Objective: We aimed to determine the frequency of all known forms of congenital muscular dystrophy (CMD) in a large Australasian cohort. Methods:We screened 101 patients with CMD with a combination of immunofluorescence, Western blotting, and DNA sequencing to identify disease-associated abnormalities in glycosylated ␣-dystroglycan, collagen VI, laminin ␣2, ␣7-integrin, and selenoprotein.Results: A total of 45% of the CMD cohort were assigned to an immunofluorescent subgroup based on their abnormal staining pattern. Abnormal staining for glycosylated ␣-dystroglycan was present in 25% of patients, and approximately half of these had reduced glycosylated ␣-dystroglycan by Western blot. Sequencing of the FKRP, fukutin, POMGnT1, and POMT1 genes in all patients with abnormal ␣-dystroglycan immunofluorescence identified mutations in one patient for each of these genes and two patients had mutations in POMT2. Twelve percent of patients had abnormalities in collagen VI immunofluorescence, and we identified disease-causing COL6 mutations in eight of nine patients in whom the genes were sequenced. Laminin ␣2 deficiency accounted for only 8% of CMD. ␣7-Integrin staining was absent in 12 of 45 patients studied, and ITGA7 gene mutations were excluded in all of these patients. LGMD2I ϭ limb-girdle muscular dystrophy type 2I; MDC1C ϭ congenital muscular dystrophy type 1C; MEB ϭ muscle-eyebrain disease; PVDF ϭ polyvinylidene fluoride; SSCP ϭ single strand conformational polymorphism; UCMD ϭ Ullrich congenital muscular dystrophy; WWS ϭ Walker-Warburg syndrome. Conclusions:

Osteonecrosis (ON) of the femoral head in childhood can lead to loss of femoral head architecture and subsequent deformity. When femoral head ON was surgically induced in 24 rats, zoledronic acid treatment and prophylaxis improved sphericity and maintenance of architecture at 6 weeks. This preliminary experiment supports the use of bisphosphonates in childhood ON. Introduction:We hypothesized that the bisphosphonate zoledronic acid could preserve femoral head structure while allowing bone repair. Materials and Methods: Osteonecrosis (ON) was surgically induced in the right femoral head of 24 female Wistar rats. The rats were randomized into three treatment groups and dosed subcutaneously with saline, zoledronic acid (0.1 mg/kg) at 1 and 4 weeks postoperation (ZA post), or zoledronic acid (0.1 mg/kg) given 2 weeks preoperation and at 1 and 4 weeks postoperation (ZA pre-post). After death at 6 weeks postoperation, undecalcified specimens were analyzed by DXA and standardized histomorphometric analysis. Results: Seventy-one percent of saline-operated femoral heads were aspherical (Mose score Ͼ 1), whereas only 13% and 0% of operated heads in the ZA-treated groups were aspherical (p Ͻ 0.05). DXA-measured bone mineral density in saline-treated femoral heads was reduced by 34% and 43% compared with the ZA-treated groups (p Ͻ 0.01). Histomorphometry showed decreases of 12% and 17% in bone volume (BV/TV) in saline groups compared with ZA post and ZA pre-post (p Ͻ 0.05), and a decrease in trabecular number (Tb.N) of 18% and 14% (p Ͻ 0.05), respectively. Bone formation rate (BFR) was increased by 56% in saline-treated operated heads over ZA post and was 4.8 times increased over the ZA pre-post group (p Ͻ 0.05). The differences in BV/TV and Tb.N in treated groups must therefore be caused by a reduction in bone turnover. Observational histology confirmed the retention of necrotic architecture in treated groups. Conclusions: Zoledronic acid treatment and prophylaxis preserved femoral head architecture after traumatic ON in this rat model at 6 weeks. These data indicate that, by conserving femoral head architecture, bone repair may occur in conjunction with improved femoral head shape.

International audienceSelenium is a trace element that is essential for human health and is incorporated into more than 25 human selenocysteine-containing (Sec-containing) proteins via unique Sec-insertion machinery that includes a specific, nuclear genome–encoded, transfer RNA (tRNA[Ser]Sec). Here, we have identified a human tRNA[Ser]Sec mutation in a proband who presented with a variety of symptoms, including abdominal pain, fatigue, muscle weakness, and low plasma levels of selenium. This mutation resulted in a marked reduction in expression of stress-related, but not housekeeping, selenoproteins. Evaluation of primary cells from the homozygous proband and a heterozygous parent indicated that the observed deficit in stress-related selenoprotein production is likely mediated by reduced expression and diminished 2′-O-methylribosylation at uridine 34 in mutant tRNA[Ser]Sec. Moreover, this methylribosylation defect was restored by cellular complementation with normal tRNA[Ser]Sec. This study identifies a tRNA mutation that selectively impairs synthesis of stress-related selenoproteins and demonstrates the importance of tRNA modification for normal selenoprotein synthesis

Objective-The collagen VI muscular dystrophies, Bethlem myopathy and Ullrich congenital muscular dystrophy, form a continuum of clinical phenotypes. Glycine mutations in the triple helix have been identified in both Bethlem and Ullrich congenital muscular dystrophy, but it is not known why they cause these different phenotypes.Methods-We studied eight new patients who presented with a spectrum of clinical severity, screened the three collagen VI messenger RNA for mutations, and examined collagen VI biosynthesis and the assembly pathway.Results-All eight patients had heterozygous glycine mutations toward the N-terminal end of the triple helix. The mutations produced two assembly phenotypes. In the first patient group, collagen VI dimers accumulated in the cell but not the medium, microfibril formation in the medium was moderately reduced, and the amount of collagen VI in the extracellular matrix was not significantly altered. The second group had more severe assembly defects: some secreted collagen VI tetramers