Are microarrays useful in the screening of ABCA4 mutations in Italian patients affected by macular degenerations?
BACKGROUND
Recessive Stargardt disease is due to mutation in the retina-specific ABC transporter gene. Established strategies for molecular characterization of this gene include direct detection by a microarray interrogating approximately 500 DNA variations and a scanning denaturing HPLC methodology.


METHODS
Because 11 mutations were recorded to account for approximately 50% of molecular defects in the Italian population, we evaluated an alternative open microchip-based assay for a fast and simplified level 1 screening for these mutations.


RESULTS
This approach allowed the characterization of both mutated alleles in 4% and one mutated allele in 43% of cases when applied to a cohort of 47 Stargardt patients. In the same patients, further investigation by denaturing HPLC for complete characterization identified both mutated allele in 51% and one mutated allele in 19% of cases, allowing the detection of 38 different mutations, five of which had never been described. Notably, new mutations account for a high proportion (13%) of molecular defects in our patient cohort.


CONCLUSIONS
The findings raises the question about the choice of the optimal diagnostic strategy for complete genotyping of the ABCA4 gene, as new mutations could not be identified by any direct detection technology, irrespective of the total number of variations screened.
Stenirri
Stefania
S
Genomic Unit for the Diagnosis of Human Pathologies, San Raffaele Scientific Institute, Milan, Italy.
Alaimo
Georgia
G
Manitto
Maria Pia
MP
Brancato
Rosario
R
Ferrari
Maurizio
M
Cremonesi
Laura
L
D018528:ATP-Binding Cassette Transporters / Q000235:genetics*; D002851:Chromatography, High Pressure Liquid; D006801:Humans; D007558:Italy; D008268:Macular Degeneration / Q000235:genetics* / Q000378:metabolism; D009154:Mutation; D020411:Oligonucleotide Array Sequence Analysis
C056475:ABCA4 protein, human; D018528:ATP-Binding Cassette Transporters