The Natural History of Inherited Retinal Dystrophy Due to Biallelic Mutations in the RPE65 Gene

International audiencePURPOSE:To delineate the natural history of visual parameters over time in individuals with biallelic RPE65 mutation-associated inherited retinal dystrophy (IRD); describe the range of causative mutations; determine potential genotype/phenotype relationships; and describe the variety of clinical diagnoses.DESIGN:Global, multicenter, retrospective chart review.METHODS:Study Population: Seventy individuals with biallelic RPE65 mutation-associated IRD.PROCEDURES:Data were extracted from patient charts.MEASUREMENTS:Visual acuity (VA), Goldmann visual field (GVF), optical coherence tomography, color vision testing, light sensitivity testing, and electroretinograms (retinal imaging and fundus photography were collected and analyzed when available).RESULTS:VA decreased with age in a nonlinear, positive-acceleration relationship (P < .001). GVF decreased with age (P < .0001 for both V4e and III4e), with faster GVF decrease for III4e stimulus vs V4e (P = .0114, left eye; P = .0076, right eye). On average, a 1-year increase in age decreased III4e GVF by ∼25 sum total degrees in each eye while V4e GVF decreased by ∼37 sum total degrees in each eye, although individual variability was observed. A total of 78 clinical diagnoses and 56 unique RPE65 mutations were recorded, without discernible RPE65 mutation genotype/phenotype relationships.CONCLUSIONS:The number of clinical diagnoses and lack of a consistent RPE65 mutation-to-phenotype correlation underscore the need for genetic testing. Significant relationships between age and worsening VA and GVF highlight the progressive loss of functional retina over time. These data may have implications for optimal timing of treatment for IRD attributable to biallelic RPE65 mutations

A linearization account of either … or constructions

To account for the linear freedom of either in disjunction constructions, I expand upon the focus-based account of den Dikken (2006).Word order constraints, in contrast to movement rules or base-generation constraints, provide the mechanism for explaining the distributional data. I argue that all positional variability exhibited by either ultimately derives from a licensing construction that enables either to be shuffled about disjunct-internally, yet simultaneously prevents either from entering into linear precedence relations with disjunct-external constituents. Restrictions on the surface realization of either result from a linear precedence rule ordering either before the contrastive focus, language particular constraints on word order, and general constraints on coordinate ellipsis. Overall, this analysis presents an account of either . . . or constructions that introduces only a single linear precedence rule and a licensing construction for combining either with disjunctions to account for the data, relying on independently-motivated constraints to carry the rest of the analytical burden

On the superficiality of Welsh agreement

A notable feature of Welsh is a number of agreement phenomena, all of which only occur with pronouns. Finite verbs agree with a following pronominal subject, prepositions agree with a following pronominal complement, and a particle which introduces non-finite clauses agrees with a following pronominal subject. Similarly, nouns have a preceding clitic agreeing with a following pronominal possessor, non-finite verbs have a preceding clitic agreeing with a following pronominal object, and what looks like the non-finite form of bod "be", which introduces certain subordinate clauses, has a preceding clitic agreeing with a following pronominal subject. There seems to be a single phenomenon here. Approaches that involve an abstract level face problems and there is no evidence that the phenomenon involves an abstract level. It seems quite plausible to suggest that superficial linear order is crucial, and this idea can be implemented in a straightforward way within linearization-based Head-driven Phrase Structure Grammar (HPSG). The properties of agreement also entail that unexpressed noun phrases of various kinds must be represented in the superficial constituent structure and not just at some abstract level, contrary to the view of some frameworks. © 2009 Springer Science+Business Media B.V