macular pigmentation

Spastic Paraplegia 11

Clinical Characteristics
Ocular Features: 

Gaze evoked nystagmus and pigmentation in the macula are components of this syndrome and adults have some degree of retinal degeneration with poor vision eventually.  Optic atrophy and ptosis have been reported but rarely.   

Systemic Features: 

his progressive condition nay have its onset in childhood or early adolescence although rarely it first appears in adulthood.  Obesity is a component in older individuals.  Loss of ambulation usually occurs within 10 years of the onset of gait difficulties.  Hyperreflexia and spasticity develop early while ataxia, urinary sphincter disturbances, extensor plantar responses, and dysarthria appear later.  Amyotrophy is frequently seen in the thenar and hypothenar muscles.  Children have learning difficulties while cognitive decline and frank mental retardation occur somewhat later.  

Peripheral nerve biopsy may reveal hypomyelination and loss of unmyelinated nerve fibers.  MRI imaging in some individuals shows a thin or absent corpus callosum and cortical atrophy. 

Genetics

Homozygous mutations in the gene SPG11 (15q21.1) encoding spatacsin are responsible for this disorder. 

See spastic paraplegia 15 (Kjellin syndrome) (270700) and spastic paraplegia 7 (607259) for other disorders with retinal degeneration, optic atrophy, and nystagmus.

Pedigree: 
Autosomal recessive
Treatment
Treatment Options: 

None known.

References
Article Title: 

Mutations in SPG11, encoding spatacsin, are a major cause of spastic paraplegia with thin corpus callosum

Stevanin G, Santorelli FM, Azzedine H, Coutinho P, Chomilier J, Denora PS, Martin E, Ouvrard-Hernandez AM, Tessa A, Bouslam N, Lossos A, Charles P, Loureiro JL, Elleuch N, Confavreux C, Cruz VT, Ruberg M, Leguern E, Grid D, Tazir M, Fontaine B, Filla A, Bertini E, Durr A, Brice A. Mutations in SPG11, encoding spatacsin, are a major cause of spastic paraplegia with thin corpus callosum. Nat Genet. 2007 Mar;39(3):366-72.

PubMed ID: 
17322883

Macular Dystrophy, Patterned 2

Clinical Characteristics
Ocular Features: 

Abnormal pigmentation of yellow, white, or black color accumulates in the central area of the macula.  The deposition of pigment appears in the retinal pigment epithelium (RPE) level in a pattern more or less resembling the wings of a butterfly.  The peripheral retina has diffuse pigment mottling.  Drusen-like structures may be seen at the peripheral borders of the macular pigmentation.  Visual fields are normal usually but there may be some decrease in central sensitivity.

However, this is a generalized retinal disorder as revealed by the abnormal mass response (decreased light/dark ratio) of the electrooculogram (EOG).   Patients may not have visual symptoms until their late 20s or early 30s even though the pigmentation may be evident in the second decade.  Color vision, dark adaptation and the ERG are normal.  Younger patients may have normal vision.

Systemic Features: 

No systemic associations have been reported.

Genetics

This condition results from heterozygous mutations in the CTNNA1 gene (5q31).  For a similar disorder see Macular Dystrophy, Patterned 1 (169150).

As many as 25% of patients with myotonic dystrophy 1 (160900) and myotonic dystrophy 2 (602668) have a patterned pigmentary maculopathy.

Pedigree: 
Autosomal dominant
Treatment
Treatment Options: 

There is no known treatment.

References
Article Title: 

Mutations in CTNNA1 cause butterfly-shaped pigment dystrophy and perturbed retinal pigment epithelium integrity

Saksens NT, Krebs MP, Schoenmaker-Koller FE, Hicks W, Yu M, Shi L, Rowe L, Collin GB, Charette JR, Letteboer SJ, Neveling K, van Moorsel TW, Abu-Ltaif S, DeBaere E, Walraedt S, Banfi S, Simonelli F, Cremers FP, Boon CJ, Roepman R, Leroy BP, Peachey NS, Hoyng CB, Nishina PM, den Hollander AI. Mutations in CTNNA1 cause butterfly-shaped pigment dystrophy and perturbed retinal pigment epithelium integrity. Nat Genet. 2016 Feb;48(2):144-51.

PubMed ID: 
26691986
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