Gnathodiaphyseal dysplasia: Severe atypical presentation with novel heterozygous mutation of the anoctamin gene (ANO5).
ABSTRACT: Gnathodiaphyseal dysplasia (GDD; OMIM #166260) is an ultra-rare autosomal dominant disorder caused by heterozygous mutation in the anoctamin 5 (ANO5) gene and features fibro-osseous lesions of the jawbones, bone fragility with recurrent fractures, and bowing/sclerosis of tubular bones. The physiologic role of ANO5 is unknown. We report a 5-year-old boy with a seemingly atypical and especially severe presentation of GDD and unique ANO5 mutation. Severe osteopenia was associated with prenatal femoral fractures, recurrent postnatal fractures, and progressive bilateral enlargement of his maxilla and mandible beginning at ~2months-of-age that interfered with feeding and speech and required four debulking operations. Histopathological analysis revealed benign fibro-osseous lesions resembling cemento-ossifying fibromas of the jaw without psammomatoid bodies. A novel, de novo, heterozygous, missense mutation was identified in exon 15 of ANO5 (c.1553G>A; p.Gly518Glu). Our findings broaden the phenotypic and molecular spectra of GDD. Fractures early in life with progressive facial swelling are key features. We assessed his response to a total of 7 pamidronate infusions commencing at age 15months. Additional reports must further elucidate the phenotype, explore any genotype-phenotype correlation, and evaluate treatments.
Project description:Mutations in the gene ANO5, encoding for the transmembrane protein Anoctamin 5 (Ano5), have been identified to cause gnathodiaphyseal dysplasia (GDD) in humans, a skeletal disorder characterized by sclerosis of tubular bones, increased fracture risk and fibro-osseous lesions of the jawbones. To better understand the pathomechanism of GDD we have generated via Crispr/CAS9 gene editing a mouse model harboring the murine equivalent (Ano5 p.T491F) of a GDD-causing ANO5 mutation identified in a previously reported patient. Skeletal phenotyping by contact radiography, ?CT and undecalcified histomorphometry was performed in male mice, heterozygous and homozygous for the mutation, at the ages of 12 and 24 weeks. These mice did not display alterations of skeletal microarchitecture or mandible morphology. The results were confirmed in female mice and animals derived from a second, independent clone. Finally, no skeletal phenotype was observed in mice lacking ~40% of their Ano5 gene due to a frameshift mutation. Therefore, our results indicate that Ano5 is dispensable for bone homeostasis in mice, at least under unchallenged conditions, and that these animals may not present the most adequate model to study the physiological role of Anoctamin 5.
Project description:Gnathodiaphyseal dysplasia (GDD; MIM#166260) is an autosomal dominant syndrome with characteristic cemento-osseous lesions of jawbones, bone fragility, and diaphyseal sclerosis of tubular bones. To date, only five mutations in the proposed calcium-activated chloride channel ANO5/TMEM16E gene have been identified. In this study, we describe two families and two singular patients with three new mutations. One Caucasian family with seven affected members exhibited frequent bone fractures and florid osseous dysplasia (p.Cys356Tyr), while one Chinese family with two affected members suffered from cementoma and purulent osteomyelitis (p.Cys360Tyr). In addition, two different novel mutations (p.Gly518Glu and p.Arg215Gly) were identified in sporadic patients without family history. In vitro studies overexpressing GDD mutations (p.Cys356Tyr and p.Cys360Tyr) showed significantly reduced ANO5 protein. It appears that all GDD mutations known so far locate in an extracellular domain following the first transmembrane domain or in the 4th putative transmembrane domain. Both wild-type and mutant ANO5 protein localize to the endoplasmic reticulum. After Ano5 gene knock-down with shRNA in MC3T3-E1 osteoblast precursors we saw elevated expression of osteoblast-related genes such as Col1a1, osteocalcin, osterix and Runx2 as well as increased mineral nodule formation in differentiating cells. Our data suggest that ANO5 plays a role in osteoblast differentiation.
Project description:Gnathodiaphyseal dysplasia (GDD) is a rare autosomal dominant disorder characterized by florid osseous dysplasia of the jaws, bone fragility, and diaphyseal cortical thickening and bowing of long bones. We present a family with previously undiagnosed GDD. The disorder was identified by the characteristic gnathic and skeletal manifestations in the father. Clinical and radiologic examination of the patient's son also revealed the characteristic features of GDD. Gene sequencing revealed a novel mutation (c. 1067 G>A, p. Cys356 Tyr) in the ANO5 gene, which is causative for GDD. This mutation was predicted to be detrimental by computational analyses and by structural modeling of the protein. The implications for recognition and management of this disease are discussed.
Project description:Gnathodiaphyseal dysplasia (GDD) is an autosomal dominant syndrome characterized by frequent bone fractures at a young age, bowing of tubular bones and cemento-osseus lesions of the jawbones. Anoctamin 5 (ANO5) belongs to the anoctamin protein family that includes calcium-activated chloride channels. However, recent data together with our own experiments reported here add weight to the hypothesis that ANO5 may not function as calcium-activated chloride channel. By sequencing the entire ANO5 gene coding region and untranslated regions in a large Italian GDD family, we found a novel missense mutation causing the p.Thr513Ile substitution. The mutation segregates with the disease in the family and has never been described in any database as a polymorphism. To date, only two mutations on the same cysteine residue at position 356 of ANO5 amino-acid sequence have been described in GDD families. As ANO5 has also been found to be mutated in two different forms of muscular dystrophy, the finding of this third mutation in GDD adds clues to the role of ANO5 in these disorders.
Project description:Mutations in the human TMEM16E (ANO5) gene are associated both with the bone disease gnathodiaphyseal dysplasia (GDD; OMIM: 166260) and muscle dystrophies (OMIM: 611307, 613319). However, the physiological function of TMEM16E has remained unclear. We show here that human TMEM16E, when overexpressed in mammalian cell lines, displayed partial plasma membrane localization and gave rise to phospholipid scrambling (PLS) as well as non-selective ionic currents with slow time-dependent activation at highly depolarized membrane potentials. While the activity of wild-type TMEM16E depended on elevated cytosolic Ca2+ levels, a mutant form carrying the GDD-causing T513I substitution showed PLS and large time-dependent ion currents even at low cytosolic Ca2+ concentrations. Contrarily, mutation of the homologous position in the Ca2+-activated Cl- channel TMEM16B paralog hardly affected its function. In summary, these data provide the first direct demonstration of Ca2+-dependent PLS activity for TMEM16E and suggest a gain-of-function phenotype related to a GDD mutation.
Project description:Gnathodiaphyseal dysplasia (GDD) is a rare skeletal syndrome characterized by bone fragility, sclerosis of tubular bones, and cemento-osseous lesions of the jawbone. By linkage analysis of a large Japanese family with GDD, we previously mapped the GDD locus to chromosome 11p14.3-15.1. In the critical region determined by recombination mapping, we identified a novel gene (GDD1) that encodes a 913-amino-acid protein containing eight putative transmembrane-spanning domains. Two missense mutations (C356R and C356G) of GDD1 were identified in the two families with GDD (the original Japanese family and a new African American family), and both missense mutations occur at the cysteine residue at amino acid 356, which is evolutionarily conserved among human, mouse, zebrafish, fruit fly, and mosquito. Cellular localization to the endoplasmic reticulum suggests a role for GDD1 in the regulation of intracellular calcium homeostasis.
Project description:Mutations in ANO5 cause several human diseases including gnathodiaphyseal dysplasia 1 (GDD1), limb-girdle muscular dystrophy 2L (LGMD2L), and Miyoshi myopathy 3 (MMD3). Previous work showed that complete genetic disruption of Ano5 in mice did not recapitulate human muscular dystrophy, while residual expression of mutant Ano5 in a gene trapped mouse developed muscular dystrophy with defective membrane repair. This suggests that truncated Ano5 expression may be pathogenic. Here, we screened a panel of commercial anti-Ano5 antibodies using a recombinant adenovirus expressing human Ano5 with FLAG and YFP at the N- and C-terminus, respectively. The monoclonal antibody (mAb) N421A/85 was found to specifically detect human Ano5 by immunoblotting and immunofluorescence staining. The antigen epitope was mapped to a region of 28 residues within the N-terminus. Immunofluorescence staining of muscle cryosections from healthy control subjects showed that Ano5 is localized at the sarcoplasmic reticulum. The muscle biopsy from a LGMD2L patient homozygous for the c.191dupA mutation showed no Ano5 signal, confirming the specificity of the N421A/85 antibody. Surprisingly, strong Ano5 signal was detected in a patient with compound heterozygous mutations (c.191dupA and a novel splice donor site variant c.363?+?4A?>?G at the exon 6-intron 6 junction). Interestingly, insertion of the mutant intron 6, but not the wild-type intron 6, into human ANO5 cDNA resulted in a major transcript that carried the first 158-bp of intron 6. Transfection of the construct encoding the first 121 amino acids into C2C12 cells resulted in protein aggregate formation, suggesting that aggregate-forming Ano5 peptide may contribute to the pathogenesis of muscular dystrophy.
Project description:Lateral patellar dislocations can damage the medial patella femoral ligament. Nonoperative care is preferred but some tears may require a surgical intervention. Patella fractures are considered a risk factor after surgery. The technique described in this Technical Note avoids any bone tunnel drilling, which may eliminate the possibility of a patella fracture. The surgical procedure uses periosteal fibro-osseous tunnels to a double-limbed gracilis graft to reconstruct the upper and lower borders as conventionally used for medial patella femoral ligament reconstruction. Once the graft is tensioned, it is sutured to the periosteal fibro-osseous tunnel with 2 sutures on the medial side and at least 1 suture on the lateral side of each periosteal fibro-osseous sleeve. Each of the 2 periosteal fibro-osseous tunnels has 3 to 4 sutures securing the graft. After surgery, the patients complete 5 phases of rehabilitation to reduce swelling and to regain their strength and range of motion.
Project description:LGMD2L is a subtype of limb-girdle muscular dystrophy (LGMD), caused by recessive mutations in ANO5, encoding anoctamin-5 (ANO5). We present the analysis of five patients with skeletal muscle weakness for whom heterozygous mutations within ANO5 were identified by whole exome sequencing (WES). Patients varied in the age of the disease onset (from 22 to 38 years) and severity of the morphological and clinical phenotypes. Out of the nine detected mutations one was novel (missense p.Lys132Met, accompanied by p.His841Asp) and one was not yet characterized in the literature (nonsense, p.Trp401Ter, accompanied by p.Asp81Gly). The p.Asp81Gly mutation was also identified in another patient carrying a p.Arg758Cys mutation as well. Also, a c.191dupA frameshift (p.Asn64LysfsTer15), the first described and common mutation was identified. Mutations were predicted by in silico tools to have damaging effects and are likely pathogenic according to criteria of the American College of Medical Genetics and Genomics (ACMG). Indeed, molecular modeling of mutations revealed substantial changes in ANO5 conformation that could affect the protein structure and function. In addition, variants in other genes associated with muscle pathology were identified, possibly affecting the disease progress. The presented data indicate that the identified ANO5 mutations contribute to the observed muscle pathology and broaden the genetic spectrum of LGMD myopathies.
Project description:OBJECTIVE:ANO5-related myopathy is an important cause of limb-girdle muscular dystrophy (LGMD) and hyperCKemia. The main descriptions have emerged from European cohorts, and the burden of the disease worldwide is unclear. We provide a detailed characterization of a large Brazilian cohort of ANO5 patients. METHODS:A national cross-sectional study was conducted to describe clinical, histopathological, radiological, and molecular features of patients carrying recessive variants in ANO5. Correlation of clinical and genetic characteristics with different phenotypes was studied. RESULTS:Thirty-seven patients from 34 nonrelated families with recessive mutations of ANO5 were identified. The most common phenotype was LGMD, observed in 25 (67.5%) patients, followed by pseudometabolic presentation in 7 (18.9%) patients, isolated asymptomatic hyperCKemia in 4 (10.8%) patients, and distal myopathy in a single patient. Nine patients presented axial involvement, including one patient with isolated axial weakness. The most affected muscles according to MRI were the semimembranosus and gastrocnemius, but paraspinal and abdominal muscles, when studied, were involved in most patients. Fourteen variants in ANO5 were identified, and the c.191dupA was present in 19 (56%) families. Sex, years of disease, and the presence of loss-of-function variants were not associated with specific phenotypes. INTERPRETATION:We present the largest series of anoctaminopathy outside Europe. The most common European founder mutation c.191dupA was very frequent in our population. Gender, disease duration, and genotype did not determine the phenotype.