Muscle MRI characteristic pattern for late-onset TK2 deficiency diagnosis

Journal of Neurology - TK2 deficiency (TK2d) is a rare mitochondrial disorder that manifests predominantly as a progressive myopathy with a broad spectrum of severity and age of onset. The rate of...     

X-linked Emery-Dreifuss muscular dystrophy and vacuoles: an immunohistochemical characterization

We report a striking abundance of rimmed vacuoles in two brothers with X-linked Emery-Dreifuss muscular dystrophy (X-EDMD) confirmed by the absence of emerin at the muscular nuclear envelope and by genetic analysis showing a new 2-bp deletion in exon 6 of the STA gene at the Xq28 region. Immunohistochemical analysis of the vacuoles revealed expression of dystrophin but not of merosin in the sarcolemma of rimmed vacuoles and absence of amyloid and membrane attack complex (MAC) deposition either in vacuoles or muscle fibers. The presence of rimmed vacuoles can be a histopathological finding in X-EDMD, and the diagnosis should not be excluded in clinically well-defined EDMD patients because of this finding.     

Genetics of the Charcot‐Marie‐Tooth disease in the Spanish Gypsy population: the hereditary motor and sensory neuropathy‐Russe in depth

Four private mutations responsible for three forms demyelinating of Charcot‐Marie‐Tooth (CMT) or hereditary motor and sensory neuropathy (HMSN) have been associated with the Gypsy population: the NDRG1 p.R148X in CMT type 4D (CMT4D/HMSN‐Lom); p.C737_P738delinsX and p.R1109X mutations in the SH3TC2 gene (CMT4C); and a G>C change in a novel alternative untranslated exon in the HK1 gene causative of CMT4G (CMT4G/HMSN‐Russe). Here we address the findings of a genetic study of 29 Gypsy Spanish families with autosomal recessive demyelinating CMT. The most frequent form is CMT4C (57.14%), followed by HMSN‐Russe (25%) and HMSN‐Lom (17.86%). The relevant frequency of HMSN‐Russe has allowed us to investigate in depth the genetics and the associated clinical symptoms of this CMT form. HMSN‐Russe probands share the same haplotype confirming that the HK1 g.9712G>C is a founder mutation, which arrived in Spain around the end of the 18th century. The clinical picture of HMSN‐Russe is a progressive CMT disorder leading to severe weakness of the lower limbs and prominent distal sensory loss. Motor nerve conduction velocity was in the demyelinating or intermediate range.     

Clinical and myopathological evaluation of early- and late-onset subtypes of myofibrillar myopathy

Myofibrillar myopathies (MFM) are a group of disorders associated with mutations in DES, CRYAB, MYOT, ZASP, FLNC, or BAG3 genes and characterized by disintegration of myofibrils and accumulation of degradation products into intracellular inclusions. We retrospectively evaluated 53 MFM patients from 35 Spanish families. Studies included neurologic exam, muscle imaging, light and electron microscopic analysis of muscle biopsy, respiratory function testing and cardiologic work-up. Search for pathogenic mutations was accomplished by sequencing of coding regions of the six genes known to cause MFM. Mutations in MYOT were the predominant cause of MFM in Spain affecting 18 of 35 families, followed by DES in 11 and ZASP in 3; in 3 families the cause of MFM remains undetermined. Comparative analysis of DES, MYOT and ZASP associated phenotypes demonstrates substantial phenotypic distinctions that should be considered in studies of disease pathogenesis, for optimization of subtype-specific treatments and management, and directing molecular analysis.     

Occurrence of cleft-palate and alteration of Tgf-β(3) expression and the mechanisms leading to palatal fusion in mice following dietary folic-acid deficiency

Folic acid (FA) is essential for numerous bodily functions. Its decrease during pregnancy has been associated with an increased risk of congenital malformations in the progeny. The relationship between FA deficiency and the appearance of cleft palate (CP) is controversial, and little information exists on a possible effect of FA on palate development. We investigated the effect of a 2-8 weeks' induced FA deficiency in female mice on the development of CP in their progeny as well as the mechanisms leading to palatal fusion, i.e. cell proliferation, cell death, and palatal-shelf adhesion and fusion. We showed that an 8 weeks' maternal FA deficiency caused complete CP in the fetuses although a 2 weeks' maternal FA deficiency was enough to alter all the mechanisms analyzed. Since transforming growth factor-β(3) (TGF-β(3)) is crucial for palatal fusion and since most of the mechanisms impaired by FA deficiency were also observed in the palates of Tgf-β(3)null mutant mice, we investigated the presence of TGF-β(3) mRNA, its protein and phospho-SMAD2 in FA-deficient (FAD) mouse palates. Our results evidenced a large reduction in Tgf-β(3) expression in palates of embryos of dams fed an FAD diet for 8 weeks; Tgf-β(3) expression was less reduced in palates of embryos of dams fed an FAD diet for 2 weeks. Addition of TGF-β(3) to palatal-shelf cultures of embryos of dams fed an FAD diet for 2 weeks normalized all the altered mechanisms. Thus, an insufficient folate status may be a risk factor for the development of CP in mice, and exogenous TGF-β(3) compensates this deficit in vitro.