Sequence of normal canine COL1A1 cDNA and identification of a heterozygous alpha1(I) collagen Gly208Ala mutation in a severe case of canine osteogenesis imperfecta

Dentinogenesis imperfecta in a 6-year-old male neutered Labrador retriever: Case report with atypical clinical presentation and treatment review

This case report details the diagnosis and treatment of dentinogenesis imperfecta in a 6-year-old neutered male Labrador, presenting without concurrent osteogenesis imperfecta. Diagnostic modalities, including radiographs, CT imaging, and histopathological examination, are reviewed in conjunction with the latest literature on canine dentinogenesis imperfecta. This patient presented at a more advanced age than typically reported cases. The clinical history, as provided by referring veterinarians, documented fractured deciduous teeth with delayed exfoliation. By 10 months of age, the patient's permanent dentition exhibited a translucent appearance and structural anomalies. Upon presentation to Eastcott Referrals the patient was experiencing significant oral pain and exhibited generalised coronal wear with yellow/brown intrinsic discolouration. CT imaging revealed that all teeth had endodontic disease and associated apical periodontitis, with varied root canal widths indicating that teeth succumbed to endodontic disease at different time points. The treatment protocol involved staged full-mouth extractions, resulting in the complete resolution of clinical symptoms. This case underscores the importance of early diagnosis and intervention in managing dentinogenesis imperfecta in dogs.

Dental Abnormalities in Two Dental-Skeletal-Retinal Anomaly-Positive Cane Corso Dogs: A Case Series

Dental-skeletal-retinal-anomaly (DSRA) is a newly described collagenopathy in Cane Corso dogs. The causative mutation has been linked with splice defects within the melanoma inhibitory activity member 3 (MIA/3) gene that codes for the TANGO1 protein. This case series presents the first dental-related radiographic and histopathological abnormalities in two dogs with genetically confirmed DSRA. The clinical, radiological, and histological features are similar to those reported for MIA3/TANGO1 splice defects previously reported in humans and knockout mice. Common clinical features of these patients include generalized opalescent discoloration of the permanent dentition (intrinsic dyschromia), enamel defects, fractured teeth, vision loss, shortened physical stature, and orthopedic abnormalities that resulted in chronic, early-onset lameness. Intraoral radiography revealed delayed dentin deposition, evidence of endodontic disease, and dental hard tissue loss in both cases. Histopathologic findings for both cases were consistent with dentinogenesis imperfecta (DGI). DSRA exhibits autosomal recessive heritability and commercial diagnostic tests are now available. Clinicians should be aware of the etiopathogenesis, genetic inheritance and associated comorbidities in order to treat and counsel clients on the management of this condition. It is recommended that all breeding individuals be tested, and carriers be sterilized or omitted from the breeding population. This case study describes intraoral diagnoses, treatments, and follow-up of two DSRA-positive dogs.

An Update on Animal Models of Osteogenesis Imperfecta

Osteogenesis imperfecta (OI) is a heterogeneous disorder characterized by bone fragility, multiple fractures, bone deformity, and short stature. In recent years, the application of next generation sequencing has triggered the discovery of many new genetic causes for OI. Until now, more than 25 genetic causes of OI and closely related disorders have been identified. However, the mechanisms of many genes on skeletal fragility in OI are not entirely clear. Animal models of OI could help to understand the cellular, signaling, and metabolic mechanisms contributing to the disease, and how targeting these pathways can provide therapeutic targets. To date, a lot of animal models, mainly mice and zebrafish, have been described with defects in 19 OI-associated genes. In this review, we summarize the known genetic causes and animal models that recapitulate OI with a main focus on engineered mouse and zebrafish models. Additionally, we briefly discuss domestic animals with naturally occurring OI phenotypes. Knowledge of the specific molecular basis of OI will advance clinical diagnosis and potentially stimulate targeted therapeutic approaches.

A Review of Dentinogenesis Imperfecta and Primary Dentin Disorders in Dogs

This review describes the clinical, radiographic and histologic characteristics of dentinogenesis imperfecta diagnosed in two unrelated young dogs without evidence of concurrent osteogenesis imperfecta. The dentition was noted to have generalized coronal discoloration ranging from grey-blue to golden brown. Clinical pulp exposure, coronal wear and fractures were observed as was radiographic evidence of endodontic disease, thin dentin walls or dystrophic obliteration of the pulp canal. The enamel was severely affected by attrition and abrasion despite histologically normal areas; loss was most likely due to poor adherence or support by the underlying abnormal dentin. Histologically, permanent and deciduous teeth examined showed thin, amorphous dentin without organized dentin tubules and odontoblasts had dysplastic cell morphology. Primary dentin disorders, including dentinogenesis imperfecta and dentin dysplasia, have been extensively studied and genetically characterized in humans but infrequently reported in dogs. Treatment in human patients is aimed at early recognition and multi-disciplinary intervention to restore and maintain normal occlusion, aesthetics, mastication and speech. Treatment in both humans and canine patients is discussed as is the documented genetic heritability of primary dentin disorders in humans.

MIA3 Splice Defect in Cane Corso Dogs with Dental-Skeletal-Retinal Anomaly (DSRA)

We investigated a hereditary syndrome in Cane Corso dogs. Affected dogs developed dental-skeletal-retinal anomaly (DSRA), clinically characterized by brittle, discolored, translucent teeth, disproportionate growth and progressive retinal degeneration resulting in vision loss. Combined linkage and homozygosity mapping delineated a 5.8 Mb critical interval. The comparison of whole genome sequence data of an affected dog to 789 control genomes revealed a private homozygous splice region variant in the critical interval. It affected the MIA3 gene encoding the MIA SH3 domain ER export factor 3, which has an essential role in the export of collagen and other secreted proteins. The identified variant, XM_005640835.3:c.3822+3_3822+4del, leads to skipping of two exons from the wild type transcript, XM_005640835.3:r.3712_3822del. Genotypes at the variant were consistent with monogenic autosomal recessive mode of inheritance in a complete family and showed perfect genotype-phenotype association in 18 affected and 22 unaffected Cane Corso dogs. MIA3 variants had previously been shown to cause related phenotypes in humans and mice. Our data in dogs together with the existing functional knowledge of MIA3 variants in other mammalian species suggest the MIA3 splice defect and a near complete loss of gene function as causative molecular pathomechanism for the DSRA phenotype in the investigated dogs.

Osteogenesis Imperfecta in Two Finnish Lapphund Puppies

Two 8-week-old Finnish Lapphund dogs presented with pain on manipulation, abnormal long bone conformation, retrognathism, and stunted growth compared to their litter mates. Multiple long bone fractures were evident on radiographs. Clinical pathology showed an atypically normal serum alkaline phosphatase activity for dogs this age. Due to poor quality of life, the dogs were humanely euthanized and subjected to a complete necropsy. On necropsy, all bones were soft and easily broken. Histologic examination revealed that the secondary spongiosa was diminished with abnormal bony trabeculae embedded in abundant loose vascular stroma. No Haversian canals were observed and the cortices contained abundant woven bone separated by fibrovascular tissue consistent with the diagnosis of osteogenesis imperfecta (OI). Inbreeding of the sire and female offspring led to a suspicion of recessive inheritance and the particular genetic collagen disorder remains to be identified in this breed.

A De Novo Mutation in COL1A1 in a Holstein Calf with Osteogenesis Imperfecta Type II

Osteogenesis imperfecta (OI) type II is a genetic connective tissue disorder characterized by bone fragility, severe skeletal deformities and shortened limbs. OI usually causes perinatal death of affected individuals. OI type II diagnosis in humans is established by the identification of heterozygous mutations in genes coding for collagens. The purpose of this study was to characterize the pathological phenotype of an OI type II-affected neonatal Holstein calf and to identify the causative genetic variant by whole-genome sequencing (WGS). The calf had acute as well as intrauterine fractures, abnormally shaped long bones and localized arthrogryposis. Genetic analysis revealed a private heterozygous missense variant in COL1A1 (c.3917T>A) located in the fibrillar collagen NC1 domain (p.Val1306Glu) that most likely occurred de novo. This confirmed the diagnosis of OI type II and represents the first report of a pathogenic variant in the fibrillar collagen NC domain of COL1A1 associated to OI type II in domestic animals. Furthermore, this study highlights the utility of WGS-based precise diagnostics for understanding congenital disorders in cattle and the need for continued surveillance for rare lethal genetic disorders in cattle.

Osteogenesis imperfecta in a male holstein calf associated with a possible oligogenic origin

Background: Neuromusculoskeletal anomalies generally in combination with severe clinical symptoms, comprise a heterogeneous group of fairly common and mostly fatal disorders in man and animals. Osteogenesis imperfecta (OI), also known as brittle bone disease, causes bone fragility and deformity. Prominent extra-skeletal accessory manifestations of OI comprise blue/gray sclerae, hearing impairment, lung abnormalities and hypercalciuria. Cases of OI in cattle have been reported. However, no causative mutations have been identified in cattle so far.Aim: To report a possible oligogenic origin identified in a calf from clinically healthy parents suffering from OI.Materials and Methods: A neonatal embryo transfer male Holstein calf developing multiple fractures with bone tissue showing marked osteopenia was used for whole genome re-sequencing as well as its parents. In addition, 2,612 randomly chosen healthy Holstein cattle were genotyped as well as controls.Results: Sixteen candidate genes with potential protein-altering variants were selected revealing non-synonymous variants only within IFITM5 and CRTAP genes. However, in-depth gene analysis did not result in the identification of a single causative mutation in the OI calf.Conclusion: The analysis of the OI case revealed a possible oligogenic origin of the disease attributable to additive effects of three candidate genes, i.e., ABCA13, QRFPR, and IFTIM5.Clinical relevance: Most OI cases in humans and domestic animals reported so far are caused by distinct dominant or recessive monogenic mutations, therefore a potential oligogenic additive genetic effect is a novel finding. Furthermore, the case presented here demonstrates that cross-species genetic analyses might not always be straightforward.

Whole Genome Sequencing Indicates Heterogeneity of Hyperostotic Disorders in Dogs

Craniomandibular osteopathy (CMO) and calvarial hyperostotic syndrome (CHS) are proliferative, non-neoplastic disorders affecting the skull bones in young dogs. Different forms of these hyperostotic disorders have been described in many dog breeds. However, an incompletely dominant causative variant for CMO affecting splicing of SLC37A2 has been reported so far only in three Terrier breeds. The purpose of this study was to identify further possible causative genetic variants associated with CHS in an American Staffordshire Terrier, as well as CMO in seven affected dogs of different breeds. We investigated their whole-genome sequences (WGS) and filtered variants using 584 unrelated genomes, which revealed no variants shared across all affected dogs. However, filtering for private variants of each case separately yielded plausible dominantly inherited candidate variants in three of the eight cases. In an Australian Terrier, a heterozygous missense variant in the COL1A1 gene (c.1786G>A; p.(Val596Ile)) was discovered. A pathogenic missense variant in COL1A1 was previously reported in humans with infantile cortical hyperostosis, or Caffey disease, resembling canine CMO. Furthermore, in a Basset Hound, a heterozygous most likely pathogenic splice site variant was found in SLC37A2 (c.1446+1G>A), predicted to lead to exon skipping as shown before in SLC37A2-associated canine CMO of Terriers. Lastly, in a Weimaraner, a heterozygous frameshift variant in SLC35D1 (c.1021_1024delTCAG; p.(Ser341ArgfsTer22)) might cause CMO due to the critical role of SLC35D1 in chondrogenesis and skeletal development. Our study indicates allelic and locus heterogeneity for canine CMO and illustrates the current possibilities and limitations of WGS-based precision medicine in dogs.

Identification of a Candidate Mutation in the COL1A2 Gene of a Chow Chow With Osteogenesis Imperfecta

Osteogenesis imperfecta (OI) is a genetic disease that occurs in humans and animals. Individuals with OI exhibit signs of extreme bone fragility and osteopenia with frequent fractures and perinatal lethality in severe cases. In this study, we report the clinical diagnosis of OI in a dog and the use of targeted next-generation sequencing to identify a candidate autosomal dominant mutation in the COL1A2 gene. A 5-month-old male Chow Chow was examined with a fractured left humerus and resolving, bilateral femoral fractures. Radiographs revealed generalized osteopenia and bilateral humeral, radial, and femoral fractures. Targeted next-generation sequencing of genes associated with OI in humans (COL1A1, COL1A2, LEPRE1, SERPINH1, and CRTAP) revealed a G>A heterozygous mutation in the splice donor site of exon 18 of the COL1A2 gene (c.936 + 1G>A). The splice donor mutation was not detected among 91 control dogs representing 21 breeds. A comparative analysis of exon 18 and the exon-intron junction further showed that the mutated splice donor site is conserved among vertebrates. Altogether, these findings reveal a candidate autosomal splice donor site mutation causing OI in an individual Chow Chow.

A homozygous missense variant in the alkaline phosphatase gene ALPL is associated with a severe form of canine hypophosphatasia

Inherited skeletal disorders affect both humans and animals. In the current study, we have performed series of clinical, pathological and genetic examinations to characterize a previously unreported skeletal disease in the Karelian Bear Dog (KBD) breed. The disease was recognized in seven KBD puppies with a variable presentation of skeletal hypomineralization, growth retardation, seizures and movement difficulties. Exome sequencing of one affected dog revealed a homozygous missense variant (c.1301T > G; p.V434G) in the tissue non-specific alkaline phosphatase gene, ALPL. The identified recessive variant showed full segregation with the disease in a cohort of 509 KBDs with a carrier frequency of 0.17 and was absent from 303 dogs from control breeds. In humans, recessive and dominant ALPL mutations cause hypophosphatasia (HPP), a metabolic bone disease with highly heterogeneous clinical manifestations, ranging from lethal perinatal hypomineralization to a relatively mild dental disease. Our study reports the first naturally occurring HPP in animals, resembling the human infantile form. The canine HPP model may serve as a preclinical model while a genetic test will assist in breeding programs.

Digging for known genetic mutations underlying inherited bone and cartilage characteristics and disorders in the dog and cat

Gene mapping projects for many traits in both dogs and cats have yielded new knowledge. Both researchers and the public alike have been fascinated by the inheritance of breed characteristic phenotypes and sporadic disorders. It has been proposed that selective breeding practices have on occasion generated alterations in structure that might be harmful. In this review, simply inherited disorders and characteristics affecting bone and cartilage for which a putative mutation is known are collected. A better understanding of the known inherited basis of skeletal conditions and disorders will assist veterinarians to improve their diagnoses and increase their effectiveness on advising clients on the prevention, management, prognosis and possible treatment of the conditions.

Animal models of osteogenesis imperfecta: applications in clinical research

Osteogenesis imperfecta (OI), commonly known as brittle bone disease, is a genetic disease characterized by extreme bone fragility and consequent skeletal deformities. This connective tissue disorder is caused by mutations in the quality and quantity of the collagen that in turn affect the overall mechanical integrity of the bone, increasing its vulnerability to fracture. Animal models of the disease have played a critical role in the understanding of the pathology and causes of OI and in the investigation of a broad range of clinical therapies for the disease. Currently, at least 20 animal models have been officially recognized to represent the phenotype and biochemistry of the 17 different types of OI in humans. These include mice, dogs, and fish. Here, we describe each of the animal models and the type of OI they represent, and present their application in clinical research for treatments of OI, such as drug therapies (ie, bisphosphonates and sclerostin) and mechanical (ie, vibrational) loading. In the future, different dosages and lengths of treatment need to be further investigated on different animal models of OI using potentially promising treatments, such as cellular and chaperone therapies. A combination of therapies may also offer a viable treatment regime to improve bone quality and reduce fragility in animals before being introduced into clinical trials for OI patients.

Population screening for the mutation associated with osteogenesis imperfecta in dachshunds

Osteogenesis imperfecta (OI) is a genetic disorder causing defects in the development of collagen type I. Clinical signs of affected dachshunds include multiple fractures of bones, joint hyperlaxity and dentinogenesis imperfecta. Recently, a recessive mutation in the SERPINH1 gene was detected in dachshunds and enabled the development of a DNA test to identify dachshunds carrying the mutation. The purpose of the present study was to analyse the dachshund breeding population for the frequency of the SERPINH1 mutation among the nine different breed varieties in dachshunds, birth years and countries of origin. We genotyped the OI-associated SERPINH1 mutation in 1352 dachshunds from 12 different European countries including all nine varieties. Genotyping was done using a restriction fragment length polymorphism validated by DNA sequence analysis. The overall frequency of OI carriers was 12.9 per cent. Across all different size varieties, the SERPINH1 mutation was over-represented in wire-haired dachshunds with 17.3 per cent OI carriers. Among the different countries, the proportion of OI carriers was highest in Germany with 20.4 per cent. The test is useful for dachshund breeders to prevent the occurrence of OI-affected dogs and as a diagnostic tool for veterinarians.

A novel GUSB mutation in Brazilian terriers with severe skeletal abnormalities defines the disease as mucopolysaccharidosis VII

Hundreds of different human skeletal disorders have been characterized at molecular level and a growing number of resembling dysplasias with orthologous genetic defects are being reported in dogs. This study describes a novel genetic defect in the Brazilian Terrier breed causing a congenital skeletal dysplasia. Affected puppies presented severe skeletal deformities observable within the first month of life. Clinical characterization using radiographic and histological methods identified delayed ossification and spondyloepiphyseal dysplasia. Pedigree analysis suggested an autosomal recessive disorder, and we performed a genome-wide association study to map the disease locus using Illumina’s 22K SNP chip arrays in seven cases and eleven controls. A single association was observed near the centromeric end of chromosome 6 with a genome-wide significance after permutation (p_genome  = 0.033). The affected dogs shared a 13-Mb homozygous region including over 200 genes. A targeted next-generation sequencing of the entire locus revealed a fully segregating missense mutation (c.866C>T) causing a pathogenic p.P289L change in a conserved functional domain of β-glucuronidase (GUSB). The mutation was confirmed in a population of 202 Brazilian terriers (p = 7,71×10⁻²⁹). GUSB defects cause mucopolysaccharidosis VII (MPS VII) in several species and define the skeletal syndrome in Brazilian Terriers. Our results provide new information about the correlation of the GUSB genotype to phenotype and establish a novel canine model for MPS VII. Currently, MPS VII lacks an efficient treatment and this model could be utilized for the development and validation of therapeutic methods for better treatment of MPS VII patients. Finally, since almost one third of the Brazilian terrier population carries the mutation, breeders will benefit from a genetic test to eradicate the detrimental disease from the breed.

A missense mutation in the SERPINH1 gene in Dachshunds with osteogenesis imperfecta

Osteogenesis imperfecta (OI) is a hereditary disease occurring in humans and dogs. It is characterized by extremely fragile bones and teeth. Most human and some canine OI cases are caused by mutations in the COL1A1 and COL1A2 genes encoding the subunits of collagen I. Recently, mutations in the CRTAP and LEPRE1 genes were found to cause some rare forms of human OI. Many OI cases exist where the causative mutation has not yet been found. We investigated Dachshunds with an autosomal recessive form of OI. Genotyping only five affected dogs on the 50 k canine SNP chip allowed us to localize the causative mutation to a 5.82 Mb interval on chromosome 21 by homozygosity mapping. Haplotype analysis of five additional carriers narrowed the interval further down to 4.74 Mb. The SERPINH1 gene is located within this interval and encodes an essential chaperone involved in the correct folding of the collagen triple helix. Therefore, we considered SERPINH1 a positional and functional candidate gene and performed mutation analysis in affected and control Dachshunds. A missense mutation (c.977C>T, p.L326P) located in an evolutionary conserved domain was perfectly associated with the OI phenotype. We thus have identified a candidate causative mutation for OI in Dachshunds and identified a fifth OI gene.

Temporal gene expression following prosthetic arterial grafting

BACKGROUND

Following prosthetic arterial grafting, cytokines and growth factors released within the perianastomotic tissues stimulate smooth muscle cell proliferation and matrix production. While much in vitro work has characterized this response, little understanding exists regarding the sequential up- and down-regulation of genes following prosthetic arterial grafting. This study evaluates temporal gene expression at the distal anastomosis of prosthetic arterial grafts using microarray analysis.

METHODS

Expanded polytetrafluoroethylene (ePTFE) carotid interposition grafts (n = 12) were surgically implanted into mongrel dogs. Distal anastomotic segments were harvested at 7, 14, 30, or 60 days. Contralateral carotid artery served as control. Total RNA was isolated from the anastomotic tissue and paired controls. Samples were probed with oligonucleotide microarrays consisting of approximately 10000 human genes to analyze differential gene expression at each time point.

RESULTS

Forty-nine genes were found to be up-regulated and 37 genes were found to be down-regulated at various time points. Six genes were found to be consistently up-regulated at all time intervals, including collagen type 1 alpha-1 and alpha-2, 80K-L protein (MARCKS), and osteopontin. Six genes were found to be consistently down-regulated, including smoothelin and tropomyosin 2. RT-PCR and immunohistochemistry confirmed the microarray data.

CONCLUSIONS

This study uses microarray analysis to identify genes that were temporally up- and down-regulated after prosthetic arterial grafting. Genes with similar patterns of expression have been identified, providing insights into related cellular pathways that may result in the formation of anastomotic intimal hyperplasia.

Osteogenesis imperfecta in two litters of dachshunds

A clinical, morphologic, ultrastructural, and genetic study was performed on five rough-coated dachshund semisiblings with osteogenesis imperfecta (OI). Clinical signs consisted of pain, spontaneous bone and teeth fractures, joint hyperlaxity, and reduced bone density on radiography. Primary teeth were extremely thin-walled and brittle. The hallmark of the disease was a severe osteopenia characterized by impairment of lamellar bone formation in the long bones, skull, and vertebral column. No deformity or dwarfism was present. The columns of chondrocytes and primary trabeculae in the epiphyses and metaphyses were histologically normal. An abrupt failure of secondary spongiosa and lamellar bone formation was evident in the medullary and cortical zones in all animals. The few existing trabeculae consisted of woven bone. There was no increase in the number and size of osteoclasts or lacunae. In the teeth, the dentine layers were thin and lacked a tubular pattern. Ultrastructurally, osteoid apposition on bone surfaces was reduced, and small numbers of large cytoplasmic vacuoles were present in a few osteoblasts. Molecular analyses of the collagen type I-encoding genes COL1A1 and COL1A2 revealed several nucleotide differences compared with the published canine sequences but were not significant for OI. Therefore, OI in these Dachshund litters was characterized by a severe, generalized osteopenia and dentinopenia. This pattern of reduced bone formation is suggestive of defective production of collagen type I.

RNase cleavage-based methods for mutation/SNP detection, past and present

Mutation detection based on ribonuclease cleavage of basepair mismatches in single-stranded RNA probes hybridized to DNA targets was first described over 15 years ago. The original methods relied on RNase A for mismatch cleavage; however, this enzyme fails to cleave many mismatches and has other drawbacks. More recently, a new method for RNase-cleavage-based mutation scanning has been developed, which takes advantage of the ability of RNase 1 and RNase T1 to cleave mismatches in duplex RNA targets, when these enzymes are used in conjunction with nucleic acid intercalating dyes. The method, called NIRCA, is relatively low-cost in terms of materials and equipment required. It is being used to detect mutations and SNPs in a wide variety of genes involved in human genetic disease and cancer, as well as in disease-related viral and bacterial genes. This review describes historical and recently developed RNase cleavage-based methods for mutation/SNP scanning.

Canine COL1A2 mutation resulting in C-terminal truncation of pro-alpha2(I) and severe osteogenesis imperfecta

RNA and type I collagen were analyzed from cultured skin fibroblasts of a Beagle puppy with fractures consistent with type III osteogenesis imperfecta (OI). In a nonisotopic RNAse cleavage assay (NIRCA), the proband's RNA had a unique cleavage pattern in the region of COL1A2 encoding the C-propeptide. DNA sequence analyses identified a mutation in which nucleotides 3991-3994 ("CTAG") were replaced with "TGTCATTGG." The first seven bases of the inserted sequence were identical to nucleotides 4002-4008 of the normal canine COL1A2 sequence. The resulting frameshift changed 30 amino acids and introduced a premature stop codon. Reverse-transcription polymerase chain reaction (RT-PCR) with primers flanking the mutation site amplified two complementary DNA (cDNA) fragments for the proband and a single product for the control. Restriction enzyme digestions also were consistent with a heterozygous mutation in the proband. Type I procollagen labeled with [3H]proline was analyzed by sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE). Increased density of pC-alpha2(I) suggested comigration with the similarly sized pro-alpha2(I) derived from the mutant allele. Furthermore, a-chains were overhydroxylated and the ratio of alpha1(I):alpha2(I) was 3.2:1, consistent with the presence of alpha1(I) homotrimers. Analyses of COL1A2 and type I collagen were both consistent with the described heterozygous mutation affecting the pro-alpha2(I) C-propeptide and confirmed a diagnosis of OI.