Gnathodiaphyseal dysplasia

Gnathodiaphyseal dysplasia with a novel genetic variant in a large family from Iran

Background

Gnathodiaphyseal dysplasia (GDD) is an ultrarare autosomal dominant bone dysplasia characterized by cementoosseous lesions of the jawbones, bone fragility, frequent bone fractures at the young age, bowing of tubular bones, and diaphyseal sclerosis of long bones associated with generalized osteopenia. GDD is caused by point mutations in anoctamin‐5 (ANO5) on chromosome 11p14.3. For the past few years, next generation sequencing (NGS) technology has facilitated the discovery of causative variants in genetically heterogeneous diseases.

Methods

In this study, exome sequencing (ES) was performed using the DNA sample of the proband. Family histories and clinical information were collected through comprehensive medical examination and genetic counseling.

Results

ES results identified a heterozygous variant, NM_213599.3:c.1078T>C(p.Cys360Arg) in the ANO5 gene. Sanger sequencing was performed to confirm the detected pathogenic variant in DNA samples of the entire family (except deceased individuals), which segregated with the disease within the family. Finally, in silico analysis was applied to test the pathogenicity of the variant using various online software.

Conclusion

In summary, our investigation identified a novel pathogenic variant in the ANO5, responsible for gnathodiaphyseal dysplasia in a large Iranian family. Therefore, based on the present study, this variant can be helpful for diagnosis and effective management of GDD patients.

Gnathodiaphyseal dysplasia (GDD) is an ultrarare autosomal dominant bone dysplasia characterized by cementoosseous lesions of the jawbones, bone fragility, frequent bone fractures at the young age. In this study, Exome Sequencing results identified a heterozygous mutation, NM_213599.3:c.1078T>C(p.Cys360Arg) in the ANO5 confirmed by Sanger sequencing.

Sex differences in the involvement of skeletal and cardiac muscles in myopathic Ano5-/- mice

Limb-girdle muscular dystrophy R12 (LGMD-R12) is caused by recessive mutations in the Anoctamin-5 gene (ANO5, TMEM16E). Although ANO5 myopathy is not X-chromosome linked, we performed a meta-analysis of the research literature and found that three-quarters of patients with LGMD-R12 are males. Females are less likely to present with moderate to severe skeletal muscle and/or cardiac pathology. Because these sex differences could be explained in several ways, we compared males and females in a mouse model of LGMD-R12. This model recapitulates the sex differences in human LGMD-R12. Only male Ano5-/- mice had elevated serum creatine kinase after exercise and exhibited defective membrane repair after laser injury. In contrast, by these measures, female Ano5-/- mice were indistinguishable from wild type. Despite these differences, both male and female Ano5-/- mice exhibited exercise intolerance. Although exercise intolerance of male mice can be explained by skeletal muscle dysfunction, echocardiography revealed that Ano5-/- female mice had features of cardiomyopathy that may be responsible for their exercise intolerance. These findings heighten concerns that mutations of ANO5 in humans may be linked to cardiac disease.

Surgical Treatment of Pathological Tibial Shaft Fracture in Adult Patient With Gnathodiaphyseal Dysplasia: A Case Report

CASE

Gnathodiaphyseal dysplasia is a generalized skeletal syndrome characterized by frequent bone fractures in childhood, sclerosis and bowing of tubular bones, and cemento-osseous lesions of the jawbones. We present the case of a 53-year-old man with gnathodiaphyseal dysplasia who presented with pathological fracture of the tibial shaft. Internal fixation with the Ender nail was successfully performed with 2 years of follow-up.

CONCLUSION

This is the first report describing the treatment of fracture in an adult patient with gnathodiaphyseal dysplasia. Internal fixation with the Ender nail was effective for the tubular bone with deformity. Callus formation was observed without delay.

Genetic Disruption of Anoctamin 5 in Mice Replicates Human Gnathodiaphyseal Dysplasia (GDD)

Gnathodiaphyseal dysplasia (GDD; OMIM#166260) is a rare skeletal disorder which is mainly characterized by cemento-osseous lesions in mandibles, bone fragility, bowing and diaphyseal sclerosis of tubular bones. GDD is caused by point mutations in Anoctamin-5 (ANO5); however, the disease mechanisms remain unclear. Here we generated Ano5-knockout (KO) mice using a CRISPR/Cas 9 approach to study loss of function aspects of GDD mutations. Homozygous Ano5 knockout mice (Ano5^-/-) replicate some typical traits of human GDD including massive jawbones, bowing tibia, sclerosis and cortical thickening of femoral and tibial diaphyses. Serum alkaline phosphatase (ALP) levels were elevated in Ano5^-/- mice as in GDD patients. Calvaria-derived Ano5^-/- osteoblast cultures show increased osteoblastogenesis, which is consistent with our previous in vitro observations. Bone matrix is hypermineralized, and the expression of bone formation-related factors is enhanced in Ano5^-/- mice, suggesting that the osteogenic anomaly arises from a genetic disruption of Ano5. We believe this new mouse model will shed more light on the development of skeletal abnormalities in GDD on a cellular and molecular level.

Recurrent femoral shaft fractures in a child with gnathodiaphyseal dysplasia: a case report

Background

Gnathodiaphyseal dysplasia (GDD) is an extremely rare autosomal dominant disease characterized by cemento-osseous lesions in the jawbones, bone fragility, and diaphyseal sclerosis of the tubular bones. Patients with GDD are prone to sustain fractures by minor accidents. Although over 80 cases have been reported, detailed information about the orthopedic treatment of the fractures is limited.

Case presentation

A 9-year-old Japanese girl with a known history of GDD presented with pain and deformity in the left thigh after a minor fall. She had a displaced transverse fracture in the mid-shaft of the left femur and underwent a closed reduction and external fixation. In the 25th week after the initial surgery, she had another fracture in the left femur at one of the half-pin insertion sites. She underwent an external fixation again. After this operation, the patient sustained another refracture at the same fracture site and one supracondylar fracture at the distant site of the femur. The supracondylar fracture occurred without any triggering activity before beginning a weight-bearing exercise. The supracondylar fracture was successfully treated conservatively, but she sustained two more diaphyseal fractures at half-pin insertion sites one after another. She eventually underwent a revision surgery with a flexible intramedullary nail. At 3 months postoperatively, the fracture was healed and the patient maintained her ambulatory status without further refracture.

Conclusions

Patients with GDD might have narrower safety ranges of biomechanical and physiological drawbacks, which are considered to be acceptable in ordinary cases. The choice of treatment should be aimed at minimizing these negative effects. We recommend intramedullary devise as the first-choice implant for the treatment of isolated femoral shaft fracture in GDD patients in this age group.

Gnathodiaphyseal dysplasia: Severe atypical presentation with novel heterozygous mutation of the anoctamin gene (ANO5)

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.

Three novel ANO5 missense mutations in Caucasian and Chinese families and sporadic cases with gnathodiaphyseal dysplasia

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 4^th 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.

Gnathodiaphyseal Dysplasia: Surgical Treatment and Prosthetic Rehabilitation of 2 Members of the Same Family

Gnathodiaphyseal dysplasia (GDD) is a rare hereditary syndrome characterized by cemento-ossifying fibromas of the maxillary bones, fragile bones, curvature and cortical thinning of the tubular bones, and diaphyseal sclerosis of the long bones. In this study, 2 complex clinical cases of 2 members of the same family had GDD and were treated in the authors' odonto-stomatology department. The first was treated with a block bone graft and implant-prosthetic therapy; the other, who had extensive osteomyelitis of the second quadrant, was managed with extraction of the involved teeth, surgical revision of the site, and a graft of autologous platelet concentrate.

Gnathodiaphyseal dysplasia: report of a family with a novel mutation of the ANO5 gene

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.

Fibro-osseous lesions of the craniofacial skeleton: an update

Benign fibro-osseous lesions of the craniofacial skeleton (BFOL) are a variant group of intraosseous disease processes that share similar microscopic features characterized by hypercellular fibroblastic stroma containing various combinations of bone or cementum-like tissue and other calcified structures [1-6]. Whereas some are diagnosable histologically, most require a combined assessment of clinical, microscopic and radiologic features. Some BFOL of the craniofacial complex are unique to that location whereas others are encountered in bones from other regions. Reactive, neoplastic, developmental and dysplastic pathologic processes are included under the rubric of BFOL and treatment varies from disease to disease. This review will discuss the clinical, microscopic and radiologic aspects of the more important types of BFOL of the craniofacial complex with updated information on underlying genetic and molecular pathogenic mechanisms of disease. Four main groups of BFOLs will be addressed.

COL1A1 C-propeptide cleavage site mutation causes high bone mass, bone fragility and jaw lesions: a new cause of gnathodiaphyseal dysplasia?

Gnathodiaphyseal dysplasia (GDD) is a rare autosomal dominant condition characterized by bone fragility, irregular bone mineral density (BMD) and fibro-osseous lesions in the skull and jaw. Mutations in Anoctamin-5 (ANO5) have been identified in some cases. We aimed to identify the causative mutation in a family with features of GDD but no mutation in ANO5, using whole exome capture and massive parallel sequencing (WES). WES of two affected individuals (a mother and son) and the mother's unaffected parents identified a mutation in the C-propeptide cleavage site of COL1A1. Similar mutations have been reported in individuals with osteogenesis imperfecta (OI) and paradoxically increased BMD. C-propeptide cleavage site mutations in COL1A1 may not only cause 'high bone mass OI', but also the clinical features of GDD, specifically irregular sclerotic BMD and fibro-osseous lesions in the skull and jaw. GDD patients negative for ANO5 mutations should be assessed for mutations in type I collagen C-propeptide cleavage sites.

A novel missense mutation in ANO5/TMEM16E is causative for gnathodiaphyseal dyplasia in a large Italian pedigree

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.

Recurring gnathodiaphyseal dysplasia in two Russian brothers

Two Russian brothers presented with recurring benign facial bone tumors and progressive limb bowing. The association of fibro-osseous jawbone lesions and long-bone bowing with cortical thickening suggested the diagnosis of gnathodiaphyseal dysplasia, in the absence of arguments in favor of fibrous dysplasia. Gnathodiaphyseal dysplasia is a rare autonomic dominant syndrome due to a mutation of the TMEM16E gene. The extreme and recurring phenotype of these two patients illustrates the variable expressivity of this disease. Differential diagnosis with other benign facial bone tumors is discussed.