Clinical and genetic aspects in autosomal dominant inherited osteogenesis imperfecta type I

Treatments for hearing loss in osteogenesis imperfecta: a systematic review and meta-analysis on their efficacy

About 70% of people with osteogenesis imperfecta (OI) experience hearing loss. There is no cure for OI, and therapies to ameliorate hearing loss rely on conventional treatments for auditory impairments in the general population. The success rate of these treatments in the OI population with poor collagenous tissues is still unclear. Here, we conduct a systematic review and meta-analysis on the efficacy of treatments addressing hearing loss in OI. This study conforms to the reporting standards of the Preferred Reporting Items for Systematic Reviews and Meta-analyses (PRISMA). Data sources include published articles in Medline via PubMed, Web of Science, Scopus, and Embase, from their inception to November 2020. Studies included individuals with OI undergoing a hearing loss treatment, having pre- and postoperative objective assessment of hearing function at a specified follow-up length. Our search identified 1144 articles, of which 67 were reviewed at full-text screening. A random-effects meta-analysis was conducted on the selected articles (n = 12) of people with OI that underwent stapes surgery. Success was assessed as the proportion of ears with a postoperative Air-Bone Gap (ABG) ≤ 10 dB. A systematic review was conducted on the remaining articles (n = 13) reporting on other treatments. No meta-analysis was conducted on the latter due to the low number of articles on the topic and the nature of single case studies. The meta-analysis shows that stapes surgeries have a low success rate of 59.08 (95% CI 45.87 to 71.66) in the OI population. The systematic review revealed that cochlear implants, bone-anchored hearing aids, and other implantable hearing aids proved to be feasible, although challenging, in the OI population, with only 2 unsuccessful cases among the 16 reviewed single cases. This analysis of published data on OI shows poor clinical outcomes for the procedures addressing hearing loss. Further studies on hearing loss treatments for OI people are needed. Notably, the mechanisms of hearing loss in OI need to be determined to develop successful and possibly non-invasive treatment strategies.

Ocular characteristics and complications in patients with osteogenesis imperfecta: a systematic review

PURPOSE

Osteogenesis imperfecta (OI) is a rare inherited heterogeneous connective tissue disorder characterized by bone fragility, low bone mineral density, skeletal deformity and blue sclera. The dominantly inherited forms of OI are predominantly caused by mutations in either the COL1A1 or COL1A2 gene. Collagen type I is one of the major structural proteins of the eyes and therefore is the eye theoretically prone to alterations in OI. The aim of this systematic review was to provide an overview of the known ocular problems reported in OI.

METHODS

A literature search (in PubMed, Embase and Scopus), which included articles from inception to August 2020, was performed in accordance with the PRISMA guidelines.

RESULTS

The results of this current review show that almost every component of the eye could be affected in OI. Decreased thickness of the cornea and sclera is an important factor causing eye problems in patients with OI such as blue sclera. Findings that stand out are ruptures, lacerations and other eye problems that occur after minor trauma, as well as complications from standard surgical procedures.

DISCUSSION

Alterations in collagen type I affect multiple structural components of the eye. It is recommended that OI patients wear protective glasses against accidental eye trauma. Furthermore, when surgery is required, it should be approached with caution. The prevalence of eye problems in different types of OI is still unknown. Additional research is required to obtain a better understanding of the ocular defects that may occur in OI patients and the underlying pathology.

Increased cochlear otic capsule thickness and intracortical canal porosity in the oim mouse model of osteogenesis imperfecta

Osteogenesis imperfecta (OI or brittle bone disease) is a group of genetic disorders of the connective tissues caused mainly by mutations in the genes encoding collagen type I. Clinical manifestations of OI include skeletal fragility, bone deformities, and severe functional disabilities, such as hearing loss. Progressive hearing loss, usually beginning in childhood, affects approximately 70% of people with OI with more than half of the cases involving the inner ear. There is no cure for OI nor a treatment to ameliorate its corresponding hearing loss, and very little is known about the properties of OI ears. In this study, we investigate the morphology of the otic capsule and the cochlea in the inner ear of the oim mouse model of OI. High-resolution 3D images of 8-week old oim and WT inner ears were acquired using synchrotron microtomography. Volumetric morphometric measurements were conducted for the otic capsule, its intracortical canal network and osteocyte lacunae, and for the cochlear spiral ducts. Our results show that the morphology of the cochlea is preserved in the oim ears at 8 weeks of age but the otic capsule has a greater cortical thickness and altered intracortical bone porosity, with a larger number and volume density of highly branched canals in the oim otic capsule. These results portray a state of compromised bone quality in the otic capsule of the oim mice that may contribute to their hearing loss.

Stapes surgery in osteogenesis imperfecta: retrospective analysis of 18 operated ears

PURPOSE

To evaluate short and long term results of stapes surgery in patients with osteogenesis imperfecta (OI), METHODS: Retrospective case series of 18 primary stapes surgeries performed on 11 hearing-impaired OI patients with evidence of stapes fixation, in a Tertiary referral center. We analysed pre-operative and post-operative hearing results at 1 month and at least 1 year RESULTS: The main operative findings were stapes fixation, thickened footplate and fragile or fractured stapes crura. No revision surgery was necessary. Hearing improvement was achieved in 94% of the cases. We obtained an air-bone gap closure to within 10 dB in 46% of the cases and to within 15 dB in 92% of the cases at 1-year follow-up. The mean hearing gain in air conduction (at 0.5, 1, 2 and 4 kHz) was 18.4 dB at 1 month and 22.4 dB at 1 year.

CONCLUSION

Stapes surgery in OI gives good results with few complications in our series. A hearing gain is often obtained in spite of the sensorineural hearing loss caused by the natural progression of the disease.

Hearing loss in individuals with osteogenesis imperfecta in North America: Results from a multicenter study

Hearing loss (HL) is an extra-skeletal manifestation of the connective tissue disorder osteogenesis imperfecta (OI). Systematic evaluation of the prevalence and characteristics of HL in COL1A1/COL1A2-related OI will contribute to a better clinical management of individuals with OI. We collected and analyzed pure-tone audiometry data from 312 individuals with OI who were enrolled in the Linked Clinical Research Centers and the Brittle Bone Disorders Consortium. The prevalence, type, and severity of HL in COL1A1/COL1A2-related OI are reported. We show that the prevalence of HL in OI is 28% and increased with age in Type I OI but not in Types III and IV. Individuals with OI Types III and IV are at a higher risk to develop HL in the first decade of life when compared to OI Type I. We also show that the prevalence of SNHL is higher in females with OI compared to males. This study reveals new insights regarding prevalence of HL in OI including a lower general prevalence of HL in COL1A1/COL1A2-related OI than previously reported (28.3 vs. 65%) and high prevalence of SNHL in females. Our data support the need in early routine hearing evaluation in all types of OI that can be adjusted to the severity of the skeletal disease.

Swellings over the Limbs as the Earliest Feature in a Patient with Osteogenesis Imperfecta Type V

Swellings over the upper and lower limbs were encountered in a one-year-old child. Skeletal survey showed a constellation of distinctive radiographic abnormalities of osteoporosis, hyperplastic callus and ossification of the interosseous membrane of the forearm, femora, and to lesser extent the tibiae. Neither wormian bones of the skull nor dentinogenesis imperfecta was present. Genetic tests revealed absence of mutation in COL1A1 or COL1A2 genes, respectively. The overall phenotypic features were consistent with the diagnosis of osteogenesis imperfecta type V (OI-V). The aim of this paper is to distinguish between swellings because of intrinsic bone disorders and these due to child physical abuse.

Osteogenesis Imperfecta: the audiological phenotype lacks correlation with the genotype

Background

Osteogenesis Imperfecta (OI) is a heritable connective tissue disorder mainly caused by mutations in the genes COL1A1 and COL1A2 and is associated with hearing loss in approximately half of the cases. The hearing impairment usually starts between the second and fourth decade of life as a conductive hearing loss, frequently evolving to mixed hearing loss thereafter. A minority of patients develop pure sensorineural hearing loss. The interindividual variability in the audiological characteristics of the hearing loss is unexplained.

Methods

With the purpose of evaluating inter- and intrafamilial variability, hearing was thorougly examined in 184 OI patients (type I: 154; type III: 4; type IV: 26), aged 3-89 years, with a mutation in either COL1A1 or COL1A2 and originating from 89 different families. Due to the adult onset of hearing loss in OI, correlations between the presence and/or characteristics of the hearing loss and the underlying mutation were investigated in a subsample of 114 OI patients from 64 different families who were older than 40 years of age or had developed hearing loss before the age of 40.

Results

Hearing loss was diagnosed in 48.4% of the total sample of OI ears with increasing prevalence in the older age groups. The predominant type was a mixed hearing loss (27.5%). A minority presented a pure conductive (8.4%) or pure sensorineural (12.5%) loss. In the subsample of 114 OI subjects, no association was found between the nature of the mutation in COL1A1 or COL1A2 genes and the occurrence, type or severity of hearing loss. Relatives originating from the same family differed in audiological features, which may partially be attributed to their dissimilar age.

Conclusions

Our study confirms that hearing loss in OI shows a strong intrafamilial variability. Additional modifications in other genes are assumed to be responsible for the expression of hearing loss in OI.

Is it necessary to screen for hearing loss in the paediatric population with osteogenesis imperfecta?

The aim of the study was to assess the necessity of a screening service to detect early hearing loss in the paediatric population with osteogenesis imperfecta. Twenty-two children were assessed over a 5-year period. Five children (22.7%) had normal hearing. Fourteen (63.6%) had conductive hearing loss, with 12 children in this group having otitis media with effusion (OME); all had resolution of hearing loss with appropriate therapy. Two children had persistent conductive losses unrelated to OME. Three children (13.6%) had sensorineural hearing loss, with one being detected at the age of 1 year. Existing evidence suggests that hearing loss associated with osteogenesis imperfecta has its onset in the second to third decade of life. Contrary to this, hearing loss was detected in 77.3% (17) of this population with a median and mean age of 9 years. This study would suggest that routine screening is worthwhile in children with osteogenesis imperfecta.

Hearing loss in Finnish adults with osteogenesis imperfecta: a nationwide survey

Hearing loss, bone fragility, and blue sclerae are the principal clinical features in osteogenesis imperfecta (OI), a genetic disorder of connective tissue. In a nationwide search, an audiometric evaluation of 133 adult patients was performed. According to the criteria introduced by Sillence, type I was the most common form of OI. Of the patients with normal hearing on audiometry, 17.1% reported subjective hearing loss, and 19.1% of the patients with impaired hearing did not recognize it. On audiometry, 57.9% of the patients had hearing loss, which was progressive, often of mixed type, and mostly bilateral, and began in the second to fourth decades of life. The frequency or severity of the hearing loss was not correlated with any other clinical features of OI. Hearing loss is common, affecting patients with all types of OI. Subjective misjudgment of hearing ability supports the need for repeated audiometry in all OI patients. A baseline study at the age of OI years followed by audiograms every third year thereafter is recommended.

Hearing loss (in nonoperated ears) in relation to age in osteogenesis imperfecta type I

Hearing loss was studied in relation to age in nonoperated ears in a group of 142 subjects with autosomal dominant osteogenesis imperfecta type I, which was compared to that in a random subsample of 70 subjects. In the n = 142 group, particularly below the age of 30 years, considerable selection (ie, for ear surgery) had occurred on hearing loss. The hearing threshold increased gradually with age. A hearing loss of greater than 30 dB (Fletcher index) was observed for 51% of the subjects older than 20 years and younger than 60 years. The median hearing loss progressed from the 10th to the 45th years of life with an average annual threshold increase (ATI) of 1 dB/y (0.5 to 4 kHz) up to 1.7 dB/y (8 kHz). Sensorineural loss accounted for 0.6 dB/y ATI at 0.5 to 4 kHz and 1.3 dB/y ATI at 8 kHz; conductive loss accounted for 0.4 dB/y ATI at all frequencies.

Osteogenesis imperfecta and other heritable disorders of bone

This chapter summarizes the many recent advances in our understanding of the principal heritable disorders of bone. In the course of little more than a decade many diseases that were recognizable only by their clinical and radiological features have become explicable in molecular terms. Large numbers of mutations of the genes coding for collagen, for alkaline phosphatase, for the cell surface receptors for parathyroid hormone and for calcium, and for a number of other proteins, are recognized. The chapter covers the many variants of osteogenesis imperfecta, the most common heritable cause of fractures. It also covers osteopetrosis, hypophosphatasia, pseudohypoparathyroidism (with Albright's hereditary osteodystrophy), familial benign hypercalcaemia, autosomal dominant hypocalcaemia and the molecular causes of some chondrodysplasias.

Stapes surgery in osteogenesis imperfecta patients

Osteogenesis imperfecta (OI), or the Van der Hoeve-de Kleyn syndrome, is a heterogeneous group of connective tissue disorders. The key features in this disease are bone fragility with a tendency to spontaneous fractures and deformations. The classical traid of symptoms involves a conductive and/or sensorineural hearing impairment together with a tendency to spontaneous bone fractures and blue sclerae. Between January 1988 and December 1994, ear surgery was performed on eight ears of six OI patients who presented with mixed hearing loss preoperatively. Pathological changes observed in the middle ear were atrophy and/or fractures of the stapedial crura in combination with thickening and fixation of the stapes footplate. Partial stapedectomy was performed in seven cases and a neo-window was created in the promontory of one patient when an overhanging facial canal obscured visualization of the oval window niche. Pre- and postoperative bone conduction thresholds did not differ in any of the patients. Postoperatively, mean values of the air-bone gap in the main speech frequency range were below 10 dB. Functional results following stapes surgery in patients with otosclerosis during the same time interval (n = 857) did not differ significantly. These data indicate that stapes surgery in OI patients can be performed with the same functional predictability as in otosclerosis patients, even though the underlying etiology is considerably different.