ptosis

Optic Atrophy 1

Clinical Characteristics
Ocular Features: 

This form of bilateral optic atrophy may have its onset in early childhood with optic disc pallor, loss of acuity, loss of color vision, and centrocecal scotomas.  However, it is often not manifest until the second decade of life.  Moderate to severe temporal or diffuse pallor can be seen.  The optic disc has been described as normal in 29% of documented carriers and 20% have no visual field defect.  Pallor of the complete disc is found in only 10%.  Consequently, the phenotype is variable, with some individuals having minimal symptoms while others have severe vision loss.  The disease is progressive in some but not all families.  The median visual acutity is 20/70 but ranges from normal to hand motions.  

Histologic studies show atrophy of ganglion cells in the retina and loss of myelin sheaths in the optic nerve.   VEPs are absent or subnormal.  Optical coherence tomography reveals a significant reduction in retinal nerve fiber layer and ganglion cell layer thickness, most marked in the temporal quadrants.

Systemic Features: 

OPA1 is generally not associated with systemic disease.  However, some have sensorineural deafness, ataxia, ptosis, and ophthalmoplegia.  Families with both early and late onset have been reported.  Some (~20%) individuals have a myopathy as well.

Genetics

This is an autosomal dominant disorder resulting from mutations in a nuclear gene, OPA1 (3q28-q29).  The gene product is attached to the mitochondrial cristae of the inner membrane and metabolic studies have implicated the oxidative phosphorylation pathway which seems to be defective with reduced efficiency of ATP synthesis.  Penetrance approaches 90% but this is, of course, age dependent to some extent.

An allelic disorder (125250) is associated with sensorineural deafness, ataxia, and ophthalmoplegia but its uniqueness remains to be established since the same mutations in OPA1 have been found in both conditions.

Other autosomal dominant optic atrophy disorders include OPA5 (610708) and OPA4 (605293).

Pedigree: 
Autosomal dominant
Treatment
Treatment Options: 

No effective treatment is available.

References
Article Title: 

OPA1 in multiple mitochondrial DNA deletion disorders

Stewart JD, Hudson G, Yu-Wai-Man P, Blakeley EL, He L, Horvath R, Maddison P, Wright A, Griffiths PG, Turnbull DM, Taylor RW, Chinnery PF. OPA1 in multiple mitochondrial DNA deletion disorders. Neurology. 2008 Nov 25;71(22):1829-31.

PubMed ID: 
19029523

Saethre-Chotzen Syndrome

Clinical Characteristics
Ocular Features: 

The lids are often ptotic and asymmetrically so in keeping with the skull asymmetry.  Strabismus is common.  Optic atrophy, downward slanting lid fissures, epicanthal folds, and dacryostenosis have also been reported.

Systemic Features: 

The skull is acrocephalic and asymmetrical.  The frontal hairline is low.  The external ear and especially the crus of the ear are malformed and the latter is sometimes considered a valuable diagnostic sign.  There is frequently mild soft tissue syndactyly of the third, fourth and fifth toes, and the distal phalanges of the hallux may be bifid.  Syndactyly of the fingers is sometimes present as well.  Clefting of the soft and hard palates is commonly present and a few patients have had joint contractures.  Hearing loss of all types has been reported.  Mental development seems to be normal.  An increased risk of breast cancer has been found among Swedish patients.

SCS is considered to be one of the more common types of syndromic craniosynostosis.

Genetics

Saethre-Chotzen syndrome is caused by mutations in the TWIST1 (10q26) and possibly FGFR2 genes suggesting genetic heterogeneity.  There is also a great deal of clinical heterogeneity.  This syndrome is sometimes confused with Gorlin-Chaudhry-Moss syndrome (233500).  Pedigrees are consistent with autosomal dominant inheritance.

Pedigree: 
Autosomal dominant
Treatment
Treatment Options: 

There is no known treatment except for cranioplasty and repair of palate clefting.

References
Article Title: 

Cornelia de Lange Syndrome

Clinical Characteristics
Ocular Features: 

Many patients have few ocular findings beyond the usual synophyrs, a highly arched brow with hypertrichosis, and long eyelashes.  Synophrys is often prominent.  However, some also have significant ptosis, nystagmus, and high refractive errors.  Optic pallor and a poor macular reflex have also been reported.

Systemic Features: 

The facial features may be distinctive with low anterior hairline, anteverted nares, maxillary prognathism, long philtrum, crescent-shaped mouth and, of course, the bushy eyebrows and long lashes (in 98%).  Mental and growth retardation are common while many patients have features of the autism spectrum and tend to avoid social interactions.  The lips appear thin, the mouth is crescent-shaped, the head is often small, the teeth are widely spaced, and the ears are low-set.  The hands are often deformed with a proximally positioned thumb and metacarpophalangeal deformities.  It is stated that the middle phalanx of the index finger is always hypoplastic.  Other limb abnormalities of both upper (95%) and lower extremities are common.  Urinary tract abnormalities have been found in 41% of patients.  Middle ear effusions often lead to conductive hearing loss but 80% of patients have a sensorineural hearing deficit.

Genetics

This disorder is caused by mutations in genes encoding components of the cohesion complex.  Most cases occur sporadically but numerous familial cases suggest autosomal dominant inheritance. However, since at least three genes code for components of the cohesion complex including one located on the X-chromosome (610759), familial cases reported earlier without genotyping have created some confusion.  Hence, even autosomal recessive inheritance has been suggested in some families.  Genetic counseling should be family-specific based on the genotype and family pattern.

About 50% of cases result from mutations in the NIPBL gene (122470; 5p13.1) but less than 1% have an affected parent and the recurrence risk for sibs is similar.  The X-linked form of CDLS (300590; Xp11.22-p11.21) is caused by a mutation in the SMC1A gene, and a mild form (610759) results from mutations in the SMC3 gene (10q25).  Mutations in RAD21 (8q24) have been found in patients with milder disease and atypical presentations (614701).

A CDLS phenotype can also result from a specific duplication of a 3q 26-27 band.

Pedigree: 
Autosomal dominant
Autosomal recessive
Treatment
Treatment Options: 

No genetic treatment is available.

References
Article Title: 

BPES Syndrome

Clinical Characteristics
Ocular Features: 

This is primarily a dysplasia of the eyelids and adnexae.  The acronym is derived from the longer title sometimes used: blepharophimosis, ptosis, and epicanthus inversus syndrome.  The palpebral fissures are small and the curve of the epicanthal fold is mediolateral, but below the medial canthus.  The nasal bridge is flat or at least low, and the lids are ptotic.  Telecanthus may be present as well.  Refractive errors, strabismus, nystagmus, and amblyopia are often associated.  Entropion with trichiasis may require surgical attention.  Mutations in the FOX family of genes are associated with a wide variety of ocular anomalies including microcornea, trabecular dysgenesis, optic nerve hypoplasias and colobomas that are sporadically present in BPES syndrome.

Alacrima is a feature in many cases, caused by hypoplasia or aplasia of the major lacrimal gland.

Systemic Features: 

This condition is sometimes associated with ovarian failure although breast development is often normal.  The resultant infertility is an example of a sex-limited autosomal trait.  The syndrome can result from cytogenetic aberrations as well but individuals with these usually have other malformations such as contractures, mental defects, microcephaly, growth retardation, etc.

Some authors have considered individuals with the typical features of BPES who also have genitourinary malformations and cognitive deficits as examples of BPES plus syndrome.  A recent report, for example, describes two sibs, a male and a female, with some features of this syndrome plus posteriorly rotated ears, hypertelorism, telecanthus, micrognathia and severe psychomotor retardation.  The responsible mutation was not identified and its relationship to BPES remains unknown.  Another individual with typical ocular and systemic features of BPES in addition to cryptorchidism, developmental delay, and syndactyly, was found to have a mutation in the gene KAT6B in the absence of mutations in FOXL2. 

The phenotypic spectrum of this condition is extensive and it is likely that multiple mutations are collectively responsible for the clinical heterogeneity.

Genetics

This is an autosomal dominant condition with sex-limited characteristics in females (infertility, small uterus, atrophic ovaries).  The karyotype in females is normal.  It is one of the rare conditions with an apparent maternal age effect, at least in sporadic cases which are not uncommon. 

Mutations in the FOXL2 gene at 3q23 seem to be responsible for at least some familial cases. It codes for a gene active in the mesenchyme of the eyelids and in the ovarian follicle, at least in mice.  About 12% of patients do not have a FOXL2 mutation though. Numerous mutations have been found, some of which cause premature ovarian failure (sometimes labeled BPES type I) while others cause only lid maldevelopment (BPES type II).

A mutation in KAT6B (10q22.2) has been found in a single individual with features typical of BPES in whom no FOXL2 mutations were present.  It has been suggested that BPES patients without mutations in FOXL2 should be sequenced for mutations in KAT6B. 

Pedigree: 
Autosomal dominant
Treatment
Treatment Options: 

Lid surgery might be helpful in some patients with severe ptosis and/or trichiasis.

References
Article Title: 

Kearns-Sayre Syndrome

Clinical Characteristics
Ocular Features: 

Ptosis and progressive ophthalmoplegia usually have their onset before the second decade of life.  Pigmentary retinopathy is common with a variable clinical pattern of simple salt-and-pepper pigmentation or pigmentary clumping resembling retinitis pigmentosa.

Systemic Features: 

Atrioventricular conduction defects including complete heart block, cardiomyopathy, short stature, elevated CSF protein, and ataxia are among the most frequent extraocular features seen.  Pharyngeal, facial, and skeletal muscle weakness seem to be common features.  Growth retardation, delayed sexual maturation, and mental deterioration occur in some patients. Older patients have a sensorineural hearing deficit as well.

EEG abnormalities are often present.  CT scans reveals a diffuse leukoencephalopathy as well as a variety of CNS abnormalities in the cerebellum and brain stem.  Muscle biopsies reveal 'ragged red' fibers.

This is a progressive disorder and many patients die in the third or fourth decades of life.

Genetics

Unlike many syndromes of external ophthalmoplegia with deletions in mitochondria, no nuclear DNA mutations have been associated with this disorder.  However, it is a clinically and genetically heterogeneous condition.  Exclusively maternal transmission consistent with mitochondrial disease has been observed in some familial cases.  Other familial cases suggest autosomal inheritance and in some the transmission pattern is consistent with autosomal recessive inheritance.  Many if not most cases occur sporadically.

Mitochondrial DNA defects in muscle and brain vary in size and location and even the proportion of normal to abnormal mitochondria among cells varies. This may account for some of the clinical heterogeneity.

Treatment
Treatment Options: 

Coenzyme Q(10) may decrease fatigue with improvement in eye muscle movement and a lessening in the degree of heart block.  Pacemakers may be necessary in some patients.  Exercise is recommended for patients with significant skeletal myopathy.

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: 

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