chorioretinopathy

Chorioretinopathy with Microcephaly 3

Clinical Characteristics
Ocular Features: 

The eyes are not notably small although several patients have been reported to have significant hyperopia.  Vision can be impaired and some individuals have early-onset nystagmus.  The ERG responses are attenuated and may be absent.  The retina is dysplastic with multiple atrophic punched-out lesions, attenuated retinal vessels, and sparse pigmentation. Large retinal folds have been described and one patient developed a retinal detachment.  Optic atrophy was noted in one individual.

Systemic Features: 

Microcephaly of 3-4 standard deviations below normal is a constant feature.  Motor and language abilities can be mildly delayed and  several patients have had mild learning difficulties.   Brain imaging has been normal in most individuals but a shortened and thin corpus callosum was present in one patient.

Genetics

Family and genetic evidence suggest autosomal recessive inheritance.  Compound heterozygous mutations in the TUBGCP4 gene (15q15.3) code for part of a protein complex involved in microtubule organization.

For a somewhat similar condition with a different mutation involving the same microtubule complex see Chorioretinopathy with Microcephaly 1 (251270).

Pedigree: 
Autosomal recessive
Treatment
Treatment Options: 

Low vision aids may be helpful in selected patients.

References
Article Title: 

Mutations in TUBGCP4 Alter Microtubule Organization via the γ-Tubulin Ring Complex in Autosomal-Recessive Microcephaly with Chorioretinopathy

Scheidecker S, Etard C, Haren L, Stoetzel C, Hull S, Arno G, Plagnol V, Drunat S, Passemard S, Toutain A, Obringer C, Koob M, Geoffroy V, Marion V, Strahle U, Ostergaard P, Verloes A, Merdes A, Moore AT, Dollfus H. Mutations in TUBGCP4 Alter Microtubule Organization via the g-Tubulin Ring Complex in Autosomal-Recessive Microcephaly with Chorioretinopathy. Am J Hum Genet. 2015 Apr 2;96(4):666-74.

PubMed ID: 
25817018

Trichomegaly Plus Syndrome

Clinical Characteristics
Ocular Features: 

Eyelashes are described as ‘long’, and the eyebrows are bushy.  The majority of individuals have poor vision secondary to severe receptor dysfunction.  Night blindness and severe photophobia are features in some cases.  Both retinal and choroidal atrophy have been diagnosed in the first 5 years of life and most patients have a progressive and extensive pigmentary retinopathy.

Systemic Features: 

Scalp alopecia and sparse body hair is common in spite of the trichomegaly of the eyebrows and eyelashes.  Frontal bossing has been noted in some patients.  Pituitary dysfunction is suggested by low growth hormone levels, features of hypogonadotropic hypogonadism, and possibly hypothyroidism.

Some deficit of cognitive function is usually present and a few patients have been described as mentally retarded.  There is evidence of progressive neurological damage both centrally and peripherally. Developmental milestones are often achieved late and some individuals have been observed to regress during the first decade of life.  The peripheral neuropathy includes both sensory and motor components.  Sensory nerve action potentials may be lost in the first decade while early motor functions may regress during the same period.  Several patients have had evidence of progressive cerebellar ataxia.

Genetics

Compund heterozygous mutations in PNPLA6 (19p13.2), coding for neuropathy target esterase, have been found in several patients presumed to have this condition.  Autosomal recessive inheritance has been proposed on the basis of a single family in which an affected brother and sister were born to first cousin parents.   

The relationship of this disorder to that found in two cousins, offspring of consanguineous matings, described as ‘cone-rod congenital amaurosis associated with congenital hypertrichosis: an autosomal recessive condition’ (204110 ) is unknown.  They were described as having visual impairment from birth and profound photophobia.  Fundus changes were minimal with a bull’s eye pattern of pigment changes in the macula described as indicative of a rod-cone congenital amaurosis.  ERG responses were unrecordable.  These individuals apparently did not have other somatic, psychomotor or neurologic deficits.

Mutations in PNPLA6 occur in other conditions including a form of Bardet-Biedl Syndrome (209900), and Boucher-Neuhauser Syndrome (215470) also known as Chorioretinopathy, Ataxia, Hypogonadism Syndrome in this database.

Pedigree: 
Autosomal recessive
Treatment
Treatment Options: 

No treatment is available for this condition although growth hormone and testosterone supplementation have been reported to have the appropriate selective effects.

References
Article Title: 

Neuropathy target esterase impairments cause Oliver-McFarlane and Laurence-Moon syndromes

Hufnagel RB, Arno G, Hein ND, Hersheson J, Prasad M, Anderson Y, Krueger LA, Gregory LC, Stoetzel C, Jaworek TJ, Hull S, Li A, Plagnol V, Willen CM, Morgan TM, Prows CA, Hegde RS, Riazuddin S, Grabowski GA, Richardson RJ, Dieterich K, Huang T, Revesz T, Martinez-Barbera JP, Sisk RA, Jefferies C, Houlden H, Dattani MT, Fink JK, Dollfus H, Moore AT, Ahmed ZM. Neuropathy target esterase impairments cause Oliver-McFarlane and Laurence-Moon syndromes. J Med Genet. 2015 Feb;52(2):85-94.

PubMed ID: 
25480986

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
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