Case Report: A Novel COL1A1 Missense Mutation Associated With Dentineogenesis Imperfecta Type I

Background: Osteogenesis imperfecta (OI) is a clinical and genetic disorder that results in bone fragility, blue sclerae and dentineogenesis imperfecta (DGI), which is mainly caused by a mutation in the COL1A1 or COL1A2 genes, which encode type I procollagen.Case Report: A missense mutation (c.1463G > C) in exon 22 of the COL1A1 gene was found using whole-exome sequencing. However, the cases reported herein only exhibited a clinical DGI-I phenotype. There were no cases of bone disease or any other common abnormal symptom caused by a COL1A1 mutation. In addition, the ultrastructural analysis of the tooth affected with non-syndromic DGI-I showed that the abnormal dentine was accompanied by the disruption of odontoblast polarization, a reduced number of odontoblasts, a reduction in hardness and elasticity, and the loss of dentinal tubules, suggesting a severe developmental disorder. We also investigated the odontoblast differentiation ability using dental pulp stem cells (DPSCs) that were isolated from a patient with DGI-I and cultured. Stem cells isolated from patients with DGI-I are important to elucidate their pathogenesis and underlying mechanisms to develop regenerative therapies.Conclusion: This study can provide new insights into the phenotype-genotype association in collagen-associated diseases and improve the clinical diagnosis of OI/DGI-I.

Whole Exome Sequencing Identifies a Novel COL1A1 Missense Mutation Causing Dentinogenesis Imperfecta Type I Without Skeletal Abnormalities

Background：Osteogenesis imperfecta (OI) is a genetic disorder characterized by bone fragility, blue sclerae and dentinogenesis imperfecta (DGI), which are mainly caused by a mutation of the COL1A1 or COL1A2 genes that encode type I procollagen.Methods: The ultrastructure of dentin was analyzed by micro-CT, scanning electron microscopy, energy-dispersive spectroscopy analysis, nanoindentation test and Toluidine Blue Staining. Whole-exome sequencing (WES) was performed to identify the pathogenic gene. The function of the mutant COL1A1 was studied by real-time PCR, western blotting, subcellular localization. Functional analysis in dental pulp stem cells (DPSCs) was also performed to explore the impact of the identified mutation on this phenotype. Results: WES identified a missense mutation (c.1463G > C) in exon 22 of the COL1A1 gene. However, the cases reported herein only exhibited DGI-I in the clinical phenotype, there is no bone disease and any other common abnormal symptom caused by COL1A1 mutation. In addition, ultrastructural analysis of the tooth affected with non-syndromic DGI-I showed that the abnormal dentin was accompanied by disruption of odontoblast polarization, reduced numbers of odontoblasts, loss of dentinal tubules, and reduction in hardness and elasticity, suggesting severe developmental disturbance. What’s more, the odontoblast differentiation ability based on DPSCs that were isolated and cultured from the DGI-I patient was enhanced compared with those from an age-matched, healthy control.Conclusion: This study helped the family members to understand the disease progression and provided new insights into the phenotype-genotype association in collagen-associated diseases and improve clinical diagnosis of OI/DGI-I.

The first case report of Kyphoscoliotic Ehlers-Danlos syndrome of chinese origin with a novel PLOD1 gene mutation

Background Kyphoscoliotic Ehlers-Danlos syndrome (kEDS) is a rare autosomal recessive connective tissue disorder characterized by progressive kyphoscoliosis, congenital muscular hypotonia, marked joint hypermobility, and severe skin hyperextensibility and fragility. Deficiency of lysyl hydroxylase 1 (LH1) due to mutations of PLOD1 (procollagen-lysine, 2-oxoglutarate 5-dioxygenase 1) gene has been identified as the pathogenic cause of kEDS (kEDS-PLOD1). Up to now, kEDS-PLOD1 has not been reported among Chinese population. Case presentation A 17-year-old Chinese male patient presenting with hypotonia, joint hypermobility and scoliosis was referred to our hospital. After birth, he was found to have severe hypotonia leading to delayed motor development. Subsequently, joint hypermobility, kyphoscoliosis and amblyopia were found. Inguinal hernia was found at age 5 years and closed by surgery. At the same time, he presented with hyperextensible and bruisable velvety skin with widened atrophic scarring after minor trauma. Dislocation of elbow joint was noted at age of 6 years. Orthopedic surgery for correction of kyphoscoliosis was performed at age 10 years. His family history was unremarkable. Physical examination revealed elevated blood pressure. Slight facial dysmorphologies including high palate, epicanthal folds, and down-slanting palpebral fissures were found. He also had blue sclerae with normal hearing. X-rays revealed severe degree of scoliosis and osteopenia. The Echocardiography findings were normal. Laboratory examination revealed a slightly elevated bone turnover. Based on the clinical manifestations presented by our patient, kEDS was suspected. Genetic analysis revealed a novel homozygous missense mutation of PLOD1 (c.1697 G > A, p.C566Y), confirming the diagnosis of kEDS-PLOD1. The patient was treated with alfacalcidol and nifedipine. Improved physical strength and normal blood pressure were reported after 12-month follow-up. Conclusions This is the first case of kEDS-PLOD1 of Chinese origin. We identified one novel mutation of PLOD1, extending the mutation spectrum of PLOD1. Diagnosis of kEDS-PLOD1 should be considered in patients with congenital hypotonia, progressive kyphoscoliosis, joint hypermobility, and skin hyperextensibility and confirmed by mutation analysis of PLOD1.

Fatigue in adults with Osteogenesis Imperfecta

Background Osteogenesis Imperfecta (OI) is characterized by bone fragility, and features such as blue sclerae, dentinogenesis imperfecta, hearing loss, ligamentous laxity and short stature can be present. It has long been assumed that the functional ability and quality of life of patients with OI depends primarily on the severity of skeletal deformities. However, fatigue is often mentioned in clinic by patients with all types of OI as an important modifier of their quality of life and does not always seem to be related to their functional ability. The aim of this study is to investigate whether adults with Osteogenesis Imperfecta are significantly more fatigued than the normal population. Methods The Fatigue Severity Scale (FSS) was distributed by mobile phone application among 151 adult patients with different OI types. Results of the FSS in the OI group were compared with two control populations from America (n = 20) and the Netherlands (n = 113). Results Ninety-nine patients (OI type 1 (n = 72), OI type 3 (n = 13), OI type 4 (n = 14) completed the FSS questionnaire. The mean FSS score of this cohort was 4.4 and significantly higher than the control populations (2.3/2.9). 65% of our cohort reported at least moderate fatigue compared with 2 control populations from America and the Netherlands. Conclusion Fatigue in patients with OI is a frequently encountered problem in our expert clinic but research into this topic is sparse. This pilot study is the largest study to date investigating fatigue in patients with OI and results have been compared with two control groups. The mean FSS score of 4.4 in the OI group indicates that people with OI are generally significantly more fatigued than the control population. Further evaluation of fatigue and its influencers in a larger group of OI patients is important for future management.

Osteogenesis Imperfecta

Osteogenesis imperfecta (OI) is a genetic disorder that affects collagen formation and ultimately leads to increased bone fragility. The fragile nature of the bones leads to fractures, even from seemingly normal patient care. Affected patients are at the highest risk for unintentional fractures during perioperative care. There are several different types of OI. Type I is the most common. With the different types come varying degrees of severity. Types II and III are the more severe forms. The classic clinical triad seen in OI is blue sclerae, multiple fractures, and conductive hearing loss. The patient may have other systemic involvement beyond the fragile musculoskeletal system. It is imperative that the anesthesiologist be well-versed in the natural history and perioperative management of patients with OI in order to optimize care and minimize complications.

FAM46A mutations are responsible for autosomal recessive osteogenesis imperfecta

BackgroundStüve-Wiedemann syndrome (SWS) is characterised by bowing of the lower limbs, respiratory distress and hyperthermia that are often responsible for early death. Survivors develop progressive scoliosis and spontaneous fractures. We previously identified LIFR mutations in most SWS cases, but absence of LIFR pathogenic changes in five patients led us to perform exome sequencing and to identify homozygosity for a FAM46A mutation in one case [p.Ser205Tyrfs*13]. The follow-up of this case supported a final diagnosis of osteogenesis imperfecta (OI), based on vertebral collapses and blue sclerae.Methods and resultsThis prompted us to screen FAM46A in 25 OI patients with no known mutations.We identified a homozygous deleterious variant in FAM46A in two affected sibs with typical OI [p.His127Arg]. Another homozygous variant, [p.Asp231Gly], also classed as deleterious, was detected in a patient with type III OI of consanguineous parents using homozygosity mapping and exome sequencing.FAM46A is a member of the superfamily of nucleotidyltransferase fold proteins but its exact function is presently unknown. Nevertheless, there are lines of evidence pointing to a relevant role of FAM46A in bone development. By RT-PCR analysis, we detected specific expression of FAM46A in human osteoblasts andinterestingly, a nonsense mutation in Fam46a has been recently identified in an ENU-derived (N-ethyl-N-nitrosourea) mouse model characterised by decreased body length, limb, rib, pelvis, and skull deformities and reduced cortical thickness in long bones.ConclusionWe conclude that FAM46A mutations are responsible for a severe form of OI with congenital bowing of the lower limbs and suggest screening this gene in unexplained OI forms.

Management of Multiple Mandibular Fractures in a Child with Osteogenesis Imperfecta Using Arch Bar Retained Thermoformed Splints: A Novel Technique

Osteogenesis Imperfecta (OI) is a heterogeneous group of autosomal dominant and recessive inherited disorders of type I collagen metabolism. Clinical features of OI include multiple bone fractures, muscle weakness, joint laxity, skeletal deformities, blue sclerae, hearing loss, and dentinogenesis imperfecta. This report presents a challenging case of multiple mandibular fractures in a five years old child with OI, which was successfully treated with a new, minimally invasive technique of closed reduction with arch bar retained thermoformed splint.