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Giulio Ruberto, Sabrina Signorini, Enza Maria Valente, Mauro Antonini, Federica Ferro, Carmine Tinelli, Paolo Emilio Bianchi, Umberto Balottin, Chiara Bertone; RELATIONSHIP BETWEEN GENOTYPE AND ELECTROPHISIOLOGY ASSESSED BY ELECTRORETINOGRAM AND VISUAL EVOKED POTENTIALS IN 44 YOUNG PEOPLE AFFECTED BY JOUBERT SYNDROME. Invest. Ophthalmol. Vis. Sci. 2015;56(7 ):762.
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© ARVO (1962-2015); The Authors (2016-present)
Joubert syndrome (JS) is a rare autosomal recessive congenital malformation of the brainstem and cerebellar vermis. It can be associated with visual system anomalies and oculomotor system defects. Congenital anomalies, implying also retinal dystrophy in a percentage, related with this diseases, are increasingly found in the last years. The aim of the present study is to correlate the genetic findings of the JS with the electrophysiology results.
We show the results of a pluri-annual follow-up in a large cohort of children affected by JS. 44 infants, mean age 8,52±5,06 years, were assessed for genetic mutations. All the children underwent a complete ophthalmologic and neuropsychiatric assessment. In 37 subjects electrophysiologic tests were performed via electroretinogram( ERG) and visual evoked potentials (VEP) done at five spatial frequencies ( from 300 to 15 minutes of arc) registered in awake conditions. Eight infants had electroretinogram achieved under anaesthesia. The results of latencies and amplitudes in ERG and VEP as well were matched with the genetic outcomes.
Mutations were found in 29 on 44 subjects. Mutation in CEP290 was found in 9 children, mutations in INPP5,TMEM216,RPGRIP1L, AHI1, C5orf42, KIF7, TCTN1, NPHP1(EX2), in 4,4,3, 2,2,1,1,1,1,1 children respectively. Fundus signs of retinal dystrophy were established in 19 subjects. ERG amplitudes were lower in both “a” and “b” wave amplitudes in JS with mutation respect the JS without . In the VEP, a significant “p” ( 0.002) was seen in the 120’ spatial frequency amplitude. The 15’ spatial frequency was not perceived in the affected subjects with mutations. The ERG done under anaesthesia showed significant “p” values in all the amplitudes matched with a normal children sample.
Genetic and electrophysiologic follow-up in JS may aid to separate children affected or not by retinal dystrophy. The electrophysiology alone can identify, in the early stages of the disease, if a photoreceptors alteration is present. This is an obvious chance about diagnosis and prognosis in these patients.
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