonsynonymous variant p.V377I, popularly known as the ‘Dutch mutation’, along with a splicing variant c.226+2delT in a compound heterozygous form. Identity by descent analysis in two patients with the recurrent variants identified a 6.7 MB long haplotype suggesting a founder effect in the South Indian population. Our analysis suggests that a limited number of variants account for the majority of the patients with HIDS in South India. This has implications in clinical diagnosis, as well as in the development of cost-effective approaches for genetic diagnosis and screening. To our best knowledge, this is the first and most comprehensive case series of clinically and genetically characterized patients with HIDS from India.

The cock, the Academy, and the best scientific journal in the world

The reader is invited to travel to Ancient Greece, contemporary Brazil, and other places in a fantasy search for the best scientific journal. This whimsical search does not rely on the impact factor, the most popular tool used in real life for finding good journals. Instead, it takes advantage of the so-called authority factor, a recently proposed alternative to the impact factor. The authority factor of a particular journal is the mean h-index (Hirsch's index) of the most suitable group of this journal's editors. Having no connection to any major function of scientific journals, and also being arbitrary (which group of editors to select?), this factor is poorly suited for any technical analysis, but it seems to work well for "small-talk" editorials and self-promotion by complacent editors. Interestingly, the highest authority factor we could find belongs to the journal Temperature. This claim, however, should not be taken too seriously.