Mutation screening of 299 Spanish families with retinal dystrophies by Leber congenital amaurosis genotyping microarray.
OBJECTIVE
Leber Congenital Amaurosis (LCA) is one of the most severe inherited retinal dystrophies with the earliest age of onset. This study was a mutational analysis of eight genes (AIPL1, CRB1, CRX, GUCY2D, RPE65, RPGRIP1, MERTK, and LRAT) in 299 unrelated Spanish families, containing 42 patients with initial diagnosis of LCA: 107 with early-onset autosomal recessive retinitis pigmentosa (ARRP; onset <10 years of age) and 150 with non-early-onset ARRP (onset, >10 years of age).


METHODS
Samples were studied by using a genotyping microarray (Asper Biotech, Ltd., Tartu, Estonia) followed by a family study in cases with potential digenism/triallelism.


RESULTS
The frequencies of alleles carrying disease-causing mutations found in the authors'cohort using the chip were 23.8% (20/84) for LCA with 13 families carrying mutations, 6.1% (13/214) for early-onset ARRP with 12 families carrying mutations, and 4.3% (13/300) for non-early-onset ARRP with 12 families carrying mutations. CRB1 was the most frequently found mutated gene in affected Spanish families. Five families with anticipated digenism or triallelism were further studied in depth. Digenism could be discarded in all these cases; however, triallelism could not be ruled out.


CONCLUSIONS
CRB1 is the main gene responsible for LCA in the Spanish population. Sequence changes p.Asp1114Gly (RPGRIP1), p.Pro701Ser (GUCY2D), and p.Tyr134Phe (AIPL1) were found at similar frequencies in patients and control subjects. The authors therefore suggest that these changes be considered as polymorphism or modifier alleles, rather than as disease-causing mutations. The LCA microarray is a quick and reasonably low-cost first step in the molecular diagnosis of LCA. The diagnosis should be completed by conventional laboratory analysis as a second step. This stepwise proceeding permits detection of novel disease-causing mutations and identification of cases involving potential digenism/triallelism. Previous accurate ophthalmic diagnosis was found to be indispensable.
Department of Genetics, Fundacion Jimenez Diaz-CIBERER, Madrid, Spain.
Elena
E
Vallespin
Diego
D
Cantalapiedra
Rosa
R
Riveiro-Alvarez
Robert
R
Wilke
Jana
J
Aguirre-Lamban
Almudena
A
Avila-Fernandez
Miguel Angel
MA
Lopez-Martinez
Ascension
A
Gimenez
Maria Jose
MJ
Trujillo-Tiebas
Carmen
C
Ramos
Carmen
C
Ayuso
D048868:Adaptor Proteins, Signal Transducing; D000483:Alleles; D001766:Blindness / Q000151:congenital / Q000208:ethnology / Q000235:genetics*; D002352:Carrier Proteins / Q000235:genetics; D002648:Child; D003598:Cytoskeletal Proteins; D004252:DNA Mutational Analysis; D005136:Eye Proteins / Q000235:genetics*; D005260:Female; D020869:Gene Expression Profiling; D005820:Genetic Testing; D005838:Genotype; D006162:Guanylate Cyclase / Q000235:genetics; D018398:Homeodomain Proteins / Q000235:genetics; D006801:Humans; D008297:Male; D008565:Membrane Proteins / Q000235:genetics; D009154:Mutation; D009419:Nerve Tissue Proteins / Q000235:genetics; D020411:Oligonucleotide Array Sequence Analysis; D010375:Pedigree; D011506:Proteins / Q000235:genetics; D011956:Receptors, Cell Surface / Q000235:genetics; D012174:Retinitis Pigmentosa / Q000151:congenital / Q000208:ethnology / Q000235:genetics*; D013030:Spain / Q000453:epidemiology; D015534:Trans-Activators / Q000235:genetics; D019745:cis-trans-Isomerases; D000099178:Retinoid Isomerohydrolase
D048868:Adaptor Proteins, Signal Transducing; D002352:Carrier Proteins; D003598:Cytoskeletal Proteins; D005136:Eye Proteins; D006162:Guanylate Cyclase; D018398:Homeodomain Proteins; D008565:Membrane Proteins; D009419:Nerve Tissue Proteins; D011506:Proteins; D011956:Receptors, Cell Surface; D015534:Trans-Activators; D019745:cis-trans-Isomerases; D000099178:Retinoid Isomerohydrolase; C403625:AIPL1 protein, human; C448939:CRB1 protein, human; C415903:RPGRIP1 protein, human; C109288:cone rod homeobox protein; C110715:guanylate cyclase 1