glaucoma

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

Weill-Marchesani Syndrome 1

Clinical Characteristics
Ocular Features: 

The Weill-Marchesani phenotype is a rare connective tissue disorder manifested by short stature, brachydactyly, spherophakia and stiff joints.   As many as 94% have spherophakia and 64% have dislocated lenses.  The central corneal thickness is increased.  The small, abnormally shaped lens can migrate anteriorly causing pupillary block glaucoma and sometimes dislocates into the anterior chamber.  This may occur spontaneously or following pharmacologic mydriasis which is sometimes done to relieve the pupillary block.

Systemic Features: 

Short stature in the range of 155 cm in height for men and 145 cm for women is common.  Brachydactyly and stiff joints prevent patients from making a tight fist.   A few patients (13%) have some mild mental deficit but most have normal intelligence.  Cardiac defects include patent ductus arteriosis, pulmonary stenosis, prolonged QT interval mitral valve stenosis, and mitral valve prolapse.  Some heterozygous carriers also are short in stature and may have joint stiffness.

Genetics

Homozygous mutations in the ADAMTS10 gene (19p13.3-p13.2) cause this disorder.  Homozygous mutations in LTBP2 (14q24.3) have also been found in WMS1 and in the Weill-Marchesani-Like syndrome (613195).

Weill-Marchesani syndrome 2 (608328) is a clinically similar syndrome but results from heterozygous mutations in FBN1. Homozygous mutations in ADAMTS17 cause the Weill-Marchesani-Like syndrome (613195) .  It is not always possible to distinguish between the AR and AD forms of the disease using clinical criteria alone.

 

Pedigree: 
Autosomal recessive
Treatment
Treatment Options: 

Dislocated lenses should be removed if they are interfering with vision or migrate into the anterior chamber.  A peripheral iridotomy should be considered in cases where pupillary block glaucoma occurs.  Long-term mydriasis is not recommended because of the risk of lens dislocation into the anterior chamber.  Chronic open angle glaucoma is a threat and life-long monitoring is recommended.  Measurements of the intraocular pressure should take the increased central corneal thickness into account.  Trabeculectomy should be considered when the pressure cannot be medically controlled.

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

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

Corneal Dystrophy, Congenital Endothelial 1

Clinical Characteristics
Ocular Features: 

(OMIM has combined this disorder with PPCD1 (122000) based on genetic and clinical evidence.)

Early onset limbus-to-limbus corneal clouding is the outstanding feature.  Some asymmetry is often present.  Vision is minimally impaired if at all in many children but slow progression occurs and adults often become visually impaired.  Nystagmus does not develop.  Photophobia and tearing are common.  The corneal appearance can lead to the erroneous diagnosis of congenital glaucoma.  However, some infants actually do have congenital glaucoma as well leading some to suggest this may be a disorder of anterior chamber dysgenesis.  The edematous cornea may be of 2-3 times normal thickness.  It may appear generally hazy and sometimes has a diffuse ground glass appearance.  

The posterior surface often appears mottled and has been described as having a peau d'orange appearance.  The endothelium is attenuated or even absent histologically and abnormal, disorganized collagen fibrils have been found in a thickened Descemet layer by electron microscopy.  The remaining endothelial cells are often vacuolated and heaped in double layers, with some containing melanin granules.  Some atrophy and edema of the epithelium with partial loss of Bowman's can be seen histologically.

Systemic Features: 

No systemic abnormalities are found in this disorder.

Genetics

This is an autosomal dominant disorder that maps to a locus on chromosome 20 (20p11.2-q11.2).   The molecular defect seems to involve the promotor of OVOL2 (20p11.23).  It is of interest that the posterior polymorphous corneal dystrophy 1 (PPCD1, 122000) mutation has been mapped to the same pericentric region, and it has been suggested that the two conditions may be allelic. These are now combined into a single entity in OMIM. 

This disorder should not be confused with congenital endothelial dystrophy type 2, CHED2 (217700) which is autosomal recessive, has an earlier presentation, and maps to a different region of chromosome 20.  Harboyan syndrome (217400) has similar corneal features but maps to a different location on chromosome 20 and is associated with sensorineural deafness.

The nosology of the corneal dystrophies is still evolving.  In the 2015 edition of the IC3D, this condition designated CHED1 is eliminated based on clinical and pathologic similarities to those in posterior polymorphous corneal dystrophy 1 (PPCD1, 122000).  However, while the loci for PPCD2 and CHED1 are located in the same pericentric region of chromosome 20, the purported mutations occur in different genes. 

 

Pedigree: 
Autosomal dominant
Treatment
Treatment Options: 

Penetrating keratoplasty carries a good visual prognosis, even when done late in life.

References
Article Title: 

IC3D classification of corneal dystrophies--edition 2

Weiss JS, Moller HU, Aldave AJ, Seitz B, Bredrup C, Kivela T, Munier FL, Rapuano CJ, Nischal KK, Kim EK, Sutphin J, Busin M, Labbe A, Kenyon KR, Kinoshita S, Lisch W. IC3D classification of corneal dystrophies--edition 2. Cornea. 2015 Feb;34(2):117-59. Erratum in: Cornea. 2015 Oct;34(10):e32.

PubMed ID: 
25564336

Corneal Dystrophy, Congenital Stromal

Clinical Characteristics
Ocular Features: 

This rare congenital form of stromal dystrophy is sometimes considered a disorder of collagen fibrils with abnormally small diameters.  These may appear disorganized in areas.  Corneal opacities are often evident at birth or during the neonatal period.  Numerous small spots of fluffy, flaky deposits are found throughout the stroma creating a diffuse cloudy appearance and these may become more numerous with age indicating some progression.  The epithelium, Descemet membrane and the endothelium are not affected and the stroma is of normal or slightly increased thickness.  In some areas abnormal fibrillar layers are seen.  Although corneal erosions and photophobia are usually not clinically significant, acuity may be as low as hand motions and penetrating keratoplasty may be indicated.  In one series this was necessary at an average age of 20 years.  In the same series of 11 patients, 4 had strabismus, 3 eyes developed open angle glaucoma and band keratopathy was present in one patient.  Nystagmus has not been reported.

Deposition of abnormal decorin contributes to the stromal opacities. 

Systemic Features: 

No systemic abnormalities have been reported.

Genetics

This is a rare autosomal dominant stromal dystrophy that results from a mutation in the DCN gene on chromosome 12 (12q21.3).  Several frameshift mutations have been reported    in the decorin (DCN) gene causing premature truncation of the protein product.

Pedigree: 
Autosomal dominant
Treatment
Treatment Options: 

Penetrating keratoplasty can be successful in restoring vision.  Grafts have been reported to remain clear for up to 36 years in more than half of the patients in one series but opacities recurred in others.

References
Article Title: 

Peters Anomaly

Clinical Characteristics
Ocular Features: 

Peters anomaly occurs as an isolated malformation but also as a feature of other syndromes.  It is often unilateral.  A wide variety of other ocular findings may occur with Peters anomaly as well. Here we limit our description to 'simple' Peters anomaly in which the findings are limited to the eye having the classic findings of adhesions of the iris to the posterior cornea and a central or paracentral corneal leukoma.  The lens may also be adherent to the cornea and is often opacified to some degree.  Descemet's membrane and portions of the posterior stroma are usually missing as well.  Glaucoma is frequently present.  Importantly, there is a wide range in the presentation of clinical features.

Systemic Features: 

Peters anomaly is a frequent feature of numerous syndromes, both ocular and systemic, among them the Peters-plus (261540) syndrome (sometimes called the Kivlin-Krause (261540) syndrome) and has been reported in a case with aniridia (106210).

Genetics

Isolated Peters anomaly usually occurs in an autosomal recessive pattern but autosomal dominant patterns have been reported as well.  The recessive disorder may be caused by a mutation in several genes, notably PAX6, PITX2,  CYP1B1, FOXC1, and FOXE3.  The latter gene is also mutated in anterior segment mesenchymal dysgenesis (107250) and congenital primary aphakia (610256).  The variety of clinical features are likely the result of a disruption in some common pathway or pathways.  Mutations in B3GALTL associated with the Peters-Plus syndrome have not been identified in isolated Peters anomaly.

This is a genetically and clinically heterogeneity condition as whole genome sequencing reveals numerous additional gene mutations in patients with both syndromic and isolated Peters anomaly.

PITX2 is also mutated in ring dermoid of the cornea (180550) and in Axenfeld-Rieger syndrome type 1 (180500).  PAX6 mutations also cause diseases of the cornea, fovea, optic nerve and iris.

Pedigree: 
Autosomal dominant
Autosomal recessive
Treatment
Treatment Options: 

Glaucoma is the most serious threat to vision on Peters anomaly but also the most difficult to treat.  Less than a third of patients achieve control of intraocular pressure even with the most vigorous combinations of therapy.  Corneal opacities can be treated with transplantation but the prognosis is often guarded when glaucoma is present.

From eye bank and other data, it has been estimated that 65% of penetrating keratoplasties in infants for visually significant congenital corneal opacities are performed in patients with Peters anomaly. 

References
Article Title: 

Whole exome sequence analysis of Peters anomaly

Weh E, Reis LM, Happ HC, Levin AV, Wheeler PG, David KL, Carney E, Angle B, Hauser N, Semina EV. Whole exome sequence analysis of Peters anomaly. Hum Genet. 2014 Sep 3. [Epub ahead of print].

PubMed ID: 
25182519

Ectopia Lentis et Pupillae

Clinical Characteristics
Ocular Features: 

This disorder is generally considered to consist of simple displacement of the pupil and dislocation of the lens (usually in opposite directions).  However, other abnormalities are often present such as persistent pupillary membrane (87%), iridohyaloid adhesions, increased corneal thickness, enlarged corneal diameters, and axial myopia.  The iris may transilluminate (67%) and the pupils dilate poorly.  Iridodenesis is common (85%).  The lens is often malformed and in some cases frankly microspherophakic.  The lens displacement can progress and cataracts seem to form at a relatively young age.  Visual acuity is highly variable, ranging from 20/20 to light perception depending upon the density of cataracts which often develop at a relatively young age. Prominent iris processes into the anterior chamber angle have been reported and glaucoma, both acute and chronic, is sometimes seen.  Retinal detachment is a risk.

Studies in families with ectopia lentis et papillae have revealed that as many as 50% of individuals with dislocated lenses do not have ectopic pupils.

Systemic Features: 

None reported

Genetics

This disorder is usually inherited in an autosomal recessive pattern.  Multiple affected sibs have been born to consanquineous matings.  However, other families in which detailed ophthalmological examinations were done have suggested dominant inheritance based upon the presence of more subtle ocular signs in relatives.  This is likely a more clinically heterogeneous disorder than has been appreciated.

In five Norwegian families a homozygous 20 bp deletion has been found in the gene ADAMTSL4 on chromosome 1 (c.767_786del20) (1q21.3) producing a frameshift and the introduction of a stop codon leading to truncation of the protein product.  Mutations in the same gene have also been found in the autosomal recessive form of isolated ectopia lentis (225100).

Pedigree: 
Autosomal recessive
Treatment
Treatment Options: 

Glaucoma, retinal detachments, and cataracts may require surgery.

References
Article Title: 

Aniridia 1

Clinical Characteristics
Ocular Features: 

Aniridia is the name of both a disorder and a group of disorders.  This because aniridia is both an isolated ocular disease and a feature of several malformation syndromes.  Absence of the iris was first reported in the early 19th century.  The hallmark of the disease is bilateral iris hypoplasia which may consist of minimal loss of iris tissue with simple radial clefts, colobomas, pseudopolycoria, and correctopia, to nearly complete absence.  Goniosocopy may be required to visualize tags of iris root when no iris is visible externally.  Glaucoma is frequently present (~67%) and often difficult to treat.  It is responsible for blindness in a significant number of patients.  About 15% of patients are diagnosed with glaucoma in each decade of life but this rises to 35% among individuals 40-49 years of age.  Hypoplasia and dysplasia of the fovea are likely responsible for the poor vision in many individuals.  Nystagmus is frequently present.  The ciliary body may also be hypoplastic. 

Visual acuity varies widely.  In many families it is less than 20/60 in all members and the majority have less than 20/200.  Photophobia can be incapacitating.  Posterior segment OCT changes suggest that outer retinal damage suggestive of a phototoxic retinopathy may also be a factor in the reduced acuity.  Cataracts (congenital in >75%), ectopia lentis (bilateral in >26%), optic nerve hypoplasia, variable degrees of corneal clouding with or without a vascularized pannus, and dysgenesis of the anterior chamber angle are frequently present. 

Increased corneal thickness (>600 microns) has been found in some series and should be considered when IOP measurements are made.  In early stages of the disease, focal opacities are present in the basal epithelium, associated with sub-basal nerves.  Dendritic cells can infiltrate the central epithelium and normal limbal palisade architecture is absent. 

Meibomian gland anomalies also contribute to the corneal disease.  The glands may be decreased in number and smaller in size contributing to deficiencies of the tear film and unstable surface wetting.

Systemic Features: 

In addition to 'pure' aniridia in which no systemic features are found, at least six disorders have been reported in which systemic anomalies do occur.  Three of these have associated renal anomalies, including Wilms tumor with other genitourinary anomalies and mental retardation, sometimes called WAGR (194072) syndrome, another (612469) with similar features plus obesity sometime called WAGRO (612469) syndrome reported in isolated patients, and yet another with partial aniridia (206750) and unilateral renal agenesis and psychomotor retardation reported in a single family.  Aniridia with dysplastic or absent patella (106220) has been reported in a single three generation family.  Cerebellar ataxia and mental retardation with motor deficits (Gillespie syndrome; 206700) have been found in other families with anirdia.  Another 3 generation family has been reported in which aniridia, microcornea and spontaneously resorbed cataracts occured (106230).

About one-third of patients with aniridia also have Wilms tumor and many have some cognitive deficits.

Genetics

The majority of cases have a mutation in the paired box gene (PAX6) complex, or at least include this locus when chromosomal aberrations such as deletions are present in the region (11p13).  This complex (containing at least 9 genes) is multifunctional and important to the tissue regulation of numerous developmental genes.   PAX6 mutations, encoding a highly conserved transcription regulator, generally cause hypoplasia of the iris and foveal hypoplasia but are also important in CNS development.  It has been suggested that PAX6 gene dysfunction may be the only gene defect associated with aniridia.  More than 300 specific mutations, most causing premature truncation of the polypeptide, have been identified.  

AN1 results from mutations in the PAX6 gene.  Two additional forms of aniridia have been reported in which functional alterations in genes that modulate the expression of PAX6 are responsible: AN2 (617141) with mutations in ELP4 and AN3 (617142) with mutations in TRIM44.  Both ELP4 and TRIM44 are regulators of the PAX6 transcription gene.

Associated abnormalities may be due to a second mutation in the WT1 gene in WAGR (194072) syndrome, a deletion syndrome involving both WT1 and PAX6 genes at 11p13.  The WAGRO syndrome (612469) is caused by a contiguous deletion in chromosome 11 (11p12-p13) involving three genes: WT1, PAX6, and BDNF.  All types are likely inherited as autosomal dominant disorders although nearly one-third of cases occur sporadically.

Mutations in PAX6 associated with aniridia can cause other anterior chamber malformations such as Peters anomaly (604229).

Gillespie syndrome (206700 ) is an allelic disorder with neurological abnormalities including cerebellar ataxia and mental retardation.

Pedigree: 
Autosomal dominant
Treatment
Treatment Options: 

Treatment is directed at the associated threats to vision such as glaucoma, corneal opacities, and cataracts.  Glaucoma is the most serious threat and is the most difficult to treat. The best results have been reported with glaucoma drainage devices.  All patients should have eye examinations at appropriate intervals throughout life, focused on glaucoma screening.  It is well to keep in mind that foveal maldevelopment often precludes significant improvement in acuity and heroic measures must be carefully evaluated.  Specifically, corneal transplants and glaucoma control measures frequently fail.

Low vision aids are often helpful.  Tinted lenses can minimize photophobia.  Occupational and vocational training should be considered for older individuals.  Surface wetting of the cornea should be periodically evaluated and appropriate topical lubrication used as needed. 

Young children with aniridia should have periodic examinations with renal imaging as recommended by a urologist.

In mice, postnatal topical ocular application of ataluren-based eyedrop formulations can reverse malformations caused by PAX6 mutations.

References
Article Title: 

Familial aniridia with preserved

Elsas FJ, Maumenee IH, Kenyon KR, Yoder F. Familial aniridia with preserved ocular function. Am J Ophthalmol. 1977 May;83(5):718-24.

PubMed ID: 
868970

Peters-Plus Syndrome

Clinical Characteristics
Ocular Features: 

Peters anomaly (306229) usually occurs as an isolated ocular malformation and is often unilateral.  However, in some patients with bilateral involvement it is part of a systemic syndrome or other congenital conditions such as chromosomal deletions and the fetal alcohol syndrome.  It is called Peters Plus syndrome in the condition described here because of the association of a specific combination of systemic features.

The ocular features are consistent with dysgenesis of the anterior chamber.  The clinical picture is highly variable but generally consists of iris adhesions to the cornea centrally (classical Peters anomaly), occasionally lenticular adhesions as well, and thinning of the central corneal stroma.  As a result, the cornea may become edematous, cataracts may develop, and glaucoma is common.

Systemic Features: 

Peters-plus syndrome consists of Peters anomaly plus various degrees of developmental delays and intellectual deficits, short digits and short stature, and cleft lip and palate.  The facies is said to be characteristic due to a prominent forehead, narrow palpebral fissures, and a cupid's bow-shaped upperlip. There may be preauricular pits present and the neck is often broad.  The ears may be prominent.  Congenital heart defects are present in a third of patients and a few have genitourinary anomalies.

Genetics

This is an autosomal recessive disorder of glycosylation caused by a mutation in the B3GALTL gene on chromosome 13 (13q12.3).  At least some patients have a splicing mutation in this gene leading to a skipping of exon 8.

Pedigree: 
Autosomal recessive
Treatment
Treatment Options: 

Treatment is directed at sight preservation by correcting the major ocular defects such as glaucoma and iridocorneal adhesions.  Corneal transplants and cataract removal are sometimes required.  Releasing the anterior synechiae can lead to significant clearing of the corneal edema.  Growth hormone replacement therapy may be beneficial.

References
Article Title: 

The Peters' plus syndrome: a review

Maillette de Buy Wenniger-Prick LJ, Hennekam RC. The Peters' plus syndrome: a review. Ann Genet. 2002 Apr-Jun;45(2):97-103. Review.

PubMed ID: 
12119218

Axenfeld-Rieger Syndrome, Type 1

Clinical Characteristics
Ocular Features: 

Axenfeld-Rieger syndrome consists of a heterogeneous group of disorders with overlapping features.  Common to all types are the presence of ocular, dental, facial, skeletal abnormalities and autosomal dominant inheritance.  Anterior chamber dysgenesis of some form is universally present and severe glaucoma occurs in 50% of patients.  This may have its onset in childhood with typical symptoms of congenital glaucoma such as photophobia, excessive tearing and corneal clouding.  Hypoplasia of the iris is common and when progressive may result in an ectopic pupil and/or pseudopolycoria.  Iris insertion and Schwalbe's line are often anteriorly displaced with iridocorneal adhesions, a pattern that leads to the inclusion of this disorder among those with iridogoniodysgenesis or anterior chamber dysgenesis.  Pupillary ectropion of the posterior pigmented layer of the iris may be seen.

There is considerable clinical overlap among conditions with iris dysgenesis.  Some patients with typical systemic features of Axenfeld-Rieger syndrome may even have typical anterior chamber features of Axenfeld-Rieger anomaly in one eye and severe iris hypoplasia resembling aniridia in the other.

Systemic Features: 

Dental anomalies and mid-facial hypoplasia secondary to underdeveloped maxillary sinuses are among the most common systemic features in type 1.  The nasal root often appears abnormally broad and the lower lip appears to protrude. The teeth are frequently small and conical in shape with wide spaces between them (diastema).  Some teeth may be missing.  The umbilicus may fail to involute normally and retains excessive, redundant skin that sometimes leads to the erroneous diagnosis of an umbilical hernia for which unnecessary surgery may be performed.  Hypospadius is frequently present while cardiac defects, sensorineural deafness, and anal stenosis are less common.

Genetics

There is clinical and genetic heterogeneity in this syndrome and precise classification of many families remains elusive without knowing the genotype.  Mutations in at least four genes are responsible and all are are responsible for phenotypes transmitted in autosomal dominant patterns.  Type 1 discussed here is caused by a mutation in the homeobox transcription factor gene, PITX2, located at 4q25-q26.  A type of iris hypoplasia (IH)/iridogoniodysgenesis (IGDS) (IRID2; 137600) disorder has been classified separately but is caused by a mutation in PITX2 as well and many cases have the same systemic features.  Mutations in the same gene have also been found in ring dermoid of the cornea (180550) and in some cases of Peters anomaly (604229).

RIEG2 (601499) is rare but a deletion of 13q14 has been reported in several cases.  Mapping in a large family with 11 affected individuals yielded a locus in the same region.  Clinical signs overlap types 1 and 3 with dental, craniofacial, and ocular features, but with hearing impairment and rare umbilical anomalies.

Mutations in the FOXC1 gene (6p25) may be responsible for RIEG3 (602482).  However, a family has been reported with a severe 'Axenfeld-Rieger phenotype' in which a digenic etiology may have been responsible: patients had mutations in both FOXC1 and PITX2. 

Heterozygous mutations in the PRDM5 gene (4q25-q26) have been identified in 4 members of a Pakistani family with typical features of the Axenfeld-Rieger syndrome. It is labeled type 4 Axenfeld-Rieger syndrome in this database. 

Pedigree: 
Autosomal dominant
Treatment
Treatment Options: 

The presence of glaucoma requires prompt and vigorous treatment but control is difficult with blindness too often the result.  Oral surgery may be beneficial for dental problems.  Low vision aids can be useful.

References
Article Title: 

Axenfeld-Rieger syndrome

Seifi M, Walter MA. Axenfeld-Rieger syndrome. Clin Genet. 2017 Oct 3. doi: 10.1111/cge.13148. [Epub ahead of print] Review.

PubMed ID: 
28972279

The Rieger syndrome

Jorgenson RJ, Levin LS, Cross HE, Yoder F, Kelly TE. The Rieger syndrome. Am J Med Genet. 1978;2(3):307-18.

PubMed ID: 
263445

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