seizures

Mitochondrial DNA Depletion Syndrome 3

Clinical Characteristics
Ocular Features: 

Nystagmus, disconjugate eye movements, and "optic dysplasia" have been noted.

Systemic Features: 

Infants feed poorly which is frequently associated with vomiting, failure to thrive, and growth delay.  They are hypothermic, hypoglycemic, and often jaundiced with signs of liver failure noted between birth and 6 months of age and death by approximately 1 year of age.  Hepatosplenomegaly is present early with abnormal liver enzymes, cholestasis, steatosis, and hepatocellular loss followed by cirrhosis with portal hypertension.  Metabolic acidosis, hyperbilirubinemia, hypoalbuminemia, and hypoglycemia are often present.  Mitochondrial DNA depletion in the liver approaches 84-90%.

All patients have encephalopathic signs with evidence of cerebral atrophy, microcephaly, hypotonia.  Hyperreflexia may be present and some infants have seizures.  Muscle tissue, however, has normal histology and respiratory chain activity.

Genetics

This disorder results from homozygous or compound heterozygous mutations in the DGUOK gene (2p13).

The same gene is mutated in PEOB4 (617070).

Pedigree: 
Autosomal recessive
Treatment
Treatment Options: 

There is no effective treatment.  Liver transplantation in one infant was unsuccessful.  

References
Article Title: 

Cerebral Palsy, Spastic Quadriplegic, 3

Clinical Characteristics
Ocular Features: 

One family with 4 affected sibs has been reported but without detailed information on ophthalmological findings.  Strabismus reported as exotropia in one individual, and "convergent retraction nystagmus" in another was present.  Supranuclear gaze palsy was described in one individual. 

Systemic Features: 

Borderline microcephaly has been reported.  Evidence for global neurologic disease, primarily spasticity, may be present as early as 3 months of age.  Intellectual disability ranges from borderline to severe.  Progression is somewhat variable but by the second decade there may be sufficient spastic quadriparesis and cognitive impairment that full time assistive care is required.  Dysarthria and dysphagia are also features and gastrostomy feeding tubes may be required to maintain nutrition.  Seizures are uncommon.

The MRI does not show major structural abnormalities and an EEG in one patient revealed only bifrontal spike-waves.

Genetics

This condition is caused by homozygous mutations in the ADD3 gene (10q24).

Pedigree: 
Autosomal recessive
Treatment
Treatment Options: 

No treatment is known.

References
Article Title: 

Mutations in gamma adducin are associated with inherited cerebral palsy

Kruer MC, Jepperson T, Dutta S, Steiner RD, Cottenie E, Sanford L, Merkens M, Russman BS, Blasco PA, Fan G, Pollock J, Green S, Woltjer RL, Mooney C, Kretzschmar D, Paisan-Ruiz C, Houlden H. Mutations in gamma adducin are associated with inherited cerebral palsy. Ann Neurol. 2013 Dec;74(6):805-14.

PubMed ID: 
23836506

Heart and Brain Malformation Syndrome

Clinical Characteristics
Ocular Features: 

Microphthalmia is the cardinal ocular malformation.  Hypertelorism has been described.  Poor vision without further description has also been reported.   

Systemic Features: 

The ears are low-set, malformed, and posteriorly rotated.  The forehead is prominent and there is usually a wide anterior fontanel.  The nasal bridge is wide and frequently depressed while the lower lip is full and may be everted and split.  The palate is highly arched.  Physical growth is slow.  A ventricular septal defect is often present while the valves are hypoplastic and the aortic arch can be interrupted.

Microcephaly is often present and there may a profound delay in psychomotor development with truncal hypotonia and hyperreflexia in the limbs.   Brain imaging shows generalized atrophy with decreased myelination.  Cerebellar vermis hypoplasia has been reported.  Two of 5 patients were reported to have Dandy-Walker malformations, and a thin corpus callosum.  Seizures may occur.

Genetics

Homozygous mutations in the SMG9 gene (19q13.31) are responsible for this condition so far reported in 5 individuals in two unrelated consanguineous Arab families.

Pedigree: 
Autosomal recessive
Treatment
Treatment Options: 

No treatment has been reported.

References
Article Title: 

Mutations in SMG9, Encoding an Essential Component of Nonsense-Mediated Decay Machinery, Cause a Multiple Congenital Anomaly Syndrome in Humans and Mice

Shaheen R, Anazi S, Ben-Omran T, Seidahmed MZ, Caddle LB, Palmer K, Ali R, Alshidi T, Hagos S, Goodwin L, Hashem M, Wakil SM, Abouelhoda M, Colak D, Murray SA, Alkuraya FS. Mutations in SMG9, Encoding an Essential Component of Nonsense-Mediated Decay Machinery, Cause a Multiple Congenital Anomaly Syndrome in Humans and Mice. Am J Hum Genet. 2016 Apr 7;98(4):643-52.

PubMed ID: 
27018474

Spinocerebellar Ataxia 42

Clinical Characteristics
Ocular Features: 

 Saccadic eye movements with nystagmus and diplopia have been reported (7 of 10 reported patients).

Systemic Features: 

Cerebellar signs usually have their onset in midlife or later with slow progression.  Most patients are mildly to moderately disabled.  Dysarthria, dysphagia, and a spastic gait are experienced by the majority of individuals.  Hyperreflexia and a positive Babinski sign are commonly presently.  Mild cognitive impairment and depression have been seen in a minority of patients.

Brain MRIs show cerebellar hemispheric and vermian atrophy.  The cerebral cortex appeared histologically normal in one deceased patient.

Genetics

This disorder is caused by heterozygous mutations in the CACNA1G gene (17q21.33).

Pedigree: 
Autosomal dominant
Treatment
Treatment Options: 

No treatment has been reported.

References
Article Title: 

Encephalocraniocutaneous Lipomatosis

Clinical Characteristics
Ocular Features: 

Ocular choristomas of the periocular tissue such as epibulbar dermoids or lipodermoids are seen in 80% of individuals.  Some degree of microphthalmia, a 'hypertrophic' conjunctiva, and sclerocornea have been reported.  The pupils are small and iris hypoplasia with anterior chamber anomalies has been described.  The macular reflex can be absent and colobomas of the eyelids (and rarely uveal tract) have been seen.

Systemic Features: 

Preauricular skin tags may be present.   Fatty tissue nevi associated with alopecia as well as frontotemporal or zygomatic subcutaneous fatty lipomas, and focal dermal hypoplasia are seen externally in many patients.   Coarctation and/or hypoplasia of the thoracic aorta along with aortic valve anomalies are sometimes present.

Intracranial and intraspinal lipomas are present in over 60% of individuals.  Arachnoid cysts with ventricular enlargement, and leptomeningeal angiomatosis are frequently present.  Jawbone cysts and tumors are common. The skull and heart may also have lipomas.  Seizures and some intellectual disability have been diagnosed in many affected individuals but a third or more have normal intellect.  The affected cortex may calcify later in life.

Genetics

ECCL is considered to result from postzygotic activating mutations in the FGFR1 gene (8p11.23) resulting in a mosaic distribution.  This may help explain the highly variable and widespread distribution of skin and CNS lesions.  A 5-year-old female with an affected father and paternal grandmother have been reported suggesting autosomal dominant inheritance.

Mutations in the same gene have been found in Pfeiffer syndrome (101600).

Pedigree: 
Autosomal dominant
Treatment
Treatment Options: 

There is no treatment for the overall condition but selective removal of tumors with cosmetic and pressure consequences should be considered.

References
Article Title: 

Mosaic Activating Mutations in FGFR1 Cause Encephalocraniocutaneous Lipomatosis

Bennett JT, Tan TY, Alcantara D, Tetrault M, Timms AE, Jensen D, Collins S, Nowaczyk MJ, Lindhurst MJ, Christensen KM, Braddock SR, Brandling-Bennett H, Hennekam RC, Chung B, Lehman A, Su J, Ng S, Amor DJ; University of Washington Center for Mendelian Genomics; Care4Rare Canada Consortium, Majewski J, Biesecker LG, Boycott KM, Dobyns WB, O'Driscoll M, Moog U, McDonell LM. Mosaic Activating Mutations in FGFR1 Cause Encephalocraniocutaneous Lipomatosis. Am J Hum Genet. 2016 Mar 3;98(3):579-87.

PubMed ID: 
26942290

Hyperphosphatasia with Mental Retardation Syndrome 6

Clinical Characteristics
Ocular Features: 

Congenital cataracts may be present.  The eyes appear deeply-set and strabismus has been seen in severely affected cases.   

Systemic Features: 

Two families have been reported.  The range of severity in symptoms is wide.  Birth may occur prematurely especially in the presence of polyhydramnios.  Postnatal development can be complicated by seizures, chronic lung disease, developmental regression, and renal disease.  Poor growth secondary to feeding difficulties have been reported.  Death can occur in early childhood.

Dysmorphic features include a short neck, bitemporal narrowing, depressed nasal bridge, and proximal limb shortening.  Osteopenia, flexion contractures, and hip dysplasia may be present.  Dilatation of the renal collecting system with increased echogenicity have been reported.  Creatine kinase and serum alkaline phosphatase may be increased and muscle histology shows small, atrophic fibers with increased fibrosis and considerable variations in fiber size.

Genetics

Homozygous mutations in the PIGY gene (4q22.1) resulting in deficiencies of glycosylphosphatidylinositol synthesis have been associated with this condition.  

Pedigree: 
Autosomal recessive
Treatment
Treatment Options: 

No effective treatment has been reported.

References
Article Title: 

Mutations in PIGY: expanding the phenotype of inherited glycosylphosphatidylinositol deficiencies

Ilkovski B, Pagnamenta AT, O'Grady GL, Kinoshita T, Howard MF, Lek M, Thomas B, Turner A, Christodoulou J, Sillence D, Knight SJ, Popitsch N, Keays DA, Anzilotti C, Goriely A, Waddell LB, Brilot F, North KN, Kanzawa N, Macarthur DG, Taylor JC, Kini U, Murakami Y, Clarke NF. Mutations in PIGY: expanding the phenotype of inherited glycosylphosphatidylinositol deficiencies. Hum Mol Genet. 2015 Nov 1;24(21):6146-59.

PubMed ID: 
26293662

Hypotonia, Infantile, with Psychomotor Retardation and Characteristic Facies 3

Clinical Characteristics
Ocular Features: 

Deep-set eyes with highly arched eyebrows have been described and poor fixation can be present.  Cortical visual impairment has been described.

Systemic Features: 

The neurologic abnormalities become evident soon after birth.  Hypotonia and decreased reflexes may be present early and often there is little psychomotor development subsequently.  Some patients have no or very little speech and may never sit, stand, or walk.  However, there is considerable variation in the clinical picture and other individuals are able to walk and may live into the third decade.  Brain imaging reveals a variety of abnormalities including cerebellar and cerebral hypoplasia.  Respiratory difficulties and poor feeding are often present.

The facial dysmorphism may include brachycephaly with a broad forehead and narrowing of the temporal regions.  The nose may be small and the mouth appears large in the presence of micrognathia and a thin upper lip.

Genetics

This is an autosomal recessive condition as the result of homozygous or compound heterozygous mutations in the TBCK gene (4q24). 

Other similar conditions include IHPRF2 (616801) (with homozygous mutations in UNC80 and IHPRF1 (615419) (with homozygous mutations in NALCN) whose ocular features may include strabismus, nystagmus, and poor visual fixation.    

Pedigree: 
Autosomal recessive
Treatment
Treatment Options: 

No treatment is available.

References
Article Title: 

Mutations in TBCK, Encoding TBC1-Domain-Containing Kinase, Lead to a Recognizable Syndrome of Intellectual Disability and Hypotonia

Bhoj EJ, Li D, Harr M, Edvardson S, Elpeleg O, Chisholm E, Juusola J, Douglas G, Guillen Sacoto MJ, Siquier-Pernet K, Saadi A, Bole-Feysot C, Nitschke P, Narravula A, Walke M, Horner MB, Day-Salvatore DL, Jayakar P, Vergano SA, Tarnopolsky MA, Hegde M, Colleaux L, Crino P, Hakonarson H. Mutations in TBCK, Encoding TBC1-Domain-Containing Kinase, Lead to a Recognizable Syndrome of Intellectual Disability and Hypotonia. Am J Hum Genet. 2016 Apr 7;98(4):782-8.

PubMed ID: 
27040691

Recessive Inactivating Mutations in TBCK, Encoding a Rab GTPase-Activating Protein, Cause Severe Infantile Syndromic Encephalopathy

Chong JX, Caputo V, Phelps IG, Stella L, Worgan L, Dempsey JC, Nguyen A, Leuzzi V, Webster R, Pizzuti A, Marvin CT, Ishak GE, Ardern-Holmes S, Richmond Z; University of Washington Center for Mendelian Genomics, Bamshad MJ, Ortiz-Gonzalez XR, Tartaglia M, Chopra M, Doherty D. Recessive Inactivating Mutations in TBCK, Encoding a Rab GTPase-Activating Protein, Cause Severe Infantile Syndromic Encephalopathy. Am J Hum Genet. 2016 Apr 7;98(4):772-81.

PubMed ID: 
27040692

Eye Movement Disorders with CACNA1A Mutations

Clinical Characteristics
Ocular Features: 

Eye movement disorders secondary to CACNA1A mutations include congenital nystagmus, abnormal saccades and paroxysmal tonic upgaze and can be early indicators of underlying neurologic disease.  The median age of presentation in one series was 1.2 years.

Systemic Features: 

Eye movement disorders form a group of conditions that may occur in isolation but can also be associated with underlying neurological disease (vida infra).

Genetics

Heterozygous mutations in the CACNA1A gene (19p13.13) have been associated with a number of conditions including type 2 episodic ataxia (108500), familial hemiplegic migraine 1 (141500), and 2 (602481), spinocerebellar ataxia 6 (183086), and several types of eye movement disorders including congenital nystagmus, abnormal saccades, and paroxysmal tonic upgaze. 

The gene product is a transmembrane pore-forming subunit of a voltage-gated calcium channel expressed abundantly in neuronal tissue.

Pedigree: 
Autosomal dominant
Treatment
Treatment Options: 

The use of calcium channel blockers may have some benefit in preventing severe hemiplegic migraine.

References
Article Title: 

Spastic Paraplegia with Psychomotor Retardation and Seizures

Clinical Characteristics
Ocular Features: 

The eyes are usually deeply set.  Nothing is known regarding visual acuity.  Strabismus is a common feature.  Retinal dystrophy (not further described) has been reported in 4 of 8 patients described.  The ERG in one individual was read as consistent with cone-rod dystrophy.

Systemic Features: 

Newborns are hypotonic and severe psychomotor retardation is evident a few months later.  Truncal ataxia and progressive lower limb spasticity are seen later.  Mobility is significantly impaired and many individuals are confined to bed or a wheelchair and never walk.  Dysarthria is frequently present and some individuals have a neurosensory hearing loss.  Myoclonic seizures may be evident.  Kyphoscoliosis, macrocephaly, and various foot deformities have been described.

CT scans of the brain may show generalized cerebral atrophy and a hypoplastic corpus callosum.  The ventricles may be enlarged and the EEG confirms the occurrence of myoclonic as well as tonic-clonic and focal epilepsy.

Genetics

This is an autosomal recessive disorder caused by homozygous or compound heterozygous mutations in the HACE1 gene (6q16).

Pedigree: 
Autosomal recessive
Treatment
Treatment Options: 

No treatment has been reported for this condition but physical therapy and assistive devices such as hearing and visual aids may be helpful.

References
Article Title: 

DDD study. Discovery of four recessive developmental disorders using probabilistic genotype and phenotype matching among 4,125 families

Akawi N, McRae J, Ansari M, Balasubramanian M, Blyth M, Brady AF, Clayton S, Cole T, Deshpande C, Fitzgerald TW, Foulds N, Francis R, Gabriel G, Gerety SS, Goodship J, Hobson E, Jones WD, Joss S, King D, Klena N, Kumar A, Lees M, Lelliott C, Lord J, McMullan D, O'Regan M, Osio D, Piombo V, Prigmore E, Rajan D, Rosser E, Sifrim A, Smith A, Swaminathan GJ, Turnpenny P, Whitworth J, Wright CF, Firth HV, Barrett JC, Lo CW, FitzPatrick DR, Hurles ME; DDD study. Discovery of four recessive developmental disorders using probabilistic genotype and phenotype matching among 4,125 families. Nat Genet. 2015 Nov;47(11):1363-9.

PubMed ID: 
26437029

HACE1 deficiency causes an autosomal recessive neurodevelopmental syndrome

Hollstein R, Parry DA, Nalbach L, Logan CV, Strom TM, Hartill VL, Carr IM, Korenke GC, Uppal S, Ahmed M, Wieland T, Markham AF, Bennett CP, Gillessen-Kaesbach G, Sheridan EG, Kaiser FJ, Bonthron DT. HACE1 deficiency causes an autosomal recessive neurodevelopmental syndrome. J Med Genet. 2015 Dec;52(12):797-803.

PubMed ID: 
26424145

Optic Atrophy 10

Clinical Characteristics
Ocular Features: 

Low vision is noted in early childhood without systemic symptoms.  The optic nerves appear pale (age of onset uncertain).  The retinal nerve fiber layer may be reduced in thickness in all quadrants but only segmentally in some individuals.  No VEP can be recorded.  On brain MRI examination the optic tracts are thin.  The appearance of the optic nerve is consistent with mild hypoplasia in some patients.

Systemic Features: 

Some patients have ataxia, cognitive deficits, and seizures.  A brother and sister from a consanguineous Moroccan family and two unrelated individuals have been reported.  

Genetics

This autosomal recessive condition is caused by homozygous or compound heterozygous mutations in the RTN4IP1 gene.

Pedigree: 
Autosomal recessive
Treatment
Treatment Options: 

No treatment is known.

References
Article Title: 

Recessive Mutations in RTN4IP1 Cause Isolated and Syndromic Optic Neuropathies

Angebault C, Guichet PO, Talmat-Amar Y, Charif M, Gerber S, Fares-Taie L, Gueguen N, Halloy F, Moore D, Amati-Bonneau P, Manes G, Hebrard M, Bocquet B, Quiles M, Piro-Megy C, Teigell M, Delettre C, Rossel M, Meunier I, Preising M, Lorenz B, Carelli V, Chinnery PF, Yu-Wai-Man P, Kaplan J, Roubertie A, Barakat A, Bonneau D, Reynier P, Rozet JM, Bomont P, Hamel CP, Lenaers G. Recessive Mutations in RTN4IP1 Cause Isolated and Syndromic Optic Neuropathies. Am J Hum Genet. 2015 Nov 5;97(5):754-60. 

PubMed ID: 
26593267

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