0000000000067534
AUTHOR
Nigel G. Laing
Genotype-phenotype correlations in nemaline myopathy caused by mutations in the genes for nebulin and skeletal muscle alpha-actin.
We present comparisons of the clinical pictures in a series of 60 patients with nemaline myopathy in whom mutations had been identified in the genes for nebulin or skeletal muscle alpha-actin. In the patients with nebulin mutations, the typical form of nemaline myopathy predominated, while severe, mild or intermediate forms were less frequent. Autosomal recessive inheritance had been verified or appeared likely in all nebulin cases. In the patients with actin mutations, the severe form of nemaline myopathy was the most common, but some had the mild or typical form, and a few showed other associated features such as intranuclear rods or actin accumulation. Most cases were sporadic, but in ad…
Fetal akinesia caused by a novel actin filament aggregate myopathy skeletal muscle actin gene (ACTA1) mutation.
We report a female newborn, diagnosed with fetal akinesia in utero, who died one hour after birth. Post-mortem muscle biopsy demonstrated actin-filament myopathy based on immunolabelling for sarcomeric actin, and large areas of filaments, without rod formation, ultrastructurally. Analysis of DNA extracted from the muscle disclosed a novel de novo heterozygous c.44G>A, GGC>GAC, 'p.Gly15Asp' mutation in the ACTA1 gene. Analysis of the location of the mutated amino-acid in the actin molecule suggests the mutation most likely causes abnormal nucleotide binding, and consequent pathological actin polymerization. This case emphasizes the association of fetal akinesia with actin-filament myopathy.
A Roma founder BIN1 mutation causes a novel phenotype of centronuclear myopathy with rigid spine
ObjectiveTo describe a large series of BIN1 patients, in which a novel founder mutation in the Roma population of southern Spain has been identified.MethodsPatients diagnosed with centronuclear myopathy (CNM) at 5 major reference centers for neuromuscular disease in Spain (n = 53) were screened for BIN1 mutations. Clinical, histologic, radiologic, and genetic features were analyzed.ResultsEighteen patients from 13 families carried the p.Arg234Cys variant; 16 of them were homozygous for it and 2 had compound heterozygous p.Arg234Cys/p.Arg145Cys mutations. Both BIN1 variants have only been identified in Roma, causing 100% of CNM in this ethnic group in our cohort. The haplotype analysis confi…
Actin-related myopathy without any missense mutation in the ACTA1 gene.
Actinopathies are defined by missense mutations in the ACTA1 gene coding for sarcomeric actin, of which some 70 families have, so far, been identified. Often, but not always, muscle fibers carry large patches of actin filaments. Many such patients also have nemaline myopathy, qualifying actinopathies as a subgroup of nemaline myopathies. This article concerns a then newborn, now 21/2-year-old boy, the first and single child of nonconsanguineous parents, who was born floppy, requiring immediate postnatal assisted ventilation. A quadriceps muscle biopsy revealed large patches of thin myofilaments reacting at light and electron microscopic levels with antibodies against actin but only a few s…
Intranuclear nemaline rod myopathy
The clinical, pathologic, and genetic findings of a boy with intranuclear nemaline rod myopathy are described. Serial muscle biopsies revealed myocyte nuclei containing inclusions that were immunoreactive for α-actinin and increased with age. Genetic analysis revealed a Val163Leu ACTA1 mutation previously associated with nemaline rod myopathy. Although initially delayed, he has reached all milestones and remains stable. These findings suggest intranuclear rods may increase with time and do not necessarily imply a poor prognosis. Muscle Nerve, 2006
Mutations in the skeletal muscle alpha-actin gene in patients with actin myopathy and nemaline myopathy
Muscle contraction results from the force generated between the thin filament protein actin and the thick filament protein myosin, which causes the thick and thin muscle filaments to slide past each other. There are skeletal muscle, cardiac muscle, smooth muscle and non-muscle isoforms of both actin and myosin. Inherited diseases in humans have been associated with defects in cardiac actin (dilated cardiomyopathy and hypertrophic cardiomyopathy), cardiac myosin (hypertrophic cardiomyopathy) and non-muscle myosin (deafness). Here we report that mutations in the human skeletal muscle alpha-actin gene (ACTA1) are associated with two different muscle diseases, 'congenital myopathy with excess o…
Actinopathies and Myosinopathies
The currently recognized two forms of "anabolic" protein aggregate myopathies, that is, defects in development, maturation and final formation of respective actin and myosin filaments encompass actinopathies and myosinopathies. The former are marked by mutations in the ACTA1 gene, largely of the de novo type. Aggregates of actin filaments are deposited within muscle fibers. Early clinical onset is often congenital; most patients run a rapidly progressive course and die during their first 2 years of life. Myosinopathies or myosin storage myopathies also commence in childhood, but show a much more protracted course owing to mutations in the myosin heavy chain gene MYH7. Protein aggregation co…
Novel slow-skeletal myosin (MYH7) mutation in the original myosin storage myopathy kindred
Abstract Myosin storage myopathy (OMIM 608358), a congenital myopathy characterised by subsarcolemmal, hyaline-like accumulations of myosin in Type I muscle fibres, was first described by Cancilla and Colleagues in 1971 [Neurology 1971;21:579–585] in two siblings as ‘familial myopathy with probable lysis of myofibrils in type I muscle fibres'. Two mutations in the slow skeletal myosin heavy chain gene ( MYH7 ) have recently been associated with the disease in other families. We have identified a novel heterozygous Leu1793Pro mutation in MYH7 in DNA from paraffin sections of one of the original siblings. This historical molecular analysis confirms the original cases had myosin storage myopat…