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Hereditary Multiple Osteochondromas
Published in Dongyou Liu, Handbook of Tumor Syndromes, 2020
Germline loss-of-function mutations (e.g., nonsense, frameshift, splice site, missense variants) in the EXT1 and EXT2 genes leading to premature terminations of the EXT proteins cause HS deficiency and subsequent cytoskeletal abnormalities (e.g., actin accumulation, excessive bundling by alpha-actinin, and abnormal presence of muscle-specific alpha-actin) [1].
Neurological and neuromuscular disorders
Published in Rachel U Sidwell, Mike A Thomson, Concise Paediatrics, 2020
Rachel U Sidwell, Mike A Thomson
Abnormal rod-shaped inclusions within muscle fibres (mostly α-actinin). Autosomal dominant or recessive. Variable penetrance of dominant form, with mildly affected individuals having poorly developed muscles only.
The locomotor system
Published in C. Simon Herrington, Muir's Textbook of Pathology, 2020
The largest tissue within the body, muscle, accounting for 40% of an average male's weight, is highly organized to contract, produce movement or stability, and do work. Skeletal muscle consists of long multinucleated syncytia formed by the fusion of columns of single cells. The cytoplasm contains bundles of myosin and actin filaments forming contractile myofibrils. The individual subunit is the sarcomere and these are arranged end to end to form muscle fibres. The parallel alignment of actin and myosin bundles gives a characteristic band-like appearance on light microscopy and alternating dark (A, anisotropic) and light (I, isotropic) bands are seen on electron microscopy. A variety of other proteins including α-actinin and dystrophin are found within muscle cells. The individual muscle fibre is surrounded by the endomysium. Fibres are bound into fascicles by the perimysium, whereas the muscle itself is sheathed by the epimysium.
ACTN3 R577X polymorphism related to sarcopenia and physical fitness in active older women
Published in Climacteric, 2021
C. Romero-Blanco, M. J. Artiga González, A. Gómez-Cabello, S. Vila-Maldonado, J. A. Casajús, I. Ara, S. Aznar
As well as the health benefits of physical activity in the elderly, investigating whether genetics determine better physical fitness or muscle mass8,9 is also of great interest. One of the most studied genetic polymorphisms has been ACTN3 R577X at position 1747 in exon 16, where an arginine turns into a codon stop due to the replacement of a cytosine by a thymine10. Homozygous XX people cannot produce the ACTN3 protein in the muscle, something estimated to take place in approximately 18% of the population11. ACTN3 is a structural protein and the predominant component of the Z areas of the sarcomere; α-actinin-3 deficiency in the general population seems to be connected to an age-related decrease of muscle mass and physical strength12.
ANGPTL3: a novel biomarker and promising therapeutic target
Published in Journal of Drug Targeting, 2019
Shuang Jiang, Guo-Hui Qiu, Neng Zhu, Zhe-Yu Hu, Duan-Fang Liao, Li Qin
Most importantly, ANGPTL3 interacts with podocyte-expressed integrin β3, and raise the expression of α-actinin-4, which may result in the cytoskeletal rearrangement of podocytes. ANGPTL3 significantly disturbs the normal expression of α-actinin-4 at both mRNA and protein level, which induces podocyte actin realignment [70]. α-actinin-4, an actin-modulating protein and downstream signal for integrin β3, can cross-link with F-actin to maintain the necessary polarity for actin bundle formation. Either the up-regulation or absence of α-actinin-4 in podocytes can lead to the development and progression of nephropathy [73].
PPARD CC and ACTN3 RR genotype prevalence among elite soccer players
Published in Science and Medicine in Football, 2020
Yoav Meckel, Alon Eliakim, Dan Nemet, Nir Levin, Sigal Ben-Zaken
Genetic variants among aerobic- and anaerobic-type athletes were previously demonstrated. The ACTN3 RR genotype was found to be significantly more prevalent among sprinters and jumpers (S/J) compared to long distance runners (LDR) and control non-athletes (Eynon et al. 2013; Papadimitriou et al. 2016). ACTN3 encodes for the synthesis of α-actinin-3 in skeletal-muscle fibers. This sarcomeric protein is necessary for powerful ‘explosive’ muscle contractions, and is associated with speed and other anaerobic-type performance qualities (Egorova et al. 2014). The prevalence of this genotype was also examined in team-sport athletes. The distribution of RR genotype was found to be significantly higher among soccer players than controls and endurance athletes(Santiago et al. 2008) and it seems to protect players from muscle injuries (Massidda et al. 2019) and eccentric muscle damage (Pimenta et al. 2012). Moreover, it was found that young soccer players who had higher frequencies of ACTN3 RR/RX genotypes presented better performance during jump and sprint tests (Dionísio et al. 2017). In line with this, Pimenta et al. (2013) examined 200 Brazilian professional soccer players and found that ACTN3/RR carriers exhibited better anaerobic performance results than XX carriers. Furthermore, the former scored higher in jump tests compared to both 577RX and 577XX carriers. In contrast to these findings, Coelho et al. (2016) did not find differences in physical performance between α-actinin-3 R577X genotypes in adult, U-20 and U-17 professional Brazilian first-division soccer players. In another study, team sport athletes showed a non-significant lower frequency of the 577RR genotype compared to the 577XX genotype than sprint/power athletes. The authors concluded that the ACTN3 R577X polymorphism was not associated with team-sport athletic status compared to endurance athletes and non-athletic controls (Massidda et al. 2015). Similar results were also found among a cohort from Poland, Russia and Spain (Eynon et al. 2014).