autosomal recessive

Neuraminidase Deficiency

Clinical Characteristics

Ocular Features

A cherry red spot is may be seen in late childhood or early adolescence.  It occurs in nearly 100% of patients with type I while only 75% of type II patients have this feature possibly because their early death from the more severe systemic disease prevents full ascertainment.  Visual acuity is reduced, sometimes severely.  Some but not all individuals have corneal and lens opacities.  A subtle corneal haze has also been seen.  Nystagmus has been reported. 

Systemic Features

This is a neurodegenerative disorder with progressive deterioration of muscle and central nervous system functions.  Myoclonus, mental deterioration, hepatosplenomegaly, muscle weakness and atrophy are common.  The defect in neuraminidase activity leads to abnormal amounts of sialyl-oligosaccharides in the urine.  Spinal deformities such as kyphosis are common.  Deep tendon reflexes are exaggerated.  Ataxia and hearing loss may be present.  Coarse facies, a barrel chest, and short stature are characteristic.  Hepatic cells contain numerous vacuoles and numerous inclusions.

Sialidosis types I and II are both caused by mutations in the neuroaminidase gene.  Type I is associated with milder disease than type II which has an earlier age of onset and may present in infancy or even begin in utero.  Early death within two years of age is common in the congenital or infantile forms.  There is, however, significant variability in age of onset and the course of disease among types. 

Genetics

The sialidoses are autosomal recessive lysosomal storage disorders resulting from mutations in the NEU1 gene (6p21.3) which lead to an intracellular accumulation of glycoproteins containing sialic acid residues.  Both types I and II are caused by mutations in the same gene. 

Treatment Options

Treatment is focused on symptom management. 

References

Heroman JW, Rychwalski P, Barr CC. Cherry red spot in sialidosis (mucolipidosis type I). Arch Ophthalmol. 2008 Feb;126(2):270-1.

PubMed ID: 
18268224

Goldberg MF. Macular cherry-red spot and corneal haze in sialidosis (mucolipidosis type 1). Arch Ophthalmol. 2008 Dec;126(12):1778; author reply 1778.

PubMed ID: 
19064869

Federico A, Cecio A, Battini GA, Michalski JC, Strecker G, Guazzi GC. Macular cherry-red spot and myoclonus syndrome. Juvenile form of sialidosis. J Neurol Sci. 1980 Nov;48(2):157-69.

PubMed ID: 
7431038

Sandhoff Disease

Clinical Characteristics

Ocular Features

Retinal ganglion cells become dysfunctional as a result of the toxic accumulation of intra-lysosomal GM2 ganglioside molecules causing early visual symptoms.  These cells in high density around the fovea centralis create a grayish-white appearance.  Since ganglion cells are absent in the foveolar region, this area retains the normal reddish appearance, producing the cherry-red spot.  Axonal decay and loss of the ganglion cells leads to optic atrophy and blindness. 

Systemic Features

Sandhoff disease may be clinically indistinguishable from Tay-Sachs disease even though the same enzyme is defective (albeit in separate subunits A and B that together comprise the functional enzymes).  The presence of hepatosplenomegaly in Sandoff disease may be distinguishing. The infantile form of this lysosomal storage disease seems to be the most severe.  Infants appear to be normal until about 3-6 months of age when neurological development slows and muscles become weak.  Seizures, loss of interest, and progressive paralysis begin after this together with loss of vision and hearing.  An exaggerated startle response is considered an early and helpful sign in the diagnosis.  Among infants with early onset disease, death usually occurs by 3 or 4 years of age.   

Ataxia with spinocerebellar degeneration, motor neuron disease, dementia, and progressive dystonia are more common in individuals with later onset of neurodegeneration.  The juvenile and adult-onset forms of the disease also progress more slowly.  

Genetics

Sandhoff disease results from mutations in the beta subunit of the hexosaminidase A and B enzymes.  It is an autosomal recessive disorder caused by mutations in HEXB (5q13). 

Tay-Sachs disease (272800) can be clinically indistinguishable from Sandoff disease and they are allelic disorders.  However, the mutation in Tay-Sachs (272800) is in HEXA resulting in dysfunction of the alpha subunit of hexosaminidase A enzyme. 

Treatment Options

No specific treatment is available beyond general support with proper nutrition and maintainence of airways.  Anticonvulsants may be helpful in some stages.  Gene therapy in fibroblast cultures has achieved some restoration of  hexosaminidase A activity in Tay-Sachs disease and may have potential in Sandhoff disease as well. 

References

Myerowitz R, Lawson D, Mizukami H, Mi Y, Tifft CJ, Proia RL. Molecular pathophysiology in Tay-Sachs and Sandhoff diseases as revealed by gene expression profiling. Hum Mol Genet. 2002 May 15;11(11):1343-50.

PubMed ID: 
12019216

Neufeld EF. Natural history and inherited disorders of a lysosomal enzyme, beta-hexosaminidase. J Biol Chem. 1989 Jul 5;264(19):10927-30. Review.

PubMed ID: 
2525553

Gilbert F, Kucherlapati R, Creagan RP, Murnane MJ, Darlington GJ, Ruddle FH. Tay-Sachs' and Sandhoff's diseases: the assignment of genes for hexosaminidase A and B to individual human chromosomes. Proc Natl Acad Sci U S A. 1975 Jan;72(1):263-7.

PubMed ID: 
1054503

Donnai-Barrow Syndrome

Clinical Characteristics

Ocular Features

A number of ocular features have been described in this disorder, including telecanthus, hypertelorism, and iris hypoplasia.  Patients may have marked iris transillumination.  Myopia is commonly present and retinal detachments are a risk.  Several patients had iris colobomas.  Cataracts, small optic nerves, and macular hypoplasia have been reported as well.  The lid fissures usually slant downward. 

Systemic Features

The facial dysmorphology, in addition to the periocular malformations, includes a prominent brow or frontal bossing, posterior rotation of the ears, a flat nasal bridge and a short nose.  Sensorineural hearing loss is universal and at least some patients have complete or partial agenesis of the corpus callosum, and an enlarged anterior fontanel.  Diaphragmatic and umbilical hernias often occur together.  Low-molecular-weight proteinuria in the absence of aminoaciduria is a frequent feature.  Developmental delays are often seen but occasional patients have normal intellect.  Rare patients have seizures. 

Genetics

This is a rare autosomal recessive disorder caused by homozygous mutations in the LRP2 (low-density lipoprotein receptor-related protein 2 or megalin) gene located at 2q24-q31.  Some patients have an ocular phenotype resembling the Stickler syndrome.

Treatment Options

Treatment is focused on specific manifestations such as cataract and retinal detachment surgery. Patients need to be monitored throughout life for retinal disease.  Omphaloceles and diaphragmatic hernias need to be repaired.  Hearing aids may be beneficial. 

References

Schrauwen I, Sommen M, Claes C, Pinner J, Flaherty M, Collins F, Van Camp G. Broadening the phenotype of LRP2 mutations: a new mutation in LRP2 causes a predominantly ocular phenotype suggestive of Stickler syndrome. Clin Genet. 2013 Aug 29. [Epub ahead of print] PubMed PMID: 23992033.

PubMed ID: 
23992033

Pober BR, Longoni M, Noonan KM. A review of Donnai-Barrow and facio-oculo-acoustico-renal (DB/FOAR) syndrome: clinical features and differential diagnosis. Birth Defects Res A Clin Mol Teratol. 2009 Jan;85(1):76-81. Review.

PubMed ID: 
19089858

Patel N, Hejkal T, Katz A, Margalit E. Ocular manifestations of Donnai-Barrow syndrome. J Child Neurol. 2007 Apr;22(4):462-4.

PubMed ID: 
17624530

Chassaing N, Lacombe D, Carles D, Calvas P, Saura R, Bieth E. Donnai-Barrow syndrome: four additional patients. Am J Med Genet A. 2003 Sep 1;121A(3):258-62. Review.

PubMed ID: 
12923867

Schowalter DB, Pagon RA, Kalina RE, McDonald R. Facio-oculo-acoustico-renal (FOAR) syndrome: case report and review. Am J Med Genet. 1997 Mar 3;69(1):45-9; discussion 44. Review.

PubMed ID: 
9066882

Neuronal Ceroid Lipofuscinoses

Clinical Characteristics

Ocular Features

At least 10 genotypically distinct forms of neuronal ceroid lipofuscinosis have been described.  The ocular features are highly similar in all forms with blindness the end result in all types (although not all cases with an adult onset suffer vision loss).  The onset of visual signs and symptoms is highly variable.  Optic atrophy is the most common finding which may occur as early as two years of age in the infantile form.  Night blindness is a symptom in those with a later onset but panretinal degeneration with unrecordable ERGs eventually occurs.  Pigmentary changes throughout the retina are often seen and sometimes occur in a bull’s-eye pattern.  Retinal blood vessels may be attenuated and lens opacities of various types are common. 

Systemic Features

The neuronal ceroid lipofuscinosis are a group of inherited neurodegenerative lysosomal-storage disorders characterized by the intracellular accumulation of autofluorescent lipopigment causing damage predominantly in the central nervous system.  The result is a progressive encephalopathy with cognitive and motor decline, eventual blindness, and seizures with early death.  While early descriptions distinguished several types based primarily on age of onset, genotyping has now identified responsible mutations in at least 10 genes and time of onset is no longer considered a reliable indicator of the NCL type. 

Genetics

The NCLs are usually inherited in autosomal recessive patterns with the exception of some adult onset cases in which an autosomal dominant pattern is sometimes seen.

The various forms of NCL are often divided according to ages of onset but overlap is common.  Thus the congenital form (CLN10; 610127), caused by a mutation in the CTSD gene at 11p15.5, can have an onset of symptoms at or around birth but also is responsible for an adult form (Vida infra).  The CLN1 infantile form (256730), caused by a mutation in the PPT1 gene at 1p32, has an onset between 6 and 24 months  There are several mutations causing late infantile disease (CLN2, 204500) involving the TPP1 gene (11p15.5) leading to symptoms between 2-4 years, the CLN5 gene (256731) at 13q21.1-q32 with onset between 4 and 7 years, the CLN6 gene (601780) at 15q21-q23 showing symptoms between 18 months and 8 years, and the CLN8 gene (610003) at 8p23 with symptoms beginning between 3 and 7 years.  Another early juvenile form (CLN7; 610951) is caused by mutations in MFSD8 (4q228.1-q28.2).

A juvenile form (sometimes called Batten disease or Spielmeyer-Vogt with onset between 4 and 10 years results from mutations in CLN3 (204200) as well as in TPP1, PPT1, and CLN9 (609055).  An adult form known as ANCL or Kuf’s disease results from mutations in CTSD, PPT, CLN3, CLN5, and CLN4 (204300) and has its onset generally between the ages of 15 and 50 years. 

Homozygous mutations in the ATP13A2 gene (1p36.13), known to cause Kufor-Rakeb type parkinsonism (606693), have also been found in NCL.

Treatment Options

Treatment is primarily symptomatic for sleep disorders, seizures, psychoses, malnutrition, dystonia and spasticity.  However, there is recent progress in the application of enzyme-replacement therapies in the soluble lysosomal forms of CNL.  Gene therapies and the use of stem cells also hold promise. 

References

Bras J, Verloes A, Schneider SA, Mole SE, Guerreiro RJ. Mutation of the Parkinsonism Gene ATP13A2 Causes Neuronal Ceroid-Lipofuscinosis. Hum Mol Genet. 2012 Mar 2. [Epub ahead of print].

PubMed ID: 
22388936

Wong AM, Rahim AA, Waddington SN, Cooper JD. Current therapies for the soluble lysosomal forms of neuronal ceroid lipofuscinosis. Biochem Soc Trans. 2010 Dec;38(6):1484-8.

PubMed ID: 
21118112

Goebel HH. The neuronal ceroid-lipofuscinoses. J Child Neurol. 1995 Nov;10(6):424-37.

PubMed ID: 
8576551

Hyperoxaluria, Primary, Type I

Clinical Characteristics

Ocular Features

About 30% of patients with type I develop retinopathy and about half of those have a diffuse optic atrophy.  Oxalate crystal deposition can cause a ‘fleck retina’ picture sometimes described as a crystalline retinopathy.  Retinal toxicity leads to early and progressive vision loss.  The RPE may respond with hyperpigmentation in the form of 'ringlets' in the posterior pole.  Retinal fibrosis has been described.  Some patients develop choroidal neovascularization.

Evaluation using EDI-OCT shows progressive deposition of oxalate crystals throughout the retina, pigment epiithelium, and choroid.

Systemic Features

The onset of this disease can occur any time from infancy to 25 years of age.  Failure to thrive can be a presenting sign in infants.  Most patients have glycolic aciduria and hyperoxaluria as the result of failure to transaminate glyoxylate to form glycine.  The result is deposition of insoluble oxalate crystals in various body tissues with nephrolithiasis and nephrocalcinosis often early signs.  Neurologic, cardiac, vascular, and kidney disease is often the result although oxalate crystals can be found throughout the body.  Arteriole occlusive disease may lead to gangrene, Raynaud phenomena, acrocyanosis and intermittent claudication.  Renal failure is common. 

Genetics

Hyperoxaluria type I is an autosomal recessive disorder resulting from a mutation in the alanine-glyoxylate aminotransferase gene (AGXT) located at 2q36-q37.  Failure of this liver peroxisomal enzyme to transaminate glyoxylate results in oxidation of this molecule to form oxalate.

Hyperoxaluria type II (260000) is caused by mutations in the GRHPR gene (9cen) and type III (613616) by mutations in DHDPSL (HOGA1) (10q24.2).  Urolithiasis is the only clinical feature in these types. 

Treatment Options

Some patients benefit from oral pyridoxine (B6) treatment in type I hyperoxaluria.  Renal transplantation by itself is only temporarily helpful since the enzymatic defect remains and the donor tissue becomes damaged as well.  Combined renal-liver transplantation should be considered instead because it corrects the primary metabolic error and can even reverse the accumulation of oxalate crystals. 

References

Cochat P, Rumsby G. Primary hyperoxaluria. N Engl J Med. 2013 Aug 15;369(7):649-58. Review.

PubMed ID: 
23944302

Roth BM, Yuan A, Ehlers JP. Retinal and Choroidal Findings in Oxalate Retinopathy Using EDI-OCT. Ophthalmic Surg Lasers Imaging. 2012 Nov 1;43(6):S142-4. doi: 10.3928/15428877-20121001-05.

PubMed ID: 
23357321

Beck BB, Hoyer-Kuhn H, Göbel H, Habbig S, Hoppe B. Hyperoxaluria and systemic oxalosis: an update on current therapy and future directions. Expert Opin Investig Drugs. 2012 Nov 21. [Epub ahead of print].

PubMed ID: 
23167815

Theodossiadis PG, Friberg TR, Panagiotidis DN, Gogas PS, Pantelia EM, Moschos MN. Choroidal neovascularization in primary hyperoxaluria. Am J Ophthalmol. 2002 Jul;134(1):134-7.

PubMed ID: 
12095827

Cochat P, Koch Nogueira PC, Mahmoud MA, Jamieson NV, Scheinman JI, Rolland MO. Primary hyperoxaluria in infants: medical, ethical, and economic issues. J Pediatr. 1999 Dec;135(6):746-50.

PubMed ID: 
10586179

Small KW, Letson R, Scheinman J. Ocular findings in primary hyperoxaluria. Arch Ophthalmol. 1990 Jan;108(1):89-93.

PubMed ID: 
2297338

Niemann-Pick Disease, Type C2

Clinical Characteristics

Ocular Features

The primary ocular feature of type C2 Niemann-Pick disease is supranuclear gaze palsy.  A cherry red spot is rarely seen. 

Systemic Features

Neurodegeneration is the outstanding clinical manifestation and often the cause of death.  The onset usually occurs in infancy and the course is rapid with death often in the first year of life.  The clinical disease is similar to that of the more common type C1 (257220) although there is considerable clinical heterogeneity in all types of NPC.  Pulmonary involvement can be a prominent feature of C2 disease.  Other neurologic symptoms include ataxia, facial dyskinesis, bradykinesia, expressive aphasia, dysarthria and cognitive decline.  Visceromegaly seems to be less common than in type C1 (257220).  Cholesterol esterification is impaired with accumulation in intracellular organelles. 

Genetics

Like other types of NPC disease, this disorder follows an autosomal recessive pattern of inheritance.  It results from mutations in the NPC2 gene (14q24.3).  These mutations are far less common than those in the NPC1 (257220)gene.  

Treatment Options

Treatment is available for symptoms such as seizures and dystonia.  Good pulmonary hygiene is important and precautions should be taken to prevent aspiration. 

References

Verot L, Chikh K, Freydière E, Honoré R, Vanier MT, Millat G. Niemann-Pick C disease: functional characterization of three NPC2 mutations and clinical and molecular update on patients with NPC2. Clin Genet. 2007 Apr;71(4):320-30.

PubMed ID: 
17470133

Verot L, Chikh K, Freydière E, Honoré R, Vanier MT, Millat G. Niemann-Pick C disease: functional characterization of three NPC2 mutations and clinical and molecular update on patients with NPC2. Clin Genet. 2007 Apr;71(4):320-30.

PubMed ID: 
17470133

Walker-Warburg Syndrome

Clinical Characteristics

Ocular Features

The eyes are usually small and contain either retinal dysplasia or a congenital retinal detachment.  Colobomas, PHPV, cataracts, glaucoma, buphthalmos, anterior chamber dysgenesis, optic atrophy, and optic nerve hypoplasia have also been reported. 

Systemic Features

Hydrocephalus and congenital muscular dystrophy are the most important systemic features of these syndromes.  A Dandy-Walker malformation is often present.  Type II lissencephaly, cerebellar malformations and severe mental retardation are other features.  More variable signs include macro- or microcephaly, ventricular dilatation, cleft lip and/or palate, and congenital contractures.  WWS has a severe phenotype and death often occurs in the first year of life.  Brain histology shows severely disorganized cytoarchitecture and suggests a neuronal migration disorder. Microtia has been reported in several patients.

Most developmental milestones are delayed or never achieved and death may occur in early childhood. 

Genetics

The MDDGs (muscular dystrophy dystroglycanopathies) comprise a genetically and clinically heterogeneous group of disorders (sometimes called muscle-eye-brain disease) of which the A types are more severe than the B types.  The mutant genes responsible are involved in glycosylation of DAG1 (alpha-dystroglycan). 

Types A1 (MDDGA1; 236670), B1 (MDDGB1; 613155) and C1 (MDDGC1; 609308) result from mutations in a gene known as POMT1 (9p34.1).  The muscular dystrophy in type C1 is of the limb-girdle type LGMD2K.

A2 (MDDGA2; 613150) is caused by mutations in POMT2 (14q24.3).  Mutations in POMT2 may also cause the less severe muscle-eye-brain disease (MEB) type B2 (MDDGB2; 613156), and a similar disease (C2) in which the muscle dystrophy is of the limb-girdle type LGMD2N and eye findings may be absent (MDDGC2; 613158).

Mutations in POMGNT1 (1p34-p33) cause type A3 (MDDGA3; 253280) and type B3 (MDDGB3; 613151).  The muscular dystrophy in B3 is of the limb-girdle type.  POMGNT1 mutations may be associated with congenital glaucoma, retinal dysplasia, and high myopia. Type C3 (MDDGC3; 613157), also with a limb-girdle type of muscular dystrophy (LGMD2O), is caused by mutations in POMGNT1 as well.

FKTN mutations cause type A4 MDDG (MDDGA4; 253800) associated with the Fukuyama type of congenital muscular dystrophy but they can also cause type B4 (MDDGB4; 613152) which does not have mental retardation, and type C4 (MDDGC4; 611588) with seizures and a limb-girdle type (LGMD2M) of muscular dystrophy.

Types A5 (MDDG5A; 613153) and B5 (MDDGB5; 606612) are the result of mutations in the FKRP gene (19q13.3).  Of the two the latter is the less severe and the muscular dystrophy is of the limb-girdle type.  The eyes may be microphthalmic and have retinal pigmentary changes and congenital glaucoma.

Type A6 (MDDGA6; 613154) and B6 (MGGDB6; 608840) are caused by mutations in the LARGE gene (22q12.3).  MDDGA7, or type A7 (614643) results from homozygous or compound heterozygous mutations in the ISPD gene.

Treatment Options

No effective treatment is available but early indications are that FKRP gene therapy restores functional glycosylation and improves muscle functions.

References

Xu L, Lu PJ, Wang CH, Keramaris E, Qiao C, Xiao B, Blake DJ, Xiao X, Lu QL. Adeno-associated virus 9 mediated FKRP gene therapy restores functional glycosylation of α-dystroglycan and improves muscle functions. Mol Ther. 2013 Jul 2. PubMed PMID: 23817215.

PubMed ID: 
23817215

Mercuri E, Messina S, Bruno C, Mora M, Pegoraro E, Comi GP, D'Amico A, Aiello C, Biancheri R, Berardinelli A, Boffi P, Cassandrini D, Laverda A, Moggio M, Morandi L, Moroni I, Pane M, Pezzani R, Pichiecchio A, Pini A, Minetti C, Mongini T, Mottarelli E, Ricci E, Ruggieri A, Saredi S, Scuderi C, Tessa A, Toscano A, Tortorella G, Trevisan CP, Uggetti C, Vasco G, Santorelli FM, Bertini E. Congenital muscular dystrophies with defective glycosylation of dystroglycan: a population study. Neurology. 2009 May 26;72(21):1802-9.

PubMed ID: 
19299310

Vuillaumier-Barrot S, Quijano-Roy S, Bouchet-Seraphin C, Maugenre S, Peudenier S, Van den Bergh P, Marcorelles P, Avila-Smirnow D, Chelbi M, Romero NB, Carlier RY, Estournet B, Guicheney P, Seta N. Four Caucasian patients with mutations in the fukutin gene and variable clinical phenotype. Neuromuscul Disord. 2009 Mar;19(3):182-8.

PubMed ID: 
19179078

Cormand B, Pihko H, Bayés M, Valanne L, Santavuori P, Talim B, Gershoni-Baruch R, Ahmad A, van Bokhoven H, Brunner HG, Voit T, Topaloglu H, Dobyns WB, Lehesjoki AE. Clinical and genetic distinction between Walker-Warburg syndrome and muscle-eye-brain disease. Neurology. 2001 Apr 24;56(8):1059-69.

PubMed ID: 
11320179

Warburg Micro Syndrome

Clinical Characteristics

Ocular Features

Microphthalmia with microcornea, lens opacities, small and unresponsive pupils, and optic atrophy are the outstanding ocular features of this syndrome. Some but not all have ERG evidence of rod and cone dysfunction.  The VEP is usually abnormal.  Short palpebral fissures have been described. 

Systemic Features

Patients with the micro syndrome have many somatic and neurologic abnormalities.  Some degree of psychomotor retardation and developmental delays is common.  Both spasticity and hypotonia have been described.  Some patients have seizures.  Facial hypertrichosis, anteverted ears, and a broad nasal bridge are often noted.   There may be absence of the corpus callosum while diffuse cortical and subcortical atrophy and pachygyria may be evident on MRI imaging.  Hypogenitalism in males has been described.  Microcephaly is inconsistently present. 

Genetics

This disorder is caused by homozygous mutations in the RAB3GAP1 gene (2q21.3) and therefore inherited in an autosomal recessive pattern. 

Treatment Options

No effective treatment is available.  Vision remains subnormal even after cataracts are removed. 

References

Morris-Rosendahl DJ, Segel R, Born AP, Conrad C, Loeys B, Brooks SS, Müller L,Zeschnigk C, Botti C, Rabinowitz R, Uyanik G, Crocq MA, Kraus U, Degen I, Faes F. New RAB3GAP1 mutations in patients with Warburg Micro Syndrome from different ethnic backgrounds and a possible founder effect in the Danish. Eur J Hum Genet. 2010 Oct;18(10):1100-6.

PubMed ID: 
20512159

Abdel-Salam GM, Hassan NA, Kayed HF, Aligianis IA. Phenotypic variability in Micro syndrome: report of new cases. Genet Couns. 2007;18(4):423-35.

PubMed ID: 
18286824

Warburg M, Sjö O, Fledelius HC, Pedersen SA. Autosomal recessive microcephaly, microcornea, congenital cataract, mental retardation, optic atrophy, and hypogenitalism. Micro syndrome. Am J Dis Child. 1993 Dec;147(12):1309-12.

PubMed ID: 
8249951

Neurodegeneration with Brain Iron Accumulation

Clinical Characteristics

Ocular Features

Optic atrophy is a major ocular feature and the primary cause of visual impairment.  A minority (25%) of patients also have a diffuse fleck retinopathy with a bull’s eye maculopathy.  Later the retinopathy may resemble retinitis pigmentosa with a bone spicule pattern. Nystagmus is often present.  These signs usually follow systemic signs such as difficulties in locomotion.  An apraxia of eyelid opening has been noted and some patients have blepharospasm. 

Systemic Features

This is a progressive disorder of the basal ganglia with prominent symptoms of extrapyramidal dysfunction.  Onset is in early childhood or in the neonatal period with delayed development and sometimes mental retardation.  Choreoathetoid writhing movements, stuttering, dysphagia, muscle rigidity, and intermittent dystonia are prominent features.  Seizures are uncommon.  Older individuals may exhibit dementia and ambulation is eventually impaired.  The MRI usually shows an area of hyperintensity in the medial globus pallidus that has been called the ‘eye of the tiger’ sign but this is not pathognomonic.  Axonal degeneration with accumulation of spheroidal inclusions can be seen histologically. 

Genetics

The title of this disorder ‘neurodegeneration with brain iron accumulation’ actually refers to a group of disorders with somewhat common characteristics.  Pentothenate kinase-associated neurodegeneration or NB1A1 (234200) is  the most common of these. 

Types  NBIA2A (256600) and NBIA2B (610217) are caused by mutations in the PLA2G6 gene (22q13.1).  The former can be seen neonatally but usually has its onset in the first two years of life and is sometimes called infantile neuroaxonal dystrophy or Seitelberger disease.  Death may occur before the age of 10 years.  Signs of motor neuron and cerebellar disease are more prominent than in NB1A1. 

NBIA2B has a later onset (4-5 years) and profound sensorimotor impairment but there are many overlapping features and the nosology is confusing.  Mutations in the FTL gene cause yet another form designated NBIA3 (606159) but ocular signs seem to be absent. 

Treatment Options

There is evidence that treatment with deferiprone reduces the amount of iron accumulation in the globus pallidus with motor improvement in at least some patients.  Most patients require supportive care.

References

Abbruzzese G, Cossu G, Balocco M, Marchese R, Murgia D, Melis M, Galanello R, Barella S, Matta G, Ruffinengo U, Bonuccelli U, Forni GL. A pilot trial of deferiprone for neurodegeneration with brain iron accumulation. Haematologica. 2011 Jul 26. [Epub ahead of print]

PubMed ID: 
21791473

Gregory A, Polster BJ, Hayflick SJ. Clinical and genetic delineation of neurodegeneration with brain iron accumulation. J Med Genet. 2009 Feb;46(2):73-80. Review.

PubMed ID: 
18981035

Kurian MA, Morgan NV, MacPherson L, Foster K, Peake D, Gupta R, Philip SG, Hendriksz C, Morton JE, Kingston HM, Rosser EM, Wassmer E, Gissen P, Maher ER. Phenotypic spectrum of neurodegeneration associated with mutations in the PLA2G6 gene (PLAN). Neurology. 2008 Apr 29;70(18):1623-9.

PubMed ID: 
18443314

Hayflick SJ, Westaway SK, Levinson B, Zhou B, Johnson MA, Ching KH, Gitschier J. Genetic, clinical, and radiographic delineation of Hallervorden-Spatz syndrome. N Engl J Med. 2003 Jan 2;348(1):33-40.

PubMed ID: 
12510040

Luckenbach MW, Green WR, Miller NR, Moser HW, Clark AW, Tennekoon G. Ocular clinicopathologic correlation of Hallervorden-Spatz syndrome with acanthocytosis and pigmentary retinopathy. Am J Ophthalmol. 1983 Mar;95(3):369-82.

PubMed ID: 
6829683

Albinism, Oculocutaneous, Type III

Clinical Characteristics

Ocular Features

The irides may be multicolored with the central potion light brown and the peripheral areas blue-gray.  Translucency of a punctate and radial nature is present.  Nystagmus is present in almost all cases and strabismus is present in nearly half.  Visual acuity is in the range of 20/60 to 20/200.   Photophobia is less severe than in other types of oculocutaneous albinism, possibly because the vast majority of individuals (86%) have some pigmentation in the fundus. 

Systemic Features

The hair in dark-skinned people may be medium brown while the skin is often light brown and subject to faint tanning.  However, the hair is often copper-red in color which has given rise to the designation rufous oculocutaneous albinism. 

Genetics

This tyrosinase-positive type of albinism is sometimes called ‘rufous’ (ROCA) or ‘brown’ (BOCA) oculocutaneous albinism and is frequently found in dark-skinned individual such as Africans, African-Americans, and Hispanics.  Like other types it is inherited in an autosomal recessive pattern.  Mutations in the tyrosinase-related protein-1, TYRP1 (9p23), are responsible which seems to lead to an arrest in melanin maturation and a decrease in the amount of insoluble melanin in melanocytes.

Other autosomal recessive types of oculocutaneous albinism are: OCA1 (203100, 606952), OCA2 (203200), and OCA4 (606574). 

Treatment Options

No treatment is available for the hypopigmentation.  However, precautions against excessive sun exposure are advised.  Low vision aids can be helpful. 

References

Gr√∏nskov K, Ek J, Brondum-Nielsen K. Oculocutaneous albinism. Orphanet J Rare Dis. 2007 Nov 2;2:43. Review.

PubMed ID: 
17980020

Manga P, Kromberg JG, Box NF, Sturm RA, Jenkins T, Ramsay M. Rufous oculocutaneous albinism in southern African Blacks is caused by mutations in the TYRP1 gene. Am J Hum Genet. 1997 Nov;61(5):1095-101.

PubMed ID: 
9345097

King RA, Lewis RA, Townsend D, Zelickson A, Olds DP, Brumbaugh J. Brown oculocutaneous albinism. Clinical, ophthalmological, and biochemical characterization. Ophthalmology. 1985 Nov;92(11):1496-505.

PubMed ID: 
3935994