autosomal dominant

Marshall Syndrome

Clinical Characteristics
Ocular Features: 

Myopia is a common feature.  The globes appear prominent with evident hypertelorism, perhaps in part due to shallow orbits.  The vitreous is abnormally fluid.  The beaded vitreous pattern seen in Stickler syndrome type II (604841), with which Marshall syndrome is sometimes confused, is not seen in Marshall syndrome, nor is the same frequency of retinal detachments.  Congenital or juvenile cataracts were present in Marshall’s original family.

Systemic Features: 

The midface is flat with some features of the Pierre-Robin phenotype.  The nasal root is flat and the nares anteverted.  Patients tend to be short in stature and joints are often stiff.  Small iliac wings and a thickened calvarium can be seen radiologically together with other bone deformities.  Abnormal frontal sinuses and intracranial calcifications have also been reported.  Sensorineural hearing loss may be noted during the first year of life with age-related progression.  Osteoarthritis of the knees and lumbosacral spine begins in the 4th and 5th decades.  Features of anhidrotic ectodermal dysplasia such as hypohidrosis and hypotrichosis are present in some patients.  Individuals may have linear areas of hyperpigmentation on the trunk and limbs.

Genetics

The syndromal status of Marshall syndrome as a unique entity remains uncertain inasmuch as there are many overlapping clinical features with Stickler syndrome type II (604841) and both result from mutations in the COL11A1 gene (1p21).  Autosomal dominant inheritance is common to both although autosomal recessive inheritance has been proposed for a few families with presumed Marshall syndrome. Stickler syndrome type II (604841) and Marshall syndrome may be allelic or even the same disorder.

Pedigree: 
Autosomal dominant
Autosomal recessive
Treatment
Treatment Options: 

No treatment is available for this disorder beyond cataract removal.  Patients need to be monitored for retinal breaks and detachments.

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: 

External Ophthalmoplegia, C10ORF2 and mtDNA Mutations

Clinical Characteristics
Ocular Features: 

Ptosis and external ophthalmoplegia are found in almost all patients.  These have a variable onset with some patients not symptomatic until midlife or later.  External ophthalmoplegia may be the only symptom.  Onset in late adolescence has also been reported.  Cataracts often occur.

Systemic Features: 

About half (52%) of patients have fatigue and weakness.  Ataxia and peripheral neuropathy with paresthesias are sometimes present. Some patients report bulbar symptoms of dysphagia, dysarthria and dysphonia.  Skeletal muscle biopsies show typical ragged red fibers and evidence of mitochondrial dysfunction with cytochrome c oxidase (COX) deficiency.  Late onset of typical features of parkinsonism including a resting tremor, rigidity, and bradykinesia is seen in some patients.  Several individuals have reported major depression and/or bipolar disorder. Myopathy (33%) with muscle wasting and respiratory difficulties can occur.   As many as 24% of patients have cardiac abnormalities consisting primarily of conduction defects.

Genetics

This an autosomal dominant disorder secondary to mutations in the C10ORF2 (Twinkle) gene (10q24) in association with mitochondrial DNA depletion.  It accounts for approximately 35% of autosomal dominant cases of external ophthalmoplegia.

At least two additional mutations cause similar external ophthalmoplegia syndromes: PEOA1 (157640, 258450), and PEOA2 (609283).

The same gene may have mutations that are responsible for spinocerebellar ataxia, infantile-onset (271245), a more generalized and progressive neurodegenerative disease transmitted in an autosomal recessive pattern.

Pedigree: 
Autosomal dominant
Treatment
Treatment Options: 

No effective treatment is known.

References
Article Title: 

The clinical, histochemical, and molecular spectrum of PEO1(Twinkle)-linked adPEO

Fratter C, Gorman GS, Stewart JD, Buddles M, Smith C, Evans J, Seller A, Poulton J, Roberts M, Hanna MG, Rahman S, Omer SE, Klopstock T, Schoser B, Kornblum C, Czermin B, Lecky B, Blakely EL, Craig K, Chinnery PF, Turnbull DM, Horvath R, Taylor RW. The clinical, histochemical, and molecular spectrum of PEO1(Twinkle)-linked adPEO. Neurology. 2010 May 18;74(20):1619-26.

PubMed ID: 
20479361

External Ophthalmoplegia, ANT1 and mtDNA Mutations

Clinical Characteristics
Ocular Features: 

Ptosis and progressive external ophthalmoplegia are the outstanding features of this form of external ophthalmoplegia.  These symptoms may appear in early adulthood.  A few patients have had thyroid disease as well.  Muscle biopsies from limb muscles show the characteristic ragged red appearance of myopathy in a minority of fibers.  Multiple deletions occur in the mitochondria of skeletal muscles.  EMG studies show myopathy while nerve conduction studies are normal.  Respiratory chain analysis often shows evidence of mitochondrial dysfunction.

Systemic Features: 

Adult patients with SLC25A4 (4q35.1) and mtDNA (ANT1) mutations have exercise intolerance and sometimes skeletal muscle weakness.  They are less likely to have symptoms of parkinsonism or peripheral neuropathy than those with mutations in POLG.  Hearing loss is minimal.

Genetics

This autosomal dominant disorder results from the combination of a mutation in the ANT1 (SLC25A4) gene (4q35) (encoding the adenine nucleotide translocator-1) and mitochondrial DNA deletions.  About 11% of autosomal dominant cases with progressive external ophthalmoplegia have mutations in this gene.  Most reported families have been from Italy.

External ophthalmoplegia may also result from mutations in POLG (most common), and in C10ORF2.

Pedigree: 
Autosomal dominant
Treatment
Treatment Options: 

No effective treatment is available.

References
Article Title: 

External Ophthalmoplegia, POLG and mtDNA Mutations

Clinical Characteristics
Ocular Features: 

Progressive external ophthalmoplegia of these types is often associated with widespread neurological and muscle manifestations.  The ophthalmoplegia is adult in onset and frequently combined with exercise intolerance.  Significant lens opacities may be seen in early childhood but may not cause vision problems until early adulthood. Progressive ptosis is often an early and disabling sign.

Systemic Features: 

Facial muscles can be weak, generally in older individuals.  Some patients complain of dysphagia.  Sensoirneural hearing loss, dysarthria, and dysphonia are often associated.  Neurological symptoms include ataxia, sensory neuropathy, tremors, depression and symptoms of parkinsonism but these are variable.   Some patients experience rhabdomyolysis following alcohol consumption.  Dilated cardiomyopathy can be a part of the autosomal recessive form of this disease.

A possible subcategory of this disease is associated with hypogonadism evidenced by delayed sexual maturation, primary amenorrhea, early menopause and testicular atrophy.  Other features as described above may be associated.  Muscle biopsy shows ragged-red fibers with multiple mitochondrial deletions.

Genetics

Progressive external ophthalmoplegia of the type described here is the result of mutations in the autosomal gene POLG combined with deletions in mitochondrial DNA.  POLG mutations account for 13-45% of patients with progressive external ophthalmoplegia who also have mitochondrial deletions.  The inheritance pattern in some families resembles the classical autosomal dominant pattern (PEOA1, 157640) whereas in others the pattern suggests autosomal recessive transmission (PEOB, 258450).  The autosomal defect is in the POLG gene at locus 15q25 which codes for the nuclear-encoded DNA polymerase-gamma gene.  The phenotype in the recessive disease tends to be more severe than in autosomal dominant cases. 

Other autosomal mutations with a less complex clinical picture associated with ophthalmoplegia are located in genes ANT1 (SLC25A4) (609283) at 4q35, and C10ORF2 (606075) at 10q24.

Pedigree: 
Autosomal dominant
Autosomal recessive
Treatment
Treatment Options: 

No effective treatment is available for the general disorder but consideration should be given to ptosis repair.

References
Article Title: 

Stickler Syndrome, Type II

Clinical Characteristics
Ocular Features: 

Virtually all (85%) patients have a nonprogresssive axial myopia.  The vitreous degeneration has a beaded pattern without the veils of type I, claimed by some to be important in the distinction of the two types.  Paravascular lattice retinopathy is seen in 38% of patients and 64% have cataracts, sometimes with wedge opacities similar to those in type I Stickler syndrome.  Nearly half (42%) of patients are reported to have retinal detachments.

Systemic Features: 

Hearing loss occurs early and many individuals (80%) eventually require hearing aids.    Midline clefting is present frequently with bifid uvula, a highly arched palate, or an actual cleft palate.  Joint laxity is common.

Genetics

There are reasons to classify type II Stickler syndrome as a unique disorder apart from type I (108300).  In addition to phenotypic evidence (vitreoretinal disease, amount of hearing loss, and degree of epiphyseal disease), mutation in two different genes are involved.  Type II results from a mutation in the COL11A1 (1p21) and type I (108300) in COL2A1.  Both types are inherited in autosomal dominant patterns.

Type IV (614234) with vitreoretinal changes, myopia, and a high risk of retinal detachment is inherited in an autsomal recessive pattern.

Pedigree: 
Autosomal dominant
Treatment
Treatment Options: 

Patients with type II Stickler disease need lifelong ophthalmologic monitoring because of the risk of retinal detachments and cataracts with treatment as indicated.
 

References
Article Title: 

Clinical features of type 2 Stickler syndrome

Poulson AV, Hooymans JM, Richards AJ, Bearcroft P, Murthy R, Baguley DM, Scott JD, Snead MP. Clinical features of type 2 Stickler syndrome. J Med Genet. 2004 Aug;41(8):e107.

PubMed ID: 
15286167

Kniest Dysplasia

Clinical Characteristics
Ocular Features: 

High myopia and vitreoretinal degeneration are characteristic ocular features in this disorder.   The myopia is in the range of -7.5 to -15.25 with most patients having about -11 diopters.  Acuity may be normal but inoperable retinal detachments can lead to blindness.  The vitreous demonstrates liquefaction and syneresis and often detaches posteriorly forming a retrolental curtain.  About half of affected eyes have perivascular lattice degeneration and the same proportion of patients at some point develop a retinal detachment.  Giant tears and retinal dialysis are commonly the cause.  The lens is often dislocated and cataracts are common.

Systemic Features: 

Short stature, cleft palate, stiff joints, and conductive hearing loss are characteristic extraocular features of Kniest dysplasia.  Some patients develop frank joint contractures and many are unable to make a tight fist due to inflexibility of the interphalangeal joints.  Lumber kyphoscoliosis is common.  Epiphyseal cartilage has a 'Swiss cheese appearance' with prominent lacunae.  The facies are round and the midface is underdeveloped with a flat nasal bridge.  Mild psychomotor retardation is sometimes seen.  

High levels of keratin sulfate are found in the urine.

Genetics

Mutations in the COL2A1 gene (12q13.11-q13.2) coding for type II collagen is responsible for this autosomal dominant disorder. This is one of a number of disorders known as type II collagenopathies (see Stickler syndrome I [609508]).  The clinical features arise from a defect in type II procollagen.

Pedigree: 
Autosomal dominant
Treatment
Treatment Options: 

There is no treatment for the dysplasia.  Displaced lenses can be removed but the myopia and degenerated vitreous require a cautious approach.  Rhegmatogenous detachments demand prompt attention.

References
Article Title: 

Ophthalmic and molecular genetic findings in Kniest dysplasia

Sergouniotis PI, Fincham GS, McNinch AM, Spickett C, Poulson AV, Richards AJ, Snead MP. Ophthalmic and molecular genetic findings in Kniest dysplasia. Eye (Lond). 2015 Jan 16. doi: 10.1038/eye.2014.334. [Epub ahead of print].

PubMed ID: 
25592122

The Kniest syndrome

Siggers CD, Rimoin DL, Dorst JP, Doty SB, Williams BR, Hollister DW, Silberberg R, Cranley RE, Kaufman RL, McKusick VA. The Kniest syndrome. Birth Defects Orig Artic Ser. 1974;10(9):193-208.

PubMed ID: 
4214536

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

Weill-Marchesani Syndrome 2

Clinical Characteristics
Ocular Features: 

Glaucoma may have an infantile onset and pupillary block glaucoma is a lifelong risk.  The lenses dislocate inferiorly but may migrate into the anterior chamber.  Spherophakia occurs in 74% of patients.  Extreme myopia in the range of -13 D may be present.  There is an increased risk of retinal detachment.

Systemic Features: 

One patient had mitral valve insufficiency.  Midface hypoplasia with a protruding lower lip was found in two patients.  The elbow and perhaps other large joints have limited mobility and the interphalangeal joints are thickened with difficulty in full extension of the fingers.  Patients are short in stature and the digits are often short and stubby.  The skin is tanned and thickened in places.  Cardiac anomalies are present in 13% of patients.

Genetics

This is an autosomal dominant disorder resulting from heterozygous mutations in FBN1 (15q21.1).  It is thus allelic to the Marfan syndrome (154700).  Weill-Marchesani syndrome 1 (277600) is a clinically similar syndrome but results from homozygous mutations in ADAMTS10. Homozygous mutations in ADAMTS17 cause the Weill-Marchesani-Like syndrome (613195).

Some individuals with isolated autosomal dominant ectopia lentis (129600) have mutations in FBN1.

Pedigree: 
Autosomal dominant
Treatment
Treatment Options: 

Patients should be monitored for the occurrence of glaucoma and treated appropriately.  Frequent refractive checks are recommended.  Lens extraction may be indicated when the visual axis is obstructed by a displaced lens or when lens-induced glaucoma occurs.

References
Article Title: 

Clinical homogeneity and genetic heterogeneity in Weill-Marchesani syndrome

Faivre L, Dollfus H, Lyonnet S, Alembik Y, M?(c)garban?(c) A, Samples J, Gorlin RJ, Alswaid A, Feingold J, Le Merrer M, Munnich A, Cormier-Daire V. Clinical homogeneity and genetic heterogeneity in Weill-Marchesani syndrome. Am J Med Genet A. 2003 Dec 1;123A(2):204-7. Review.

PubMed ID: 
14598350

Marfan Syndrome

Clinical Characteristics
Ocular Features: 

Marfan syndrome typically has skeletal, ocular and cardiovascular abnormalities.  The globe is elongated creating an axial myopia and increasing the risk of rhegmatogenous retinal detachments.  Ectopia lentis is, of course, the classical ocular feature and is often if not always congenital with some progression.  The lenses most frequently dislocate superiorly and temporally and dilating the pupils often reveals broken and retracted lens zonules.  Phacodenesis and iridodenesis are commonly present even in the absence of evident lens dislocations. Cataracts develop several decades earlier than in unaffected individuals. The cornea is generally several diopters flatter than normal and there is an increased risk of open angle glaucoma.  There is considerable clinical variation among patients.

Systemic Features: 

Patients with the Marfan phenotype are usually tall with disproportionately long limbs (dolichostenomelia) and digits (arachnodactyly).   Patients frequently have scoliosis or kyphoscoliosis.  The joints are lax and hyperflexible although contractures can also occur.  The sternum is often deformed, either as a pectus excavatum, or sometimes pectus carinatum.  The hard palate is high and narrow resulting in crowding of the teeth and maloccclusion.  The defect in fibrillin is responsible for the weakness in connective tissue that leads to frequent cardiac valve malfunction, especially insufficiency of the aortic valve resulting from aortic dilatation, tear, and rupture.  The latter is often life-threatening as aortic dissection can be fatal.  Mitral valve prolapse is seen as well.  Cardiovascular disease is primarily responsible for the shortened life expectancy in this disease, more pronounced among males.

Genetics

As many as 25% of cases are caused by new mutations, but familial cases usually follow an autosomal dominant pattern of inheritance.  Autosomal recessive inheritance is claimed for several individuals in a consanguineous Turkish family.  Mutations in the fibrillin-1 gene (FBN1) on chromosome 15 (15q21.1) are considered responsible for the typical phenotype.  The exact nature of the fibrillin defect is unknown but the result is a generalized weakness in connective tissue.

The same gene is mutant in the autosomal dominant form of the Weill-Marchesani syndrome (608328) which is allelic to the Marfan syndrome.

Mutations in FBN1 have also been found in cases with isolated autosomal dominant ectopia lentis (129600).

Pedigree: 
Autosomal dominant
Treatment
Treatment Options: 

Isometric exercises such as weight lifting should be avoided as should contact sports in which blunt trauma to the chest may occur because of the weakened aortic wall due to cystic changes that predispose the athlete to aortic dissection.  A dislocated and/or cataractous lens may need to be removed from the visual axis, and, of course, periodic retinal examinations for retinal holes and retinal detachments should be made.   Beta-adrenergic blockade reduces the risk of aortic dilatation and improves survival.

Pravastatin has been reported to reduce aortic dilation in marfan mice.

References
Article Title: 

Pravastatin reduces marfan aortic dilation

McLoughlin D, McGuinness J, Byrne J, Terzo E, Huuskonen V, McAllister H, Black A, Kearney S, Kay E, Hill AD, Dietz HC, Redmond JM. Pravastatin reduces marfan aortic dilation. Circulation. 2011 Sep 13;124(11 Suppl):S168-73.

PubMed ID: 
21911808

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