Stickler Syndrome Research Articles

Clinical phenocopies of albinism

To present a series of patients diagnosed with oculocutaneous albinism (OCA) based on clinical presentation who were later proven to have a different diagnosis. The medical records of patients seen at the Pediatric Inherited Eye Disease Clinic of the University of Iowa from 1980 to 2018 who were eventually discovered to have an incorrect diagnosis of OCA were reviewed retrospectively. Eight pediatric patients presenting with clinical features suggestive of OCA which changed to a different diagnosis over time were identified. Presenting clinical features included fair pigmentation of the skin and adnexa (8/8), congenital nystagmus (6/8), decreased visual acuity (8/8), iris transillumination defects (8/8), and foveal hypoplasia (7/8). Of the 8 patients, 4 manifested progressive, preschool-age-onset myopia. Other associated clinical features included hearing loss (3), seizures (1), abnormal chest x-ray (1) and easy bruising (2). During follow-up, additional clinical features and genetic testing proved that they have different clinical entities, namely, Knobloch syndrome, Jeune syndrome, Donnai-Barrow syndrome, Waardenburg syndrome, Aniridia syndrome, Stickler syndrome, and Hermansky-Pudlak syndrome, one of the syndromic types of OCA. Clinical features used to diagnose OCA also occur in other disorders. For a definitive diagnosis of OCA, ancillary/genetic testing must be performed. Clinical features not typically found in association with albinism, such as hearing loss, or early onset, or progressive myopia, may indicate the need for more extensive investigation.

Hearing Outcomes in Stickler Syndrome: Variation Due to COL2A1 and COL11A1.

Stickler syndrome (SS) is a heterogeneous inherited connective tissue disorder, often due to a mutation in COL2A1 or COL11A1. Mutations in these genes cause collagen abnormalities affecting ocular, auditory, orofacial, and skeletal systems, including hearing loss, micrognathia, and cleft palate. Understanding the variability of hearing phenotypes based on genetic mutation has a significant impact on treatment and long-term care. A retrospective chart review of pediatric patients with a confirmed diagnosis of SS between January 2003 and December 2018 at a tertiary pediatric hospital was performed. Patients were excluded if they did not have genetic evaluation, craniofacial/ear, nose, and throat evaluation, and/or audiologic testing. Charts were reviewed for the following information: age, race, sex, SS diagnosis, genetic variant of SS, and audiological testing data. There were 29 confirmed patients with SS who met criteria, 16 with type I (COL2A1) and 13 with type II (COL11A1). Of the 13 patients with type II, 12 (92%) demonstrated hearing loss, ranging in severity from mild to severe. In type I, 25% of patients had mild or resolved hearing loss. Results suggest that patients with type II SS are more likely to have congenital hearing loss than type I. Data also suggest that the COL11A1 mutation shows consistently more severe hearing loss than the COL2A1 mutation.

Targeted Deletion of Loxl3 by Col2a1-Cre Leads to Progressive Hearing Loss

Collagens are major constituents of the extracellular matrix (ECM) that play an essential role in the structure of the inner ear and provide elasticity and rigidity when the signals of sound are received and transformed into electrical signals. LOXL3 is a member of the lysyl oxidase (LOX) family that are copper-dependent amine oxidases, generating covalent cross-links to stabilize polymeric elastin and collagen fibers in the ECM. Biallelic missense variant of LOXL3 was found in Stickler syndrome with mild conductive hearing loss. However, available information regarding the specific roles of LOXL3 in auditory function is limited. In this study, we showed that the Col2a1-Cre-mediated ablation of Loxl3 in the inner ear can cause progressive hearing loss, degeneration of hair cells and secondary degeneration of spiral ganglion neurons. The abnormal distribution of type II collagen in the spiral ligament and increased inflammatory responses were also found in Col2a1–Loxl3–/– mice. Amino oxidase activity exerts an effect on collagen; thus, Loxl3 deficiency was expected to result in the instability of collagen in the spiral ligament and the basilar membrane, which may interfere with the mechanical properties of the organ of Corti and induce the inflammatory responses that are responsible for the hearing loss. Overall, our findings suggest that Loxl3 may play an essential role in maintaining hearing function.

Whole exome sequencing identified a pathogenic mutation of COL2A1 causing Stickler syndrome in a Vietnamese family

Stickler syndrome is a group of rare inherited diseases associated with abnormalities in connective tissues, specifically collagen of the eyes, ears, craniofacies, skeleton and joints. The inheritance pattern of this disease is either an autosomal dominant or an autosomal recessive based on the causative gene. Stickler syndrome is characterized by severe nearsightedness, vitreous abnormalities, distinctive facial features, hearing problems and joint anomalies. Herein, we report a case of a 37-year-old man from Vietnam suspected of Stickler syndrome, presenting a phenotype of retinal detachment and complete loss of vision, and his 3-year-old son with congenital high myopia and vitreous abnormalities. Genetic analysis using whole exome sequencing (WES) revealed a nucleotide substitution (c.C2818T/p.R940X) in exon 42 of the COL2A1 gene that was previously reported as a pathogenic variant causing Stickler syndrome. Validation of COL2A1 c.C2818T in all members of this family by using Sanger sequencing detected the presence of this pathogenic variant in the heterozygous form in the affected father and son but not in the mother and another son without any signs of a vision problem. Thus, our study contributes to not only the knowledge base of clinical and genetic aspects of Stickler syndrome in Vietnam but also the awareness of the importance of genetic counseling in patients with COL2A1 c.C2818T mutation, as well as early diagnosis and appropriate treatment to prevent serious complications, especially blindness.

Genetic testing results of children suspected to have Stickler syndrome type collagenopathy after ocular examination.

PurposeStickler syndrome is a collagenopathy that is typically COL2A1‐related (autosomal dominant) and less commonly related to other collagen gene mutations. Diagnosis is straightforward when a child has myopia or retinal detachment in the setting of classic diagnostic criteria such as hearing impairment, midfacial hypoplasia, and arthropathy. However, some children have primarily ocular disease with mild or no extraocular features. Such children can remain undiagnosed unless suspicion is raised by the ophthalmologist.MethodsRetrospective consecutive case series (2014–2016) of children (<12 years old) suspected to have Stickler syndrome type collagenopathy by a single ophthalmologist and able to complete genetic testing for this possibility. Suspicion was based on vitreous abnormalities and myopia or lens opacities in the setting of prior retinal detachment, hearing impairment, or facial flatness.ResultsAverage age of the 12 identified children was 8 years old (range 3–11; five boys). Average spherical equivalent for phakic eyes was −13 (range −3.5 to −30). Nine children had lens opacities or aphakia; two with aphakia also had lens subluxation or iridodonesis. Other recurrent clinical features included flat facies (12/12), hearing impairment (5/12), and prior retinal detachment (4/12). Pathogenic variants for collagenopathy were uncovered in 10/12 children: COL11A1 (heterozygous) in six, COL2A1 (heterozygous) in two, and COL9A1 (homozygous) in two. One child was homozygous for pathogenic variation in LRPAP1. One child had no detectable gene mutations.ConclusionsTaken together, these clinical features (particularly vitreous abnormality, myopia, and lens opacity) had a high molecular yield for collagen gene mutation. Ophthalmologists who see such children should suspect Stickler syndrome, even in the absence of overt systemic disease. COL11A1‐related rather than COL2A1‐related autosomal dominant disease may be more common when undiagnosed children are identified based on ocular examination. Biallelic mutations in LRPAP1 can result in a phenotype that may resemble Stickler syndrome.

Incidence of mandibular distraction osteogenesis in Stickler Syndrome: Variation due to COL2A1 and COL11A1

ObjectiveTo determine whether the two most common genetic mutations seen in Stickler Syndrome (SS) (COL2A1 and COL11A1) affect the incidence of mandibular distraction osteogenesis (MDO) and what impact Robin sequence (RS) has on diagnosis. SS is an autosomal dominant connective tissue disorder characterized by almost complete penetrance. COL2A1 and COL11A1 are the two most common mutations seen in SS patients. SS often presents at birth with RS, which is characterized by the triad of micrognathia, glossoptosis, and tongue-based airway obstruction. MDO is one surgical intervention that has been shown to be successful in relieving tongue base obstruction and is the surgical intervention of choice for this condition. MethodsA retrospective chart review was performed on all patients with a diagnosis of SS at a tertiary pediatric hospital between January 1, 2003 and December 31, 2018. The included patient charts were reviewed for demographic information, SS mutation, and history of MDO. Forty-six patients had a clinical diagnosis of SS. Of those, 31 met inclusion criteria which involved having a molecular diagnosis of SS and sufficient follow up information to determine if MDO was indicated or performed. Twenty-two of the 31 included patients had a diagnosis of RS (70.96%). Thirteen of the 31 patients (41.94%) included in this study required MDO as a neonate. ResultsFifty-percent of patients with type I (COL2A1) required MDO as a neonate compared to only 31% of patients with type II (COL11A1), though the difference between the two groups was not statistically significant. ConclusionThe findings of this study suggest that patients with type I mutation may have a higher incidence of MDO than patients with a type II mutation, though further research with larger sample sizes is needed. This information is helpful in counseling those with SS or family history of SS about what they can expect related to RS and need for MDO based on genetic findings. Level of Evidence3

Sticklerův syndrom v České republice: fenotypová variabilita a genetická heterogenita

Stickler syndrome (STL) is a progressive multisystemic disorder of connective tissue with an incidence of 1:7,500 newborns, which is probably underestimated due to its considerable clinical and genetic heterogeneity. STL symptoms include cleft palate or the Pierre-Robin sequence, hearing and/ or vision impairment, namely early high myopia and spontaneous retinal detachment, skeletal dysplasia, and a characteristic facial appearance, including a flat profile, protruding eyes, and micrognathia. STL symptoms show high inter- and even intrafamilial phenotypical variability. Variants in seven different collagen genes can cause STL. Autosomal dominant (AD) type 1 caused by a defect in the COL2A1 gene is the most common form of STL (80–90%); AD type 2 (involving COL11A1 gene defects) is much less common (10–20%). The third AD type and all autosomal recessive types are extremely rare. A genetically confirmed dia­gnosis of STL facilitates early treatment, prevention, and an accurate genetic risk estimation of STL in the family.

Surgical treatment of vitreoretinal complications in a patient with Stickler syndrome type 1: a case report

We present the clinical case of an 8-years-old male patient with a genetic diagnosis of Stickler syndrome type 1 and the management of associated vitreoretinal complications. The patient had an antecedent of no light perception in his left eye secondary to retinal detachment treated in another health centre. He consulted with a history of blunt trauma in his head with an unremarkable anterior segment and fundus exam. Scleral indentation showed no lesions to be treated in the right eye. We recommended follow-up every six months. The patient did not come to controls. He was consulted three years later because of visual loss in his right eye. Fundus showed a total retinal detachment secondary to a giant retinal tear of 320o with macular involvement and choroidal detachments. Therefore, scleral buckling, lensectomy, pars plana vitrectomy, inferior retinectomy, endovenous laser treatment (endolaser), and silicone oil tamponade were performed. After six weeks of follow-up, the patient presented an inferior re-detachment with grade C3 vitreoretinal proliferation. A new procedure of silicone oil removal, epiretinal membrane removal, enlargement of inferior retinectomy, endolaser, and silicone oil tamponade was indicated. After 6-months of follow-up, no new retinal detachment was presented, and the best-corrected visual acuity was 20/100.

Choroidal and peripapillary changes in high myopic eyes with Stickler syndrome

BackgroundTo compare different clinical and Spectral-Domain Optical Coherence Tomography (SD-OCT) features of high myopic eyes with Stickler syndrome (STL) with matched controls.MethodsPatients with genetically confirmed STL with axial length ≥ 26 mm and controls matched for axial length were included. The following data were obtained from SD-OCT scans and fundus photography: choroidal and retinal thickness (respectively, CT and RT), peripapillary atrophy area (PAA), presence of posterior staphyloma (PS).ResultsTwenty-six eyes of 17 patients with STL and 25 eyes of 19 controls were evaluated. Compared with controls, patients with STL showed a greater CT subfoveally, at 1000 μm from the fovea at both nasal and temporal location, and at 2000 and 3000 μm from the fovea in nasal location (respectively, 188.7±72.8 vs 126.0±88.7 μm, 172.5±77.7 vs 119.3±80.6 μm, 190.1±71.9 vs 134.9±79.7 μm, 141.3±56.0 vs 98.1±68.5 μm, and 110.9±51.0 vs 67.6±50.7 μm, always P< 0.05). Furthermore, patients with STL showed a lower prevalence of PS (11.5% vs 68%, P< 0.001) and a lower PAA (2.2±2.1 vs 5.4±5.8 mm2, P=0.03), compared with controls.ConclusionsThis study shows that high myopic patients with STL show a greater CT, a lower PAA and a lower prevalence of PS, compared with controls matched for axial length. These findings could be relevant for the development and progression of myopic maculopathy in patients with STL.

‘Failure’ of laser prophylaxis in an eye with stickler syndrome

Background: Stickler syndrome is one of the most common inherited connective tissue disorders and is an important cause of pediatric vision loss due to a high risk of retinal detachment in these patients. Methods: Case report. Case summary: This case reports describes the clinical course of a 10 year old boy with Sticklers Syndrome who underwent bilateral peripheral laser prophylaxis. During routine follow up, he was found to have an asymptomatic giant retinal tear (GRT) with limited sub-retinal fluid expansion due to prior prophylactic laser. He underwent surgery with vitrectomy and scleral buckle with vision remaining at 20/25 at 6 month follow up. Conclusion: Although the utility of laser prophylaxis in Stickler patients is debated, this case demonstrates that after laser prophylaxis, even if GRT develops, expansion can be limited. Laser prophylaxis along with frequent examinations, can prevent development of PVR and complex detachments and preserve macular function with excellent visual outcome.

Progressive Visual Loss Without Retinal Detachment in Stickler Syndrome: An Uncommon and Novel Presentation

Stickler syndrome is known to cause visual handicap due to the high incidence of retinal detachment. We aim to present an unusual case of a child with Stickler syndrome who had progressive visual loss secondary to atrophy of the outer retinal layers not associated with retinal detachment. This is a descriptive case report of a 9-year-old child with ocular history of high myopia who presented to our institution with suboptimal visual acuity in both eyes. After 2 years of follow up, he developed unilateral progressive visual loss with marked atrophy of the outer retinal layers and peripheral vascular leakage. Such a presentation has not been previously described in the literature to the best of our knowledge.

Регматогенная отслойка сетчатки у детей

Purpose. To study the etiological structure of rhegmatogenous retinal detachment, the efficacy and outcomes of its surgical treatment in pediatric practice. Material and Methods. A retrospective series of cases in one vitreoretinal center in 2015–2019 was presented. The age of the children with rhegmatogenous retinal detachment (57 patients / 66 eyes) was from 0 to 18. Surgical treatment included vitreoretinal and scleral buckling techniques. Results. Rhegmatogenous retinal detachment in 30.3% of cases developed against the background of ROP, in 24.2% – against the background of Stickler‘s syndrome, in 12.1% – against the background of myopia, in 12.1% – against the background of trauma, and in 21.3 % – against the background of other reasons. On average, the anatomical treatment efficacy was 77.4%. The leading factors of an unfavorable outcome of treatment were the duration of presence of retinal detachment (OR 21.44; CI 3.76– 122.16) and 3–5 stages ROP (OR 2.56; CI 0.76–8.44). Visual acuity exceeding the blindness threshold (Vis &gt; 0.02) was maintained or achieved in 72% of cases. Conclusions. The specificity of the clinical course and adherence to surgical treatment of children with rhegmatogenous retinal detachment is determined by its etiology. Key words: retinal detachment in children, Stickler syndrome, retinopathy of prematurity, scleral buckling, vitreoretinal surgery.

Complex Phenotypic Presentation of Syndromic Hearing Loss Deciphered as Three Separate Clinical Entities: How Genetic Testing Guides Final Diagnosis

Background: Genetically determined prelingual hearing loss (HL) may occur in an isolated or syndromic form. Objective: The aim of the study was to unravel the genetic cause of medical problems in a 21-year-old woman, whose phenotypic presentation extended beyond Stickler syndrome and included enlarged vestibular aqueduct (EVA) and persistent microhematuria. Methods and Results: After sequencing of clinical exome, a known de novo COL2A1 pathogenic variant (c.1833+1G>A, p.?) causative for Stickler syndrome and one paternally inherited pathogenic change in COL4A5 (c.1871G>A, p.Gly624Asp) causative for X-linked Alport syndrome were found. No pathogenic variants, including those within the SLC26A4 5′ region (Caucasian EVA haplotype), explaining the development of EVA, were identified. Conclusions: The study reveals a multilocus genomic variation in one individual and provides a molecular diagnosis of two HL syndromes that co-occur in the proband independent of each other. For the third entity, EVA, no etiological factor was identified. Our data emphasize the relevance of detailed clinical phenotyping for accurate genotype interpretation. Focus on broadening the phenotypic spectrum of known genetic syndromes may actually obscure patients with multiple molecular diagnoses.

High Myopia and Strabismus Induced by a Deep Intronic Mutation in COL2A1

ABSTRACT Purpose: To characterize a genetic mutation causing Stickler syndrome in a previously undiagnosed family. Methods: Five generations of a single family suspected of having Stickler syndrome were evaluated clinically and genetically. Results: The demographic and clinical data yielded specific clinical phenotypes of Stickler syndrome in 13 family members; 7 had more than one clinical feature. Four family members underwent genetic analysis: the proband (index patient) and his mother, maternal grandfather, and healthy father. No relevant mutation was detected in the proband on whole exome analysis, but subsequent extension of the analysis to intronic areas yielded a deep intronic mutation, NM_001844.5:c.1527 + 135 G > A. Sanger sequencing was used to validate the results in the family members. Conclusions: Stickler syndrome has several subtypes with variable clinical features. Therefore, predicting the genetic locus of the disease based on clinical characteristics is challenging. We present a rarely described intronic mutation in COL2A1. Genetic testing may aid in the early diagnosis of Stickler syndrome, which is important for genetic counselling, proper clinical management, and improved prognosis.

Basedow-Graves\u2019 disease in a pediatric patient with Sticlker syndrome, a new endocrine finding to improve personalized treatment

BackgroundStickler syndrome is a connective tissue disorder with predominantly autosomal dominant inheritance, with ocular, auditory and joint involvement.Thyroid dysfunction was not described as part of alterations in Stickler syndrome and in particular, the association between Stickler’s syndrome and Graves’ disease has never been previously reported in literature.Moreover, the presence of Graves’ disease is uncommon in the pediatric age (especially in children younger than 6 years old).Case presentationWe report the case of a 5-years old child affected by Stickler syndrome who received the diagnosis of Graves’s disease, in absence of suggestive symptoms, during health supervision.ConclusionsThis is the first evidence of thyroid dysfunction and autoimmune pattern for Sticker syndrome.Further clinical reports are expected before suggesting the implementation of new clinical skills for Stickler syndrome, but this paper may contribute to improve personalized management of this rare disorder.

Long-Term Follow-Up of Retinal Detachment Repair in Patients With Stickler Syndrome.

To report the long-term anatomic and visual outcomes of patients with Stickler syndrome undergoing retinal detachment (RD) surgery. Retrospective, interventional, consecutive case series of patients with Stickler syndrome undergoing RD repair from 1999 to 2017 at the Long Island Vitreoretinal Consultants, New York. Retinal attachment status and visual acuity (VA) at 1-year and last follow-up were assessed. Successful reattachment was achieved in 28 of 29 eyes (97%) with an average of 2.3 surgeries (including silicone oil removal surgeries). Redetachment after the first surgery occurred in 13 eyes (45%). Mean Snellen VA at initial presentation, 1-year follow-up, and last follow-up were 20/289, 20/118 (P = .012), and 20/103 (P = .022), respectively. Anatomic success can be achieved in most eyes. However, redetachments are common, and multiple surgeries are often required. Reasonable visual recovery is possible in many eyes. [Ophthalmic Surg Lasers Imaging Retina. 2020;51:612-616.].

Long-Term Orthognathic Considerations in the Pierre Robin Sequence Patient.

One of the arguments against early intervention for micrognathia in Pierre Robin sequence is the concept that the growth of the mandible will eventually "catch up." Long-term growth of the mandible and occlusal relationships of conservatively managed Pierre Robin sequence patients remain unknown. In this study, the authors evaluated the orthognathic surgery requirements for Pierre Robin sequence patients at skeletal maturity. Orthognathic surgical requirements of conservatively managed Pierre Robin sequence and isolated cleft patients (aged ≥13 years) at two institutions were reviewed and analyzed using t test, chi-square test, and Fisher's exact test. Values of p < 0.05 were considered statistically significant. Of the Pierre Robin sequence patients (n = 64; mean age ± SD, 17.9 ± 2.9 years), 65.6 percent were syndromic (primarily Stickler and velocardiofacial syndrome), 96.9 percent had a cleft palate, and 39.1 percent required orthognathic surgery at skeletal maturity. Nonsyndromic and syndromic Pierre Robin sequence patients demonstrated no differences in occlusal relationships or mandibular surgery frequency. The majority of Pierre Robin sequence patients requiring mandibular advancement had a class II occlusion. Comparison of Pierre Robin sequence patients to isolated cleft palate patients (n = 17) revealed a comparable frequency of orthognathic surgery between the two; however, Pierre Robin sequence patients did require mandibular advancement surgery at a greater frequency than cleft palate patients (p = 0.006). The present study found that 39.1 percent of conservatively managed Pierre Robin sequence patients required orthognathic surgery at skeletal maturity, of which the vast majority required mandibular advancement for class II malocclusion. These data suggest that mandibular micrognathia in conservatively managed Pierre Robin sequence patients may not resolve over time and may require surgical intervention. Risk, II.

Auditory dysfunction in type 2 Stickler Syndrome

PurposeTo present the extent and site of lesion of auditory dysfunction in a large cohort of individuals with type 2 Stickler Syndrome. Type 2 Stickler Syndrome results from a mutation in the gene coding for α-1 type XI pro-collagen, which has been identified in the human vitreous, cartilage and the cochlea of the mouse. The condition is characterised by classic ocular abnormalities, auditory dysfunction, osteoarthropathy and oro-facial dysplasia.MethodsThis is a population study which used a combination of audiometric, tympanometric, and self-report measures on a series of 65 individuals (mean age 29.2 years, range 3–70, female 63.1%) with genetically confirmed type 2 Stickler Syndrome.ResultsHearing impairment was identified in at least one ear for 69% of individuals. Analysis against age-matched normative data showed that reduced hearing sensitivity was present across all test frequencies. Sensorineural hearing loss was most common (77% of ears), with conductive (3%), mixed (7%) and no hearing loss (13%), respectively. The proportion of hypermobile tympanic membranes (24%) was less than previously documented in type 1 Stickler Syndrome. When present, this appears to arise as a direct result of collagen abnormalities in the middle ear. Self-report measures of speech and spatial hearing in sound were comparable to a non-syndromic cohort with similar audiometric thresholds.ConclusionsAuditory impairment in type 2 Stickler Syndrome is predominantly associated with cochlear hearing loss of varying severities across affected individuals. The impact on hearing thresholds can be seen across the frequency range, suggesting a contribution of defective collagen throughout the cochlea. Self-report questionnaires showed that difficulties understanding speech, and spatial information in sound (such as that used for localisation), were worse than a young, normal-hearing population but comparable to a non-syndromic cohort with similar audiometric thresholds. Therefore, it is likely that hearing loss in type 2 Stickler Syndrome arises in the auditory periphery, without significant central processing deficits.

Stickler Syndrome: A Review of Clinical Manifestations and the Genetics Evaluation.

Stickler Syndrome (SS) is a multisystem collagenopathy frequently encountered by ophthalmologists due to the high rate of ocular complications. Affected individuals are at significantly increased risk for retinal detachment and blindness, and early detection and diagnosis are critical in improving visual outcomes for these patients. Systemic findings are also common, with craniofacial, skeletal, and auditory systems often involved. SS is genotypically and phenotypically heterogenous, which can make recognizing and correctly diagnosing individuals difficult. Molecular genetic testing should be considered in all individuals with suspected SS, as diagnosis not only assists in treatment and management of the patient but may also help identify other at-risk family members. Here we review common clinical manifestation of SS and genetic tests frequently ordered as part of the SS evaluation.

Clinical genetics, practice, and research of deafblindness: From uncollected experiences to the national registry in Japan

Deafblindness is a condition of combined vision and hearing loss that is extremely rare in children and young adults, as well as being a highly heterogeneous condition, with over 70 specific etiologies. Due to these features, sporadic clinical experiences have not been collated, which has hampered medical progress. Genetics plays a major role in the pathogenesis of deafblindness in children and young adults, with more than 50 hereditary syndromes and disorders associated with the condition, including CHARGE, Usher, Down, Stickler, and Dandy-Walker syndromes, which are the most common. Clinical diagnosis of deafblindness is often difficult, and a significant proportion of patients are undiagnosed. No curative therapy is currently available for the majority of patients with hereditary deafblindness; however, experimental studies using animal models have shown promising results by targeting specific genes that cause vision or hearing loss. In Japan, the Rare Disease Data Registry of Japan (RADDAR-J) has been established as a national registry of rare and intractable diseases. Diseases of deafblindness have been elected as a disease category in RADDAR-J. Currently, clinical and genomic data are being collected and analyzed using this system, with the aim of generating an overview of deafblindness to improve medical practice.