ectopia lentis

Anterior Segment Dysgenesis 6

Clinical Characteristics
Ocular Features: 

This is a congenital anterior segment dysplasia syndrome.  Iris hypoplasia with transillumination, corectopia, iridodenesis, and iridocorneal adhesions can be seen.  Increased intraocular pressure is a risk and ectopia lentis is often present.  Peters anomaly and defects in all layers of the cornea may be present.

No foveal hypoplasia is present.

Systemic Features: 

No systemic abnormalities have been reported.

Genetics

A single male patient of native American/French Canadian background has been reported with compound heterozygous mutations in the CYP1B1 gene (2p22.2).

See Anterior Chamber Dysgenesis 8 for another autosomal recessive disorder with somewhat similar clinical features.  Three families with 4 affected individuals have been reported with homozygous or compound heterozygous mutations in the CPAMD8 gene (19p13.11).

The genes FOXE3 and PAX6 are characterized as transcription factors and play important roles in ocular development.  However, while mutations in these are frequently found in patients with dysgenesis of the anterior chamber they often cause more widespread ocular and systemic anomalies (e.g., Gillespie syndrome [206700]).  Therefore in this database the anterior chamber constellations of anomalies associated with mutations in these genes are not considered to be simplex conditions.

See also related disorders iridogoniodysgenesis type 1 (601631) and type 2 (137600), and anterior segment mesenchymal dysgenesis (107250).

Pedigree: 
Autosomal recessive
Treatment
Treatment Options: 

Lifelong pressure monitoring is important.

References
Article Title: 

Phenotypic heterogeneity of CYP1B1: mutations in a patient with Peters' anomaly

Vincent A, Billingsley G, Priston M, Williams-Lyn D, Sutherland J, Glaser T, Oliver E, Walter MA, Heathcote G, Levin A, Heon E. Phenotypic heterogeneity of CYP1B1: mutations in a patient with Peters' anomaly. J Med Genet. 2001 May;38(5):324-6. PubMed PMID: 11403040; PubMed Central PMCID: PMC1734880.

PubMed ID: 
11403040

Anterior Segment Dysgenesis 8

Clinical Characteristics
Ocular Features: 

This is a congenital anterior segment dysplasia syndrome with considerable clinical heterogeneity.  Iris hypoplasia with transillumination, corectopia, iridodenesis, and iridocorneal adhesions are often seen.  Intraocular pressure may be elevated in older individuals.  Ectopia lentis is often present.  Lenticular opacities consisting primarily of posterior cortical opacification are common.  Visual acuity varies from 6/6 to 6/24.

No foveal hypoplasia is present but one of four reported patients was described with bilateral optic nerve dysplasia.     

Systemic Features: 

No systemic abnormalities have been reported.

Genetics

Three families with 4 affected individuals with similar clinical features have been reported with homozygous or compound heterozygous mutations in the CPAMD8 gene (19p13.11).

A single male patient of native American/French Canadian background with somewhat similar clinical features has been reported with compound heterozygous mutations in the CYP1B1 gene (2p22.2) but this is likely a unique condition (Anterior Segment Dysgenesis 6).

The genes FOXE3 and PAX6 are characterized as transcription factors and play important roles in ocular development.  However, while mutations in these are frequently found in patients with dysgenesis of the anterior chamber they often cause more widespread ocular and systemic anomalies (e.g., Gillespie syndrome [206700]).  Therefore in this database the anterior chamber constellations of anomalies associated with mutations in these genes are not considered to be simplex conditions. 

See also related disorders iridogoniodysgenesis type 1 (601631) and type 2 (137600), and anterior segment mesenchymal dysgenesis (107250).

Pedigree: 
Autosomal recessive
Treatment
Treatment Options: 

Several patients have had cataract surgery.  Monitoring intraocular pressure throughout life is necessary and prompt treatment for glaucoma is important.

References
Article Title: 

Marfan Lipodystrophy Syndrome

Clinical Characteristics
Ocular Features: 

The eyes are large resulting in high myopia and apparent proptosis.  The palpebral fissures usually slant downwards and ectopia lentis may be present.  

Systemic Features: 

This syndrome shares many features of Marfan syndrome (154700) such as tall stature, dislocated lenses, myopia, high arched palate, aortic root and valvular anomalies, arachnodactyly, high arched palate, lax and hyperextensible joints, and pectus excavatum.  In addition, MFLS patients have retrognathia, intrauterine growth retardation, scarce or absent subcutaneous fat, a progeroid facies, and sometimes macrocephaly.  Postnatal growth and psychomotor development have been reported to be normal albeit with slow weight gain.

Genetics

This condition is transmitted as an autosomal dominant as the result of heterozygous mutations in FBN1 (15q21.1).  The same gene is mutated in 6 other conditions in this database including Marfan Syndrome (154700) with which it shares some features.

Pedigree: 
Autosomal dominant
Treatment
Treatment Options: 

There is no treatment for the overall condition but individual features such as ectopia lentis can be surgically corrected.  Patients with high myopia require frequent evaluation for retinal tears and detachments.  Cardiac monitoring likewise is important to monitor for aortic valve prolapse and dilation of the aortic root.

References
Article Title: 

Knobloch Syndrome 3

Clinical Characteristics
Ocular Features: 

High myopia and marked nystagmus are cardinal ocular findings.  Night blindness leads to symptoms between 2 and 4 years of age.  Vision loss leads to complete blindness by age 15 to 18.  Visual acuity in young adults is often 20/400 to NLP.  Cataracts with subluxated lenses, glaucoma, and chorioretinal atrophy are often present.  Scattered pigment clumping, attenuation of the retinal vasculature, and prominent choroidal vessels can often be seen.  Marked optic atrophy is usually present.  Phthisis and band keratopathy may be seen in older individuals although no retinal detachments have been reported.  The vitreous is described as degenerated in several patients and a vitreal hemorrhage was seen in one patient.

Systemic Features: 

This variant was identified in a four-generation consanguineous Pakistani family in which detailed information was obtained in 5 members. A hairless, purplish-red patch is usually present in the occipital-parietal region during infancy but becomes smaller as children grow.  No encephalocele is present.  Hearing loss and heart defects have not been reported.  Intelligence is normal.

Genetics

This is an autosomal recessive condition resulting from a presumed homozygous mutation on chromosome 17 (17q11.2).

Other variants of Knobloch syndrome are Knobloch 1 (267750) caused by homozygous mutations in COL18A1 (21q22.3) and Knobloch 2 (608454) secondary to homozygous mutations in ADAMTS18 at 16q23.1.

Pedigree: 
Autosomal recessive
Treatment
Treatment Options: 

Cataracts and dislocated lenses may be removed.

References
Article Title: 

Knobloch Syndrome 2

Clinical Characteristics
Ocular Features: 

In an 18 month infant, ectopia lentis, cataract, and myopia with poor vision were noted.  This individual subsequently developed retinal degeneration and a serous retinal detachment.

Systemic Features: 

Only one patient has been reported.  While the clinical signs resemble Knobloch 1 syndrome, brain imaging does not reveal malformations in this syndrome.  The only systemic sign, in addition to an occipital encephalocele, is a minor delay in fine motor skills.

Genetics

This autosomal recessive disorder results from homozygous loss of function mutations in the ADAMTS18 gene (16q23.1).  The gene product has been found in the lens and retina in the murine eye.

Mutations in ADAMTS18 have also been found in the syndrome of Micorcornea, Myopia, Chorioretinal atrophy, and Telecanthus.  It may also be responsible for a retinal dystrophy.

Knobloch 2 syndrome was identified in a single female born to consanguineous parents.

This disorder is separate to Knobloch 1 syndrome (267750) based on the causative mutations.  A third type, KNO3, has been proposed since the Knobloch clinical features were found in a 4-generation consanguineous Pakistani family but the phenotype mapped to 17q11.2.

Pedigree: 
Autosomal recessive
Treatment
Treatment Options: 

The skull defect can be closed and the lenses can be removed if indicated.

References
Article Title: 

Knobloch Syndrome 1

Clinical Characteristics
Ocular Features: 

The ocular findings include high myopia, vitreoretinal degeneration, dislocated lenses, cataracts, and retinal detachment.  Some patients have early onset (2-4 years old) night blindness and progress to total blindness before 20 years of age.  Nystagmus, strabismus, small optic discs, glaucoma, and cataracts have been reported.  Poor vision and progressive loss of acuity are common.  The vitreous appears to be condensed into sheets and there may be distortion of the vitreoretinal interface with irregular white dots and lines.  Pigmentary changes are common in the retina which some have described as consistent with choroidal sclerosis and chorioretinal atrophy.  Atrophic changes are often seen in the macula.

Systemic Features: 

The degree of skull and brain defects is variable.  Some patients have only occipital scalp defects while others have occipital encephaloceles.  The scalp defect may contain heterotopic neuronal tissue suggesting neuronal migratory defects.  Brain imaging has revealed a variety of defects and some patients have cognitive deficits and personality changes.  Cerebellar atrophy with ataxia is found in some patients.

Genetics

This is an autosomal recessive disorder secondary to homozygous mutations in the COL18A1 gene (21q22.3).  Mutated COL18A1 leads to defects in type XVIII collagen which is a component of basement membranes throughout the body, especially in the eye.

In spite of some clinical similarities, this disorder is genetically distinct from Knobloch 2 syndrome (608454).  A third type, KNO3, has been proposed since the Knobloch clinical features were found in a 4-generation consanguineous Pakistani family but the phenotype mapped to 17q11.2.

Pedigree: 
Autosomal recessive
Treatment
Treatment Options: 

Treatment is largely supportive.  Attempts at repair of retinal detachments often fail and phthisis bulbi is not uncommon.

References
Article Title: 

Myopia, AR, with Cataracts and Vitreoretinal Degeneration

Clinical Characteristics
Ocular Features: 

Axial myopia and poor vision are noted during childhood.  Most individuals have refractive errors in the range of-5 to -18 diopters with a mean spherical equivalent of -11.3 diopters.  The axial length ranges from 25.1 and 30.5 mm.  Peripheral vitreoretinal degeneration and cataracts are usually present after the onset of myopia.  Lenticular opacities may necessitate cataract surgery in 11 of the 13 myopic patients in one kindred, usually by the second decade of life.  Lens instability or frank subluxation was noted in 8 patients.  At least five eyes suffered retinal detachments secondary to retinal dialyses and blindness of at least one eye occurred in 23% of patients.

Systemic Features: 

Deafness was reported in a single patient.

Genetics

This condition results from homozygous mutations in the gene LEPREL1 (3q28) encoding prolyl 3-hydroxylase.  It was identified in a large consanguineous Israeli Bedouin kindred containing seven affected males and 6 affected females.

Pedigree: 
Autosomal recessive
Treatment
Treatment Options: 

Cataract and retinal surgery may be indicated. However, the instability of the lens can lead to complications. The nature and location of retinal tears likewise make repairs difficult and blindness is a relatively frequent complication.

References
Article Title: 

Spherophakia, Isolated

Clinical Characteristics
Ocular Features: 

Small, spherical lenses are characteristic of this entity.  Lenticular myopia is usually present but no increased axial length.  Glaucoma has been reported in several individuals and speculated to be due to pupillary block.  No buphthalmos or angle anomalies were present.  The lens may sublux into the vitreous cavity.

Systemic Features: 

No skeletal, cardiovascular or metabolic disease is present.

Genetics

Isolated spherophakia is an autosomal recessive disorder resulting from homozygous mutations in LTBP2 (13q24.1-q32.12).  Parental consanguinity was present in reported families. 

Spherophakia is a clinically and genetically heterogeneous disorder and usually found in association with systemic findings.  It is commonly seen in the Weill-Marchesani syndrome 1 (277600), in Weill Marchesani syndrome 2 (608328), in the Weill-Marchesani-Like syndrome (613195), in a condition known as ‘megalocornea, ectopia lentis, and spherophakia’ (?), another one called 'spherophakia and hernia' (157150), sulfite oxidase deficiency (272300), primary congenital glaucoma D (613086) and in a syndrome known as ‘spherophakia and metaphyseal dysplasia’ (157151).

Pedigree: 
Autosomal recessive
Treatment
Treatment Options: 

The lenses may require extraction for secondary glaucoma and/or visual rehabilitation.

References
Article Title: 

Spherophakia with Inguinal Hernia

Clinical Characteristics
Ocular Features: 

Individuals with this condition have small spherical lenses that are usually displaced superiorly.  Myopia, both lenticular and axial, is often present and retinal detachments can occur.  Glaucoma was reported in one patient but this followed surgery for a retinal detachment.  Iridodenesis and nystagmus may be present.  The single report mentions strong zonules that created difficulties during intracapsular lens removal.  None of the spherical lenses were reported to migrate into the anterior chamber nor was lens-induced glaucoma present.

Systemic Features: 

Inguinal hernias are the only systemic manifestation of this disorder.  Four of 11 affected individuals in the family reported required surgery.  Physical examination and skeletal measurements were used to rule out the Marfan and Weill Marchesani syndromes.

Genetics

A single family with 11 affected individuals in 4 generations has been reported.  The four generation pedigree suggested autosomal dominant inheritance but nothing is known regarding the mutation or locus.

Spherophakia is a clinically and genetically heterogeneous disorder and usually found in association with systemic findings.  It is commonly seen in the Weill-Marchesani syndrome 1 (277600), in Weill Marchesani syndrome 2 (608328), in the Weill-Marchesani-Like syndrome (613195), in a condition known as ‘megalocornea, ectopia lentis, and spherophakia’ (?), and in a syndrome known as ‘spherophakia and metaphyseal dysplasia’ (157151).  Autosomal recessive isolated spherophakia (251750) has been found in several families.

Pedigree: 
Autosomal dominant
Treatment
Treatment Options: 

Lens extraction may be necessary for vision rehabilitation if it is partially displaced.

References
Article Title: 

Dominant microspherophakia

Johnson VP, Grayson M, Christian JC. Dominant microspherophakia. Arch Ophthalmol. 1971 May;85(5):534-7.

PubMed ID: 
5087595

Weill-Marchesani-Like Syndrome

Clinical Characteristics
Ocular Features: 

Several families have been reported in which the ocular features were similar to Weill-Marchesani syndromes WMS1 and WMS2 but lacked most of the skeletal features.  The ocular abnormalities included: myopia, ectopia lentis, spherophakia, and glaucoma.  Shallow anterior chambers and peripheral iris synechiae are often present. Axial length ranges from 21 to 23 mm.

Systemic Features: 

Short stature is a feature of this syndrome but brachydactyly and decreased joint mobility are not present.  Height is usually below the 25th percentile and often at the third or 5th percentile.

 

Genetics

This is an autosomal recessive disorder resulting from mutations in ADAMTS17 (15q26.3).  See also Weill-Marchesani Syndrome 1 (277600), and Weill-Marchesani Syndrome 2 (608328) for other conditions with clinical similarities but caused by different mutations.

Homozygous mutations in LTBP2 (14q24.3) have also been found in this disorder and in WMS1 (277600).

Pedigree: 
Autosomal recessive
Treatment
Treatment Options: 

Glaucoma requires the usual treatments.  The lens may need to be removed for visual rehabilitation and/or lens induced glaucoma.

References
Article Title: 

LTBP2 mutations cause Weill-Marchesani and Weill-Marchesani-like syndrome and affect disruptions in the extracellular matrix

Haji-Seyed-Javadi R, Jelodari-Mamaghani S, Paylakhi SH, Yazdani S, Nilforushan N, Fan JB, Klotzle B, Mahmoudi MJ, Ebrahimian MJ, Chelich N, Taghiabadi E, Kamyab K, Boileau C, Paisan-Ruiz C, Ronaghi M, Elahi E. LTBP2 mutations cause Weill-Marchesani and Weill-Marchesani-like syndrome and affect disruptions in the extracellular matrix. Hum Mutat. 2012 Apr 26. doi: 10.1002/humu.22105. [Epub ahead of print] PubMed PMID: 22539340.

PubMed ID: 
22539340

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