SPATA7 gene

Overview

Gene (OMIM no.)
Function of gene/protein
  • Protein: Spermatogenesis-associated protein 7
  • Two isoforms due to alternative splicing
  • Expressed in high levels in the brain, retina and testes
  • Cilia protein localised at the photoreceptor connecting cilium and in the RPE
  • Involved in RPGRIP1 localisation and protein trafficking
Clinical phenotype
(OMIM phenotype no.)
Inheritance
  • Autosomal recessive
Signs for LCA
  • Early onset visual impairment with poor visual pursuit (during infancy)
  • Roving nystagmus
  • Amaurotic pupils
  • Normal appearing fundus initially
  • Progresses to severe widespread RPE atrophy with minimal intra-retinal pigmentation
  • Relative parafoveal preservation
  • Optic disc pallor
  • Vessel attenuation
  • Keratoconus and early onset cataract reported
Signs for RP
  • Milder EOSRD phenotype with minimal/no nystagmus due to relatively preserved cone function initially
  • Vessel attenuation
  • Widespread RPE degeneration
  • Bone-spicule pigmentation in the mid-periphery (sparse)
  • Optic disc pallor
Visual functionLCA:
  • Poor visual function from infancy in LCA cases
  • VA usually worse than 6/60 (LogMAR 1.00)
  • Severely constricted VF (central 5° on GVF)
  • Stable/slowly progressive
EOSRD:
  • Nyctalopia during early childhood
  • Relatively preserved VA initially
  • Progressive VA and VF loss
  • BCVA deteriorates to 6/60 (LogMAR 1.00) or worse over time
  • Visual field restriction to central 5° on GVF
Systemic features
  • No extraocular features reported
Key investigations
  • ERG: absent responses/severe rod-cone dystrophy
  • FAF: Parafoveal ring of increased AF surrounded by diffuse hypo-AF beyond the ring
  • OCT: Preserved foveal ellipsoid zone but outer retinal loss parafoveally
Molecular diagnosisNext generation sequencing
  • Targeted gene panels (retinal)
  • Whole exome sequencing
  • Whole genome sequencing
Management
Therapies under research
Further information

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References

  1.  Eblimit A, Agrawal SA, Thomas K, et al. Conditional loss of Spata7 in photoreceptors causes progressive retinal degeneration in mice [published correction appears in Exp Eye Res. 2018 Mar 23;171:119]. Exp Eye Res. 2018;166:120-130
  2.  Eblimit A, Agrawal SA, Thomas K, et al. Corrigendum to “Conditional loss of Spata7 in photoreceptors causes progressive retinal degeneration in mice” [Exp. Eye Res. 166 (2018) 120-130]. Exp Eye Res. 2018;171:119
  3.  Eblimit A, Nguyen TM, Chen Y, et al. Spata7 is a retinal ciliopathy gene critical for correct RPGRIP1 localization and protein trafficking in the retina. Hum Mol Genet. 2015;24(6):1584-1601
  4.  Zahid S, Branham K, Schlegel D, et al. Retinal Dystrophy Gene Atlas. Springer; 2018
  5.  Mackay DS, Ocaka LA, Borman AD, et al. Screening of SPATA7 in patients with Leber congenital amaurosis and severe childhood-onset retinal dystrophy reveals disease-causing mutations. Invest Ophthalmol Vis Sci. 2011;52(6):3032-3038
  6.  Wang H, den Hollander AI, Moayedi Y, et al. Mutations in SPATA7 cause Leber congenital amaurosis and juvenile retinitis pigmentosa [published correction appears in Am J Hum Genet. 2010 Feb;86(2):293. Abboud, Emad B [added]; Al-Rajhi, Ali A [added]]. Am J Hum Genet. 2009;84(3):380-387
  7.  Perrault I, Hanein S, Gerard X, et al. Spectrum of SPATA7 mutations in Leber congenital amaurosis and delineation of the associated phenotype. Hum Mutat. 2010;31(3):E1241-E1250

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Updated on November 30, 2020
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