retinal detachments

Spondyloocular Syndrome

Clinical Characteristics
Ocular Features: 

Cataracts have been noted in several patients in the first and second decades of life.  Nystagmus and ‘amblyopia’ have also been reported.  Several individuals have had retinal detachments.

Systemic Features: 

Only a small number of families have been reported.  Poor bone mineralization with frequent fractures in long bones and vertebral compression seem to be consistent features often noted in the first and second decades of life.  Moderate osteoporosis and advanced bone age with platyspondyly may be present.  The vertebral fractures lead to abnormal spinal curvature and may result in shortened stature. 

Some sensorineural hearing loss is sometimes detected in the first decade.  The ears have been described as low-set and posteriorly rotated.  A variety of cardiac defects have been reported including mitral valve prolapse, septal defects, and anomalies of the aortic valve. 

Genetics

This is an autosomal recessive disorder secondary to homozygous mutations in the XYLT2 gene located at 17q21.33. 

Pedigree: 
Autosomal recessive
Treatment
Treatment Options: 

Pamidronate given intravenously seems to have little therapeutic value.  Hearing aids can be beneficial.  Lensectomy may be of benefit although no reports of cataract surgery have been reported.  Fractures need immediate attention.  Patient may become wheelchair-bound by the second decade.  Special education may be helpful for those with learning difficulties.

References
Article Title: 

Myopia 2, Autosomal Dominant, Nonsyndromal

Clinical Characteristics
Ocular Features: 

Nonsyndromal, high myopia (over 6 D) has been found in multiple multigenerational families.  Most individuals have no other ocular problems but a small percentage develop degenerative changes in the retina, particularly in the macula (Fuchs spot).  A few individuals have posterior staphylomas with significant vitreoretinal changes conferring higher risks of retinal detachments and macular holes.  Vitreous traction is often present.  The macula in such cases is may be thickened and microcystic with areas of frank retinoschisis.  Of course, vitreous degeneration and retinal detachments are well known sequelae of high myopia. 

Systemic Features: 

There are no systemic features by definition. 

Genetics

Refractive errors are continuous traits with a wide range in most populations.  This suggests that many developmental and heritable (and perhaps environmental) components are responsible.  No specific mutation has been identified but a number of 'susceptibility' loci have been mapped.

Myopia 2 has been linked to a susceptibility locus at 18q11.31.

Evidence of heritability in both syndromal and isolated myopia comes from several sources.  For example, high myopia is a common feature in familial collagenopathies such as Marfan syndrome (154700), Kniest dysplasia (156550), and Stickler syndrome (108300). Multigenerational families with isolated myopia have been reported as well and mutations in multiple genes (at least 18) have been associated with these.  Heredibility studies using twin pairs have identified additional mutations (609256).  Further, the prevalence of myopia among children increases in the presence of parental myopia.

The transmission pattern in most families to which susceptibility loci have been linked is autosomal dominant.  However, a susceptibility locus has been mapped to 14q22.1-q24.2 in several families with good evidence for autosomal recessive inheritance (255500).  In addition, two loci on the X chromosome have been linked to presumed X-linked myopia (MYP1 [310460] at Xq28 and MYP13 [300613] at Xq23-q25).  A patient with high myopia has been reported with a mutation in the NYX gene on the X-chromosome.  This patient did not have congenital stationary night blindness of the type CSNB1A (310500) in which NYX is usually mutated.

Pedigree: 
Autosomal dominant
Treatment
Treatment Options: 

Correction of the refractive error is primary.  High myopes require periodic evaluation throughout life and prompt surgical intervention for retinal detachments.  In extreme myopia it may be especially prudent for individuals to avoid impact sports. 

References
Article Title: 

Spondyloepiphyseal Dysplasia Congenita

Clinical Characteristics
Ocular Features: 

Patients characteristically have vitreous abnormalities described as veils or stands.  The central vitreous may undergo liquefaction and the peripheral vitreous sometimes creates traction on the retina.  High myopia with progression is common and a significant proportion of patients suffer detachments of the retina even in the absence of myopia.  Lattice degeneration is frequently seen.  Most patients have 20/50 or better vision.

Systemic Features: 

Dwarfism with kyphosis and a barrel chest are characteristic.  The vertebrae are often flattened and malformed and the neck is short.  Delayed ossification in the epiphyses and the os pubis is common.  The disorder can be evident at birth but the full syndrome may not be evident until 3 or 4 years of age.  Radiologic studies are important in making the diagnosis.

Genetics

This is generally considered an autosomal dominant disorder secondary to mutations in the COL2A1 gene impacting type II collagen.  This type of collagen is found primarily in cartilage and vitreous and a number of type II collagenopathy disorders are associated with vitreoretinopathy and joint disease of which Stickler syndrome type I (609508, 108300) is the most common.  Other disorders in this database caused by mutations in COL2A1 are: Kniest dysplasia (156550), Stickler syndromes type I (609508, 108300 ) and II (604841), vitreoretinopathy with epiphyseal dysplasia (120140), and spondyloepiphyseal dysplasia congenita (183900).

Pedigree: 
Autosomal dominant
Treatment
Treatment Options: 

Cervical fusion is sometimes used when odontoid hypoplasia leads to hypermobility of the cervical vertebrae.  Retinal detachments, of course, need to be repaired.

References
Article Title: 

Wagner Syndrome

Clinical Characteristics
Ocular Features: 

This is one of several hereditary vitreoretinal degenerative disorders in which vitreous degeneration occurs and the risk of retinal detachment is high (others being Goldmann-Favre [268100], Stickler [609508, 108300], and Marshall [154780] syndromes).  An optically empty central vitreous is a common feature in this heterogeneous group.  Other reported ocular findings in Wagner syndrome include perivascular sheathing and pigmentation, progressive chorioretinal dystrophy, ectopic fovea with pseudoexotropia, tractional retinal detachments, glaucoma (neovascular in some), and vitreous veils with fibrillar condensation.  Cataracts occur in virtually all patients over the age of 45 years.  The ERG in the majority of patients shows elevated rod and cone thresholds on dark adaptation (63%) and subnormal b-wave amplitudes (87%).  Mild difficulties in dim light are noted by some patients.  Visual acuities are highly variable ranging from normal in many patients to blindness in others.  Peripheral visual fields may be severely constricted.

Systemic Features: 

Cleft palate has been seen in some patients but these likely had Stickler syndrome (609508, 108300, 604841 ) since hearing loss along with other joint and skeletal manifestations are absent.  Further, cases reported to have Wagner syndrome with palatoschisis have not been genotyped so it is likely that they were misdiagnosed.

Genetics

Wagner syndrome results from a mutation in the VCAN gene encoding versican (5q14.3), a chondroitin sulfate proteoglycan-2 found in the vitreous among other tissues.  It is an autosomal dominant disorder.  It has been proposed that erosive vitreoretinopathy (ERVR) (143200) is allelic to Wagner’s syndrome but it may also simply be a variable expression of the same disorder.  Both map to 5q13-q14.  Overlapping of clinical signs and symptoms among hereditary disorders of vitreoretinal degeneration has created some confusion in their classification but this will hopefully be clarified as more families are genotyped.  Stickler syndrome (609508, 108300), for example, is known to be caused by a mutation in an entirely different gene (COL2A1) on a different chromosome.

Snowflake type vitreoretinal degeneration (193230), another autosomal dominant disorder, has a superficial resemblance but mutations in a different gene (KCNJ13) are responsible.

Pedigree: 
Autosomal dominant
Treatment
Treatment Options: 

There is no therapy specifically for this disorder but the usual treatments for retinal detachments, cataract and glaucoma should be applied where appropriate.

References
Article Title: 

Stickler Syndrome, Type I

Clinical Characteristics
Ocular Features: 

High myopia and vitreous degeneration dominate the ocular manifestations of Stickler syndrome, type I.  The vitreous often appears optically empty as it liquefies and the fibrils degenerate.  The vitreous is sometimes seen to form 'veils', especially in the retrolenticular region but they may also float throughout the posterior chamber.  They are often attached to areas of lattice degeneration in the retina as well as other areas.  Posterior vitreous detachments are common.  Vitreoretinal degeneration is progressive and by the second decade rhegmatogenous detachments occur in half of affected patients.  As many as three quarters of adult patients have retinal breaks.  The retina has pigmentary changes with deposition circumferentially near the equator and more peripherally.  Hypopigmentation is more common early creating a tessellated appearance.  Lenticular opacities occur also early with cortical flecks and wedge-shaped changes.

The ERG may be normal early but evidence of rod and cone dysfunction soon appears and is progressive.  Dark adaptation is defective later in the course of the disease.  The EOG is virtually always depressed.  The visual field is constricted and may show a ring scotoma coincident with the equatorial chorioretinal atrophy.

Glaucoma is not uncommon and may be infantile in onset and difficult to control.  

Phthisis is a significant risk especially for individuals who have multiple surgical procedures for retinal detachments. 

Systemic Features: 

It has been suggested that there is a nonsyndromic or ocular type of Stickler syndrome lacking many of the extraocular features characteristic of the complete syndrome.  However, the evidence for the ocular type described here as a distinct entity remains slim and the clinical picture may simply reflect variable expressivity of mutations in the same gene.  Type I Stickler syndrome has multiple systemic features such as cleft palate, hearing impairment, premature arthritis, micrognathia, kyphoscoliosis, and some signs such as arachnodactyly that are found in the Marfan syndrome.

Genetics

This is an autosomal dominant disease of collagen formation as a result of mutations in the COL2A1 gene (12q13.11-q13.2). The mutations causing both syndromal and the suggested nonsyndromal ocular type of Stickler disease are in the same gene.  Mutations in the same gene are known to cause autosomal dominant rhegmatogenous retinal detachments in patients who have none of the systemic clinical signs (609508).  These patients may lack the signs of vitreous degeneration seen in Kniest dysplasia (156550)  and in the disorder described here.

There is better evidence for a second type of Stickler syndrome, STL2 or type II (604841) based on phenotypic differences and the fact that a second locus (1p21) containing mutations in COL11A1 has been linked to it. 

Type III is caused by mutations in COL11A2 and has systemic features similar to types I and II but lacks the eye findings since this gene is not expressed in the eye.

Type IV also has important ocular features but is an autosomal recessive disorder caused by mutations in COL9A2.

Pedigree: 
Autosomal dominant
Treatment
Treatment Options: 

The combination of progressive vitreoretinal degeneration, frequency of posterior vitreous detachments, and axial myopia creates a lifelong threat of retinal tears and detachments.   Half to three quarters of all patients develop retinal tears and detachments.  Certainly all patients with Stickler syndrome deserve repeated and thorough retinal exams throughout their lives.  In addition to prompt treatment of tears and detachments, some have advocated prophylactic scleral banding to reduce vitreous traction, or applying 360 degree cryotherapy.

References
Article Title: 

Stickler syndrome in children: a radiological review

McArthur N, Rehm A, Shenker N, Richards AJ, McNinch AM, Poulson AV, Tanner J, Snead MP, Bearcroft PWP. Stickler syndrome in children: a radiological review. Clin Radiol. 2018 Apr 13. pii: S0009-9260(18)30118-1. doi: 10.1016/j.crad.2018.03.004. [Epub ahead of print].

PubMed ID: 
29661559

High efficiency of mutation detection in type 1 stickler syndrome using a two-stage approach: vitreoretinal assessment coupled with exon sequencing for screening COL2A1

Richards AJ, Laidlaw M, Whittaker J, Treacy B, Rai H, Bearcroft P, Baguley DM, Poulson A, Ang A, Scott JD, Snead MP. High efficiency of mutation detection in type 1 stickler syndrome using a two-stage approach: vitreoretinal assessment coupled with exon sequencing for screening COL2A1. Hum Mutat. 2006 Jul;27(7):696-704. Erratum in: Hum Mutat. 2006 Nov;27(11):1156.

PubMed ID: 
16752401
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