Stickler Syndrome

Stickler syndrome is a genetic condition that affects the body's connective tissue, which is the material that provides strength and support to many different organs and systems. Because connective tissue is found throughout the body, Stickler syndrome can cause a wide variety of symptoms, most commonly affecting the eyes, ears, joints, and facial structure. The condition is usually passed down through families, but the severity of symptoms can vary greatly even among family members. For the eyes, Stickler syndrome often causes severe nearsightedness (myopia) that is present from a very young age. The most serious eye complication is a high risk of retinal detachment, where the light-sensitive layer at the back of the eye pulls away, which can lead to vision loss or blindness if not treated quickly. Patients may also develop cataracts or glaucoma earlier in life than usual. Other common features of the syndrome include hearing loss, a flattened facial appearance, cleft palate, and joint problems such as hypermobility in childhood followed by early-onset arthritis in adulthood. While there is no cure for Stickler syndrome, many of its complications can be managed or prevented with early diagnosis and regular medical care. It is crucial for individuals with Stickler syndrome to have frequent, thorough eye exams so that any signs of retinal tearing can be treated preventatively, often with a laser procedure. A team of specialists, including eye doctors, audiologists, and rheumatologists, can help manage the various symptoms and maintain a good quality of life.

Condition category: Syndromic IRD

Prevalence: 1 in 7,500 - 9,000

Inheritance patterns: Autosomal Dominant, Autosomal Recessive

Age of onset: Congenital to early childhood (often detectable at birth or early adolescence)

Clinical overview: Stickler syndrome is a clinically variable and genetically heterogeneous connective tissue disorder characterized by ophthalmic, auditory, orofacial, and articular manifestations. First described in 1965, it is one of the most common inherited connective tissue disorders. The condition is primarily classified into several subtypes based on the specific collagen gene mutated and the resulting clinical phenotype, particularly the appearance of the vitreous anomaly. The clinical significance of Stickler syndrome lies in its multisystem involvement and the high risk of severe complications, most notably rhegmatogenous retinal detachment, which can lead to blindness if not promptly treated. Other key features include high myopia, early-onset cataracts, sensorineural hearing loss, craniofacial abnormalities such as Pierre Robin sequence (micrognathia, glossoptosis, cleft palate), and precocious osteoarthritis. Due to its variable expressivity, Stickler syndrome is often underdiagnosed. Early recognition is crucial for implementing prophylactic measures, such as laser retinopexy, to prevent retinal detachment, and for providing appropriate multidisciplinary management for hearing, skeletal, and craniofacial issues. The condition is cataloged under several OMIM numbers, including 108300 (Type I), 604841 (Type II), 609508 (Type I, ocular-only), 614134 (Type IV), 614284 (Type V), and 620022 (Type VI), and Orphanet number ORPHA:828.

Patient and family guide: Stickler syndrome is a genetic condition that affects the body's connective tissue, which is the material that provides strength and support to many different organs and systems. Because connective tissue is found throughout the body, Stickler syndrome can cause a wide variety of symptoms, most commonly affecting the eyes, ears, joints, and facial structure. The condition is usually passed down through families, but the severity of symptoms can vary greatly even among family members. For the eyes, Stickler syndrome often causes severe nearsightedness (myopia) that is present from a very young age. The most serious eye complication is a high risk of retinal detachment, where the light-sensitive layer at the back of the eye pulls away, which can lead to vision loss or blindness if not treated quickly. Patients may also develop cataracts or glaucoma earlier in life than usual. Other common features of the syndrome include hearing loss, a flattened facial appearance, cleft palate, and joint problems such as hypermobility in childhood followed by early-onset arthritis in adulthood. While there is no cure for Stickler syndrome, many of its complications can be managed or prevented with early diagnosis and regular medical care. It is crucial for individuals with Stickler syndrome to have frequent, thorough eye exams so that any signs of retinal tearing can be treated preventatively, often with a laser procedure. A team of specialists, including eye doctors, audiologists, and rheumatologists, can help manage the various symptoms and maintain a good quality of life.

Symptoms and clinical features: The clinical presentation of Stickler syndrome is highly variable and involves multiple organ systems. In the early stages (infancy and childhood), craniofacial abnormalities are often the most apparent. These can include a flattened facial profile (midface hypoplasia), a small jaw (micrognathia), and cleft palate, which may present as Pierre Robin sequence. Ocular symptoms typically begin with congenital high myopia. Joint hypermobility is common in childhood, and mild sensorineural or conductive hearing loss may be detected. During the intermediate stages (adolescence to young adulthood), the risk of severe ocular complications increases significantly. Patients may experience floaters or flashes of light, which are warning signs of retinal tears or detachment. The characteristic vitreous anomalies (membranous or beaded) become more apparent on examination. Joint hypermobility often transitions to joint stiffness and pain, marking the onset of precocious osteoarthritis. Hearing loss may progress, particularly in certain genetic subtypes. In the advanced stages (adulthood), chronic musculoskeletal issues often dominate the clinical picture, with severe osteoarthritis frequently requiring surgical intervention, such as joint replacements, in the third or fourth decade. Spinal abnormalities like scoliosis or kyphosis can cause chronic back pain. Ocular issues continue to be a major concern, with an increased risk of developing early-onset cataracts and, less commonly, glaucoma. Vision loss may occur if retinal detachments are recurrent or unsuccessfully repaired.

Molecular pathology: Stickler syndrome is fundamentally a collagenopathy, caused by defects in the genes encoding types II, IX, and XI collagen. These collagens are crucial structural components of the extracellular matrix in various connective tissues, including the vitreous humor of the eye, articular cartilage in joints, the inner ear, and craniofacial structures. Type II collagen is the most abundant fibrillar collagen in these tissues, while types IX and XI collagens play essential roles in regulating the size, spacing, and cross-linking of the type II collagen fibrils. Mutations in the associated genes (COL2A1, COL11A1, COL11A2, COL9A1, COL9A2, COL9A3) lead to the production of abnormal collagen chains or a reduction in the total amount of normal collagen. This disrupts the intricate architecture of the collagen fibril network. In the eye, this defective extracellular matrix leads to abnormal vitreous gel formation, causing it to liquefy and collapse prematurely. This altered vitreous structure exerts abnormal traction on the retina, significantly increasing the risk of retinal tears and detachment. In the skeletal system, the defective collagen network compromises the structural integrity and shock-absorbing capacity of articular cartilage, leading to premature wear and tear and early-onset osteoarthritis. In the inner ear, the exact mechanism is less clear but likely involves structural defects in the collagen-rich structures essential for sound transduction, resulting in sensorineural hearing loss. The craniofacial abnormalities, such as midface hypoplasia and cleft palate, arise from defective cartilage formation during embryonic development.

Genetics: Stickler syndrome is genetically heterogeneous, with both autosomal dominant and autosomal recessive inheritance patterns. The most common forms, types 1, 2, and 3, are inherited in an autosomal dominant manner and are caused by heterozygous mutations in the COL2A1, COL11A1, and COL11A2 genes, respectively. Type 1 (STL1) accounts for 80-90% of cases. Autosomal recessive forms (types 4, 5, and 6) are much rarer and are caused by biallelic mutations in the COL9A1, COL9A2, and COL9A3 genes. Genotype-phenotype correlations exist but can be complex due to significant inter- and intrafamilial variability. COL2A1 mutations typically cause the classic type 1 phenotype with membranous vitreous and a high risk of retinal detachment. Interestingly, mutations specifically in exon 2 of COL2A1 often result in an ocular-only phenotype. COL11A1 mutations (type 2) are associated with a beaded vitreous phenotype, more severe hearing loss, and a higher incidence of cataracts. COL11A2 mutations (type 3) cause a non-ocular form of the syndrome, as this gene is not expressed in the eye. The known causative genes for Stickler syndrome include COL2A1, COL11A1, COL11A2, COL9A1, COL9A2, and COL9A3. Mutations in these genes typically lead to haploinsufficiency or exert a dominant-negative effect, disrupting the normal assembly of collagen fibrils essential for connective tissue integrity.

Diagnostic evaluation: Clinical diagnosis of Stickler syndrome is based on a combination of ocular, auditory, craniofacial, and skeletal findings, often utilizing the Rose et al. diagnostic criteria. A comprehensive clinical workup includes a detailed ophthalmologic examination, audiometry, and skeletal imaging. Fundoscopy and slit-lamp biomicroscopy are critical for identifying characteristic vitreous anomalies (membranous in type 1, beaded in type 2), high myopia, and retinal changes such as lattice degeneration or retinal tears. Optical coherence tomography (OCT) may be used to assess macular anatomy and detect subtle retinal changes. Electrophysiology, such as electroretinography (ERG), is generally not the primary diagnostic tool for Stickler syndrome, as the condition is primarily a vitreoretinopathy rather than a primary photoreceptor dystrophy, though it may be used to rule out other inherited retinal diseases. Visual field testing can help monitor for peripheral vision loss associated with retinal detachment or glaucoma. Molecular genetic testing is the definitive method for confirming the diagnosis and determining the specific subtype. A multigene panel including COL2A1, COL11A1, COL11A2, COL9A1, COL9A2, and COL9A3 is typically employed. Differential diagnosis includes other connective tissue disorders and vitreoretinopathies such as Marfan syndrome (distinguished by ectopia lentis), Ehlers-Danlos syndromes, Wagner syndrome (typically lacks systemic features), Kniest dysplasia, and Marshall syndrome.

Differential diagnosis: Differential diagnosis of Stickler syndrome includes: (1) Marshall syndrome — similar craniofacial features but shorter stature, thickened calvaria; COL11A1 mutations. (2) Wagner syndrome — vitreoretinal degeneration without systemic features; VCAN mutations. (3) Kniest dysplasia — more severe skeletal dysplasia, dumbbell-shaped femora; COL2A1 mutations. (4) Spondyloepiphyseal dysplasia congenita — short trunk, myopia, retinal detachment; COL2A1 mutations. (5) Marfan syndrome — tall stature, lens subluxation, aortic root dilation; FBN1 mutations. (6) Ehlers-Danlos syndrome — joint hypermobility, skin hyperextensibility; various collagen gene mutations. (7) Pierre Robin sequence — micrognathia, glossoptosis, cleft palate without vitreoretinal pathology.

Natural history: The natural history of Stickler syndrome is characterized by a progressive course of multisystem involvement, though the severity and age of onset vary widely. Ocular manifestations, particularly high myopia, are often congenital or develop in early childhood. The risk of retinal detachment is a lifelong concern, with the peak incidence occurring between the ages of 10 and 30 years, especially in type 1. Without prophylactic intervention, retinal detachment can lead to rapid and severe visual decline. Hearing loss, typically sensorineural, may be present in childhood and can be progressive, particularly in type 2 Stickler syndrome. Conductive hearing loss may also occur, often secondary to recurrent otitis media associated with cleft palate. Skeletal manifestations often become apparent in childhood or adolescence with joint hypermobility, which typically transitions to joint stiffness and pain in adulthood. Early-onset osteoarthritis is a hallmark of the disease, frequently requiring joint replacement surgery in the third or fourth decade of life. Craniofacial features, such as midface hypoplasia, are most prominent in infancy and may become less noticeable as the child grows.

Management and treatment research: ### Current management and standard of care Stickler syndrome is managed by a multidisciplinary team, with care tailored to a person’s eye, hearing, joint, and craniofacial findings. There is no cure that corrects the underlying genetic cause. Ongoing monitoring and early treatment of complications are important. Protecting vision is a major priority because some people with Stickler syndrome have an increased risk of retinal tears, giant retinal tears, and retinal detachment. Regular examinations by an ophthalmologist or retinal specialist are particularly important for people with high myopia (severe nearsightedness), vitreous abnormalities, or a personal or family history of retinal detachment. New flashes of light, a sudden increase in floaters, or a curtain-like shadow in vision need urgent eye assessment. Management may include: - **Retinal-detachment prevention:** For selected people at high risk—especially those with type 1 Stickler syndrome—retinal specialists may discuss preventive treatment of the peripheral retina. Options can include 360-degree laser retinopexy or cryotherapy (freezing treatment), which aim to create stronger adhesion between the retina and the eye wall. The potential benefits and risks should be considered individually with an experienced retinal specialist. - **Retinal detachment repair:** If a detachment occurs, treatment may include scleral buckling, pars plana vitrectomy, laser treatment, or a combination of surgical approaches. - **Refractive and other eye care:** Glasses or contact lenses can correct myopia and other refractive errors. Cataracts and glaucoma, if present, are treated using standard medical or surgical care. - **Hearing and speech support:** Regular hearing assessments can identify hearing loss. Hearing aids and, for some people, cochlear implants may be options. Speech-language therapy may help children with cleft palate or hearing impairment. - **Craniofacial care:** Cleft palate repair and related care are generally coordinated through a specialized cleft palate or craniofacial team. - **Joint and mobility care:** Physical therapy, activity modification, pain management, and orthopedic care may help manage joint pain, hypermobility, and early osteoarthritis. Joint replacement may be considered for severe arthritis. ### Approved therapies There are no approved gene therapies, RNA-based therapies, or medicines specifically designed to treat Stickler syndrome itself. Current treatment focuses on monitoring, prevention of avoidable complications, and management of eye, hearing, craniofacial, and joint symptoms. ### Investigational research No disease-modifying gene therapy, RNA therapy, or drug treatment for Stickler syndrome is listed in the current treatment pipeline. #### Retinal detachment prevention A recruiting clinical study is evaluating preventive laser treatment for retinal detachment in Stickler syndrome: - **NCT07146516:** *Retinal Detachment Prevention (Laser Prophylaxis) in Stickler Syndrome (SS)* — recruiting. Preventive laser treatment targets the peripheral retina. It is not appropriate for every person with Stickler syndrome, and study participation does not replace regular retinal monitoring. #### Myopia management High myopia is common in Stickler syndrome. A recruiting study is evaluating optical devices intended to slow myopia progression: - **NCT07698977:** *Inhibition of Myopia Progression With Optical Devices* — recruiting. This study does not treat the genetic cause of Stickler syndrome or replace surveillance for retinal tears and detachment. ### Clinical trial participation Clinical trials and natural-history studies may help improve understanding of Stickler syndrome and evaluate approaches to prevention and care. Other currently listed studies include: - **NCT01793168:** *Rare Disease Patient Registry & Natural History Study - Coordination of Rare Diseases at Sanford* — recruiting. - **NCT03655223:** *Early Check: Expanded Screening in Newborns* — active, not recruiting. Eligibility may depend on age, genetic findings, eye features, location, and prior treatments. A retinal specialist or genetics team can help families discuss whether a study may be suitable.

Outlook: The overall prognosis for individuals with Stickler syndrome is generally good regarding life expectancy, which is not typically reduced. However, the condition can significantly impact the quality of life due to its multisystem complications. The visual prognosis depends heavily on the early detection and successful management of retinal detachments; prophylactic laser treatment has been shown to substantially reduce the risk of severe vision loss. Quality of life considerations include managing chronic joint pain and early-onset osteoarthritis, which may necessitate joint replacement surgeries at a relatively young age. Hearing loss, if progressive, requires ongoing audiological support and potentially hearing aids. Multidisciplinary care is essential to address the varied clinical manifestations and optimize functional outcomes for patients.

Epidemiology: Stickler syndrome is one of the most common inherited connective tissue disorders, with an estimated prevalence of 1 in 7,500 to 1 in 9,000 live births. However, it is widely believed that the condition is underdiagnosed or misdiagnosed due to its highly variable clinical presentation and the subtlety of symptoms in mild cases. The disorder affects individuals across all geographic and ethnic groups with no known predilection. There are no significant sex differences in the prevalence of Stickler syndrome, as the most common forms are inherited in an autosomal dominant manner.

Selected references: 1. Boothe M, Morris R, Robin N. Stickler Syndrome: A Review of Clinical Manifestations and the Genetics Evaluation. J Pers Med. 2020;10(3):105. PMID: 32867104 2. Snead MP, Yates JR. Clinical and Molecular genetics of Stickler syndrome. J Med Genet. 1999;36(5):353-359. PMID: 10353778 3. Rose PS, Ahn PN, Levy HP, et al. A syndrome of short stature, joint dysplasia, and deafness. Am J Med Genet A. 2005;138A(3):199-207. PMID: 16152640 4. Fincham GS, Pasea L, Carroll C, et al. Prevention of retinal detachment in Stickler syndrome: the Cambridge prophylactic cryotherapy protocol. Ophthalmology. 2014;121(8):1588-1597. PMID: 24793526 5. Khanna S, Gelman R, Williams P, et al. Laser Prophylaxis for Retinal Detachment in Stickler Syndrome. Ophthalmol Retina. 2022;6(4):263-267. PMID: 34653545 6. Nixon TRW, Richards AJ, Snead MP. Stickler Syndrome: An Update on Clinical and Molecular Genetics. Genes (Basel). 2022;13(7):1135. PMID: 35885918