dysmetria

Myopathy, Mitochondrial Anomalies, and Ataxia

Clinical Characteristics
Ocular Features: 

Ocular findings are variable.  One of three individuals with compound heterozygous mutations had a pigmentary retinopathy with pallor of the optic nerve but no visual abnormalities.  Her sister had only optic nerve pallor.  The eyes are described as "small" and "close-set".

No ocular findings were reported for the family with autosomal dominant inheritance.

Systemic Features: 

Ataxia, short stature, and gait difficulties from an early age are consistent findings.  Some patients are never able to walk.  Motor development is generally delayed.  Truncal and limb ataxia is a feature.  Some degree of intellectual disability is generally present and speech is often delayed.  

The face is long with a myopathic appearance.  Both micrognathia and a prominent jaw may be seen.  The palate is highly arched.  Patients are described as hypotonic and there is generalized muscle weakness both proximal and distal.  Distal sensory impairment has been described in the family with presumed dominant inheritance and there may be psychiatric symptoms of anxiety, depression, and schizophrenia.  Dysmetria with dysdiadochokinesis is often present and a fine intention tremor has been observed.

Mitochondria in fibroblasts exhibit abnormal dynamics and occur in a fragmented network.  Muscle biopsies reveal changes consistent with myopathy.  Serum creatine kinase may be elevated.

Genetics

Compound heterozygous mutations in the MSTO1 gene (1q22) have been found in two families with 3 affected individuals suggesting autosomal recessive inheritance.  In a third family, heterozygous mutations in the same gene were found in a mother and 3 of her adult children, consistent with autosomal dominant transmission.

Pedigree: 
Autosomal dominant
Autosomal recessive
Treatment
Treatment Options: 

No treatment has been reported.

References
Article Title: 

Spastic Paraplegia 75

Clinical Characteristics
Ocular Features: 

Nystagmus with optic atrophy is usually present and one individual had glaucoma. 

Systemic Features: 

This is an early-onset and progressive neurodegenerative disorder.  Hypotonia may be present at birth.  A spastic gait and difficulty walking is noted in early childhood and most individuals never walk unassisted. Yong adults have spastic paresis with extensor plantar responses and clonus has been reported.  Distal muscle atrophy in the lower extremities has been noted.  Speech is dysarthric.  Brain imaging has been normal in some patients whereas others have mild atrophy of the cerebellum and the corpus callosum.  Cognitive impairment is variable with some individuals showing poor school performance while others are described as mentally retarded.

Genetics

Homozygous mutations in the MAG gene (19q13.12) are responsible for this disorder.

Pedigree: 
Autosomal recessive
Treatment
Treatment Options: 

No effective treatment has been reported although physical therapy may be helpful. Special education, speech and physical therapy, and low vision devices might also be of benefit.

References
Article Title: 

Myelin-associated glycoprotein gene mutation causes Pelizaeus-Merzbacher disease-like disorder

Lossos A, Elazar N, Lerer I, Schueler-Furman O, Fellig Y, Glick B, Zimmerman BE, Azulay H, Dotan S, Goldberg S, Gomori JM, Ponger P, Newman JP, Marreed H, Steck AJ, Schaeren-Wiemers N, Mor N, Harel M, Geiger T, Eshed-Eisenbach Y, Meiner V, Peles E. Myelin-associated glycoprotein gene mutation causes Pelizaeus-Merzbacher disease-like disorder. Brain. 2015 Sep;138(Pt 9):2521-36.

PubMed ID: 
26179919

Exome sequencing links corticospinal motor neuron disease to common neurodegenerative disorders

Novarino G, Fenstermaker AG, Zaki MS, Hofree M, Silhavy JL, Heiberg AD, Abdellateef M, Rosti B, Scott E, Mansour L, Masri A, Kayserili H, Al-Aama JY, Abdel-Salam GM, Karminejad A, Kara M, Kara B, Bozorgmehri B, Ben-Omran T, Mojahedi F, Mahmoud IG, Bouslam N, Bouhouche A, Benomar A, Hanein S, Raymond L,Forlani S, Mascaro M, Selim L, Shehata N, Al-Allawi N, Bindu PS, Azam M, Gunel M, Caglayan A, Bilguvar K, Tolun A, Issa MY, Schroth J, Spencer EG, Rosti RO, Akizu N, Vaux KK, Johansen A, Koh AA, Megahed H, Durr A, Brice A, Stevanin G, Gabriel SB, Ideker T, Gleeson JG. Exome sequencing links corticospinal motor neuron disease to common neurodegenerative disorders. Science. 2014 Jan 31;343(6170):506-11.

PubMed ID: 
24482476

Spinocerebellar Ataxia 18

Clinical Characteristics
Ocular Features: 

Ocular signs in SCAR18 include nystagmus, oculomotor apraxia, and optic atrophy.  The nystagmus may be rotatory or horizontal and can be gaze-evoked.  Some patients have intermittent and tonic upgaze.  Visual acuity has not been reported.

Systemic Features: 

Patients are developmentally delayed and have intellectual disability.  These features do not seem to be progressive.  Ataxia, both truncal and cerebellar, is present.  Mobility is impaired from early childhood and eventually requires assistance.   Joint contractures sometimes develop and patients can be wheelchair-bound by the second decade.  Dysarthric speech is common.  No dysmorphic facial features are present.

Brain imaging shows progressive cerebellar and sometimes cerebral atrophy.

Genetics

This autosomal recessive disorder results from homozygous deletions in the GRID2 gene (4q22).  This gene codes for a subunit of the glutamate receptor channel and is thought to be selectively expressed in the Purkinje cells of the cerebellum.

Pedigree: 
Autosomal recessive
Treatment
Treatment Options: 

No treatment has been reported.  However, physical therapy, assistive devices for mobility, and low vision aids may be helpful.

References
Article Title: 

Chorioretinopathy, Ataxia, and Hypogonadism

Clinical Characteristics
Ocular Features: 

The retinal pigment epithelium changes may be seen as early as the first decade of life with pigment deposition resembling bone spicules.  These changes as well as atrophy of the choriocapillaris are most apparent in the posterior pole and extend into the midperiphery.  Retinal vessels may be attenuated.  Progressive loss of vision, dyschromatopsia, and photophobia are the primary ocular symptoms. Night blindness and constricted visual fields are noted by some patients.  The ERG shows subnormal and sometimes absent photopic and scotopic responses.  Nystagmus is present in more than half of individuals. 

Systemic Features: 

Difficulties with balance, intention tremors, and scanning speech are evident in adolescence or early adult life.  Cerebellar ataxia is present in nearly 40 percent of individuals.  However, there is marked variability in the rate of progression.  Many patients have atrophy of the superior and dorsal areas of the cerebellar vermis and atrophy of the cerebellar hemispheres as noted on MRIs. Hypogonadotrophic hypogonadism is a feature with delayed puberty noted in 26 percent.  In the absence of exogenous hormone administration, secondary sexual characteristics fail to develop.

Genetics

Autosomal recessive inheritance has been suggested on the basis of consanguinity in three families, multiple affected sibs born to normal parents, and a 1:1 sex ratio.  Homozygous and compound heterozygous mutations in PNPLA6 (19p13.2) have been found in several patients.

Mutations in PNPLA6 occur in other conditions including a form of Bardet-Biedl Syndrome (209900), and Trichomegaly Plus Syndrome (275400), in this database.

 

Pedigree: 
Autosomal recessive
Treatment
Treatment Options: 

The use of appropriate hormones can stimulate the development of normal secondary sexual characteristics and may restore reproductive function.   At least two female patients gave birth to a child following hormone substitution.

Low vision aids could be helpful in selected patients.

References
Article Title: 

Boucher-Neuhäuser syndrome: cerebellar degeneration, chorioretinal dystrophy and hypogonadotropic hypogonadism: two novel cases and a review of 40 cases from the literature

Tarnutzer AA, Gerth-Kahlert C, Timmann D, Chang DI, Harmuth F, Bauer P, Straumann D, Synofzik M. Boucher-Neuhauser syndrome: cerebellar degeneration, chorioretinal dystrophy and hypogonadotropic hypogonadism: two novel cases and a review of 40 cases from the literature. J Neurol. 2014 Oct 31. [Epub ahead of print].

PubMed ID: 
25359264

PNPLA6 mutations cause Boucher-Neuhauser and Gordon Holmes syndromes as part of a broad neurodegenerative spectrum

Synofzik M, Gonzalez MA, Lourenco CM, Coutelier M, Haack TB, Rebelo A, Hannequin D, Strom TM, Prokisch H, Kernstock C, Durr A, Schols L, Lima-Martinez MM, Farooq A, Schule R, Stevanin G, Marques W Jr, Zuchner S. PNPLA6 mutations cause Boucher-Neuhauser and Gordon Holmes syndromes as part of a broad neurodegenerative spectrum. Brain. 2013 Dec 19. [Epub ahead of print].

PubMed ID: 
24355708
Subscribe to RSS - dysmetria