Clinical and molecular genetics of Leber's congenital amaurosis: a multicenter study of Italian patients.
OBJECTIVE
To identify the molecular basis of Leber's congenital amaurosis (LCA) in a cohort of Italian patients and to perform genotype-phenotype analysis.


METHODS
DNA samples from 95 patients with LCA were analyzed by using a microarray chip containing disease-associated sequence variants in eight LCA genes. In addition, all patients in whom no mutations were identified by microarray were subjected to sequence analysis of the CEP290 gene. Patients with mutations identified underwent a detailed ophthalmic evaluation.


RESULTS
Disease-causing mutations were identified in 28% of patients, and twelve novel variants were identified. Mutations occurred more frequently in the RPE65 (8.4%), CRB1 (7.4%), and GUCY2D (5.2%) genes. Mutations in CEP290 were found in only 4.2% of the patients analyzed. Clinical assessment of patients carrying RPE65 or CRB1 mutations revealed the presence of retained visual capabilities in the first decade of life. RPE65 mutations were almost always associated with normal macular thickness, as assessed by optical coherence tomography (OCT), whereas CRB1 mutations were associated with reduced retinal thickness and a coarsely laminated retina. Fundus autofluorescence was mostly observed in patients with RPE65 and GUCY2D mutations and was not elicitable in patients carrying CRB1.


CONCLUSIONS
RPE65 gene mutations represented a significant cause of LCA in the Italian population, whereas GUCY2D and CEP290 mutations had a lower frequency than that found in other reports. This finding suggests that the genetic epidemiology of LCA in Italy is different from that reported in the United States and in northern European countries. Autofluorescence in patients with RPE65 mutations was more frequently associated with preserved retinal thickness, which suggests that these mutations are not associated with progression of retinal degeneration. Therefore, normal retinal thickness (identified with OCT) and fundus autofluorescence may be the means with which to identify patients with LCA who carry RPE65 mutations, which are expected to be a potential gene therapy target in the near future.
Simonelli
Francesca
F
Department of Ophthalmology, Second University of Naples, Naples, Italy. franctes@tin.it
Ziviello
Carmela
C
Testa
Francesco
F
Rossi
Settimio
S
Fazzi
Elisa
E
Bianchi
Paolo Emilio
PE
Fossarello
Maurizio
M
Signorini
Sabrina
S
Bertone
Chiara
C
Galantuomo
Silvana
S
Brancati
Francesco
F
Valente
Enza Maria
EM
Ciccodicola
Alfredo
A
Rinaldi
Ernesto
E
Auricchio
Alberto
A
Banfi
Sandro
S
D000951:Antigens, Neoplasm / Q000235:genetics*; D001766:Blindness / Q000453:epidemiology* / Q000235:genetics*; D002352:Carrier Proteins / Q000235:genetics*; D018797:Cell Cycle Proteins; D003598:Cytoskeletal Proteins; D004252:DNA Mutational Analysis; D005136:Eye Proteins / Q000235:genetics*; D020869:Gene Expression Profiling; D005838:Genotype; D006162:Guanylate Cyclase / Q000235:genetics*; D006801:Humans; D007558:Italy / Q000453:epidemiology; D008565:Membrane Proteins / Q000235:genetics; D008967:Molecular Biology; D017720:Molecular Epidemiology; D009154:Mutation; D009363:Neoplasm Proteins / Q000235:genetics*; D009419:Nerve Tissue Proteins / Q000235:genetics; D020411:Oligonucleotide Array Sequence Analysis; D010641:Phenotype; D011956:Receptors, Cell Surface / Q000235:genetics*; D012162:Retinal Degeneration / Q000453:epidemiology / Q000235:genetics; D041623:Tomography, Optical Coherence; D019745:cis-trans-Isomerases; D000099178:Retinoid Isomerohydrolase
D000951:Antigens, Neoplasm; D002352:Carrier Proteins; D018797:Cell Cycle Proteins; D003598:Cytoskeletal Proteins; D005136:Eye Proteins; D006162:Guanylate Cyclase; D008565:Membrane Proteins; D009363:Neoplasm Proteins; D009419:Nerve Tissue Proteins; D011956:Receptors, Cell Surface; D019745:cis-trans-Isomerases; D000099178:Retinoid Isomerohydrolase; C448939:CRB1 protein, human; C493903:Cep290 protein, human; C110715:guanylate cyclase 1