Retinal Degeneration in Hereditary Ataxia

Abstract

Deterioration of vision is a not infrequent occurrence in cases of hereditary ataxia. Like the ataxic symptoms it is progressive and may become severe. According to the literature the deterioration of vision has been ascribed to optic atrophy in the majority of cases and only in a few instances are retinal changes or cataract described. It is obvious, however, that the actual findings have often been very slight and that in some cases the ophthalmoscopical picture has been recorded as normal despite a strong reduction in visual acuity (Bell and Carmichael, 1939; van Bogaert, 1948). The present study gives an account of five cases of hereditary ataxia associated with serious loss of vision. The patients have been subjected to careful examination including electro-2SLux retinography(E.R.G.) _ in four of the cases. _ ___ This examination has revealed new facts that elucidate the 1O Lux problems associated A with the causation and progression of impairment of vision in this disorder.

Spinocerebellar Ataxia Type 7 (SCA7) Shows a Cone–Rod Dystrophy Phenotype

“…If full ®eld ERGs were performed, the results could be normal or abnormal. If rod and cone selective stimuli were used in the ERG studies, abnormalities tended to be more prominent in cone-mediated responses or in both cone and rod signals (Bjo Èrk 1956;Jampel 1961;de Jong et al, 1980;Hamilton et al, 1990;Neetens et al, 1990;. It can be assumed that many of these families had SCA7.…”

“…Ataxin-7 shares a short and functional motif homologous to the phosphate-binding site of arrestins (Mushegian et al, 2000). It localizes to the nucleus and/or the cytoplasm depending on the cell population and is widely expressed in human tissues, including the retina Kaytor et al, 1999;Cancel et al, 2000;Lindenberg et al, 2000;Einum et al, 2001). It has been postulated that the expanded allele induces a cytotoxic gain of function in the protein (Mauger et al, 1999).…”

Further delineation of spondylometaphyseal dysplasia with cone‐rod dystrophy

“…There are 13 known syndromal CRD types besides SMD-CRD. These can be metabolic disorders (thiamine-responsive megaloblastic anemia; mitochondriopathy caused by mutation T8993G [Porto et al, 2001]; infantile Refsum disease), ciliopathies (Alstrom and Bardet-Biedl syndromes), collagenopathy (Alport disease), polyglutamin toxicity disorder (spinocerebellar ataxia type 7), neurofibromatosis type 1 [Kylstra and Aylsworth, 1993], hypotrichosis with juvenile macular dystrophy caused by mutations in P-cadherin [Wagner, 1935] and disorders with unknown etiology such as CRD and amelogenesis imperfecta [Jalili and Smith, 1988], CRD and Pierre Marie ataxia [Bjork et al, 1956], CRD and trichomegaly [Jalili, 1989] and CRD with cleft lip [Ausems et al, 1996].…”

Heredoataxia (Spinocerebellar Degeneration), ERG Alterations, Temporal Aspects

“…The ocular abnormalities found in asso ciation with heredoataxia syndromes are chiefly ophthalmoplegia, atrophy of the op tic disk, and tapetoretinal degeneration [4,7,8], It is quite likely that the cases with optic atrophy are in fact pigmentary degen eration 'sine pigmento' [3,9,17]. Only the The results of our study reveal clear-cut impairment of ERG; 'implicit time' and am plitude in patients with heredoataxia despite minor or no ophthalmoscopic changes.…”