ABCMdb

PMID: 21330655

Aguirre-Lamban J, Gonzalez-Aguilera JJ, Riveiro-Alvarez R, Cantalapiedra D, Avila-Fernandez A, Villaverde-Montero C, Corton M, Blanco-Kelly F, Garcia-Sandoval B, Ayuso C
Further associations between mutations and polymorphisms in the ABCA4 gene: clinical implication of allelic variants and their role as protector/risk factors.
Invest Ophthalmol Vis Sci. 2011 Aug 5;52(9):6206-12. Print 2011 Aug., [PubMed]

Sentences

No. Mutations Sentence Comment

9 ABCA4 p.Asn1868Ile ABCA4 p.Arg943Gln The use of statistical methods showed that the frequency of the majority of polymorphisms was similar in patients and controls, except for the IVS10ϩ5delG, p.Asn1868Ile, IVS48ϩ21CϾT, and p.Arg943Gln polymorphisms. Login to comment 10 ABCA4 p.Gly1961Glu ABCA4 p.Arg602Trp ABCA4 p.Arg943Gln In addition, IVS48ϩ21CϾT and p.Arg943Gln were found to be in linkage disequilibrium with the p.Gly1961Glu and p.Arg602Trp mutations, respectively. Login to comment 12 ABCA4 p.Asn1868Ile ABCA4 p.His423Arg Although the high allelic heterogeneity in ABCA4 and the wide spectrum of many common and rare polymorphisms complicate the interpretation of clinical relevance, polymorphisms were identified that may act as risk factors (p.Asn1868Ile) and others that may act as protection factors (p.His423Arg and IVS10ϩ5 delG). Login to comment 68 ABCA4 p.Gly1961Glu Interestingly, only the p.Gly1961Glu substitution was identified in both patient and control groups. Login to comment 69 ABCA4 p.Gly1961Glu Interestingly, only the p.Gly1961Glu substitution was identified in both patient and control groups. Login to comment 72 ABCA4 p.Gly1961Glu ABCA4 p.Arg602Trp ABCA4 p.Leu2060Arg ABCA4 p.Arg1129Leu Mutations and Polymorphisms in the Patient Cohort ABCA4 mutation screening demonstrated that the most frequent (Ͼ5%) disease-associated alleles were the following: p.Arg1129Leu, p.Gly1961Glu, p.Arg602Trp, c.3211insGT, and p.Leu2060Arg (Table 1; Fig. 1). Login to comment 73 ABCA4 p.Gly1961Glu ABCA4 p.Arg602Trp ABCA4 p.Leu2060Arg ABCA4 p.Arg1129Leu Mutations and Polymorphisms in the Patient Cohort ABCA4 mutation screening demonstrated that the most frequent (b0e;5%) disease-associated alleles were the following: p.Arg1129Leu, p.Gly1961Glu, p.Arg602Trp, c.3211insGT, and p.Leu2060Arg (Table 1; Fig. 1). Login to comment 74 ABCA4 p.Arg1129Leu ABCA4 p.Arg1129Leu p.Arg1129Leu The most frequent mutation in the group of patients was p.Arg1129Leu, detected in 34 patients and with a frequency of 26.6% (Table 1). Login to comment 75 ABCA4 p.His423Arg ABCA4 p.His423Arg ABCA4 p.Arg1129Leu ABCA4 p.Arg1129Leu ABCA4 p.Arg1129Leu ABCA4 p.Arg1129Leu Once this variant was compared to cis-acting polymorphisms, statistical analyses demonstrated significant differences among p.Arg1129Leu and the p.His423Arg and IVS33ϩ48CϾT variants: 94.1% of the p.Arg1129Leu patients also had the p.His423Arg change (P ϭ Ͻ0.001), and 100% of them also carried the IVS33ϩ48CϾT polymorphism (P ϭ 0.003) (Table 3). Login to comment 76 ABCA4 p.Asn1868Ile ABCA4 p.His423Arg ABCA4 p.His423Arg ABCA4 p.Arg1129Leu ABCA4 p.Arg1129Leu ABCA4 p.Arg1129Leu In contrast, the p.Pro1401Pro, p.Asn1868Ile, p.Leu1894Leu, and p.Leu1938Leu variants were less frequently detected among the p.Arg1129Leu patients (Table 3). Login to comment 77 ABCA4 p.Asn1868Ile ABCA4 p.His423Arg ABCA4 p.Arg1129Leu ABCA4 p.Arg1129Leu Despite this, p.His423Arg, IVS33ϩ48CϾT, p.Pro1401Pro, p.Leu1894Leu, and p.Leu1938Leu polymorphisms were detected in similar frequencies between p.Arg1129Leu patients and the control population, since no significant differences existed (P ϭ 0.108, 0.542, 0.605, 0.130, and 0.394 respectively). Login to comment 78 ABCA4 p.Gly1961Glu ABCA4 p.Gly1961Glu ABCA4 p.His423Arg ABCA4 p.Arg1129Leu p.Gly1961Glu The p.Gly1961Glu mutation was the second most frequent missense variant, with a frequency of 14.1% (Table 1). Login to comment 79 ABCA4 p.Gly1961Glu ABCA4 p.Gly1961Glu p.Gly1961Glu was found in association with the following polymorphisms: p.Leu1894Leu in 100% of the patients (P Ͻ 0.001), p.Pro1948Pro in 94.4% (P Ͻ 0.001), p.Leu1938Leu in 89.9% (P Ͻ 0.001), p.Asp2095Asp in 83.3% (P Ͻ 0.001, and IVS10ϩ5delG in 55.6% of the cases (P ϭ 0.005). Login to comment 80 ABCA4 p.Gly1961Glu ABCA4 p.Gly1961Glu Similarly, IVS48ϩ21CϾT was found to exist in association with p.Gly1961Glu in 72.2% of 18 individuals (P Ͻ 0.001) and was not found in the remaining patients (Table 3). Login to comment 81 ABCA4 p.Gly1961Glu Similarly, IVS48af9;21Cb0e;T was found to exist in association with p.Gly1961Glu in 72.2% of 18 individuals (P b0d; 0.001) and was not found in the remaining patients (Table 3). Login to comment 82 ABCA4 p.Gly1961Glu However, two polymorphic variants were found to be less frequently associated with the p.Gly1961Glu mutation in TABLE 1. Login to comment 83 ABCA4 p.Gly1961Glu ABCA4 p.Gly1961Glu ABCA4 p.Gly1961Glu ABCA4 p.Arg602Trp ABCA4 p.Leu2060Arg ABCA4 p.Arg1129Leu Most Frequent ABCA4 Disease-Associated Alleles Identified in the Patient Cohort Exon Nucleotide Change Aminoacid Change Patients n (%) Allele Frequency n (%) Controls n (%) Allele Frequency n (%) P 23 c.3386GϾT p.Arg1129Leu 34 (26.6) 38 (14.8) 0 (0.0) 0 (0.0) 0.000 42 c.5882GϾA p.Gly1961Glu 18 (14.1) 18 (7.0) 1 (1.2) 1 (0.6) 0.001 13 c.1804CϾT p.Arg602Trp 8 (6.3) 9 (3.5) 0 (0.0) 0 (0.0) 0.020 22 c.3211insGT Frameshift 7 (5.5) 7 (2.7) 0 (0.0) 0 (0.0) 0.029 45 c.6179TϾG p.Leu2060Arg 7 (5.5) 7 (2.7) 0 (0.0) 0 (0.0) 0.029 Note that only the p.Gly1961Glu substitution was identified in both patients and control groups. Login to comment 84 ABCA4 p.Gly1961Glu ABCA4 p.Gly1961Glu ABCA4 p.Arg602Trp ABCA4 p.Leu2060Arg ABCA4 p.Arg1129Leu Most Frequent ABCA4 Disease-Associated Alleles Identified in the Patient Cohort Exon Nucleotide Change Aminoacid Change Patients n (%) Allele Frequency n (%) Controls n (%) Allele Frequency n (%) P 23 c.3386Gb0e;T p.Arg1129Leu 34 (26.6) 38 (14.8) 0 (0.0) 0 (0.0) 0.000 42 c.5882Gb0e;A p.Gly1961Glu 18 (14.1) 18 (7.0) 1 (1.2) 1 (0.6) 0.001 13 c.1804Cb0e;T p.Arg602Trp 8 (6.3) 9 (3.5) 0 (0.0) 0 (0.0) 0.020 22 c.3211insGT Frameshift 7 (5.5) 7 (2.7) 0 (0.0) 0 (0.0) 0.029 45 c.6179Tb0e;G p.Leu2060Arg 7 (5.5) 7 (2.7) 0 (0.0) 0 (0.0) 0.029 Note that only the p.Gly1961Glu substitution was identified in both patients and control groups. Login to comment 85 ABCA4 p.Arg212His ABCA4 p.Asn1868Ile ABCA4 p.Pro1948Leu ABCA4 p.Arg943Gln ABCA4 p.His423Arg ABCA4 p.Ser2255Ile Most Frequent ABCA4 Polymorphisms Found in Patients and Controls Exon Nucleotide Change Amino Acid Change Patients n (%) Allele Frequency n (%) Controls n (%) Allele Frequency n (%) P - IVS48؉21C>T SPLICE 13 (10.2) 13 (5.1) 0 (0.0) 0 (0.0) 0.003 - IVS10؉5 delG SPLICE 36 (28.1) 40 (15.6) 39 (46.4) 43 (25.6) 0.006 40 c.5603A>T p.Asn1868Ile 27 (21.1) 30 (11.7) 9 (10,7) 9 (5.3) 0.049 19 c.2828GϾA p.Arg943Gln 13 (10.2) 15 (5.8) 3 (3.6) 3 (1.8) 0.076 45 c.6249CϾT p.Ile2083Ile 14 (10.9) 15 (5.8) 16 (19.0) 18 (10.7) 0.098 49 c.6764GϾT p.Ser2255Ile 13 (10.2) 13 (5.1) 15 (17.9) 16 (9.5) 0.105 10 c.1268AϾG p.His423Arg 68 (53.1) 84 (32.8) 54 (64.3) 60 (35.7) 0.108 40 c.5682GϾC p.Leu1894Leu 70 (54.7) 90 (35.1) 37 (44.0) 41 (24.4) 0.130 42 c.5843CAϾTG p.Pro1948Leu 13 (10.2) 13 (5.1) 14 (16.7) 15 (8.9) 0.164 8 c.981CϾT p.Pro327Pro 2 (1.6) 2 (0.8) 0 (0.0) 0 (0.0) 0.250 6 c.635GϾA p.Arg212His 8 (6.3) 11 (4.3) 8 (9.5) 8 (4.7) 0.377 41 c.5814AϾG p.Leu1938Leu 40 (31.3) 48 (18.7) 31 (36.9) 35 (20.8) 0.394 44 c.6069CϾT p.Ile2023Ile 17 (13.3) 17 (6.6) 14 (16.7) 15 (8.9) 0.495 IVS33ϩ48CϾT SPLICE 109 (85.2) 170 (66.4) 74 (88.1) 93 (55.3) 0.542 28 c.4203CϾA/T p.Pro1401Pro 10 (7.8) 10 (3.9) 5 (6.0) 5 (2.9) 0.605 10 c.1269CϾT p.His423His 8 (6.3) 8 (3.1) 4 (4.8) 4 (2.4) 0.647 42 c.5844AϾG p.Pro1948Pro 36 (28.1) 42 (16.4) 23 (27.4) 25 (14.9) 0.906 46 c.6285TϾC p.Asp2095Asp 39 (30.5) 43 (16.8) 25 (29.8) 27 (16.1) 0.913 Variants revealing significant differences between both groups are shown in bold. Login to comment 86 ABCA4 p.Arg212His ABCA4 p.Asn1868Ile ABCA4 p.Asn1868Ile ABCA4 p.Pro1948Leu ABCA4 p.Arg943Gln ABCA4 p.His423Arg ABCA4 p.His423Arg ABCA4 p.Ser2255Ile the patient group: p.Asn1868Ile (P ϭ 0.013) and p.His423Arg (P ϭ 0 0.023) (Table 3). Login to comment 87 ABCA4 p.Gly1961Glu ABCA4 p.Asn1868Ile ABCA4 p.Asn1868Ile ABCA4 p.His423Arg The p.Asn1868Ile variant was found in higher proportion in patients than in control individuals (P ϭ 0.049) (Table 2) and was not present in the 82% of the carrier patients of the p.Gly1961Glu mutation (P ϭ 0.013) (Table 3). Login to comment 88 ABCA4 p.Gly1961Glu ABCA4 p.Arg602Trp ABCA4 p.Arg602Trp ABCA4 p.Asn1868Ile p.Arg602Trp The p.Arg602Trp mutation was found to be the third most prevalent missense variant, with a frequency of 6.3% (Table 1). Login to comment 89 ABCA4 p.Arg602Trp ABCA4 p.Arg602Trp ABCA4 p.Arg943Gln Using the Pearson`s ␹;2 test, a significant association was detected between this alteration and the p.Arg943Gln polymorphism (P Ͻ 0.001), since 62.5% of the patients showed both sequence variants. Login to comment 90 ABCA4 p.Arg943Gln ABCA4 p.Arg943Gln Moreover, p.Arg943Gln was found in higher proportion in patients than in control individuals (P ϭ 0.076) (Table 2; Fig. 1). Login to comment 91 ABCA4 p.Arg602Trp ABCA4 p.Arg943Gln In contrast with this, the p.Leu1938Leu variant was less frequently detected among patients with p.Arg602Trp and had a frequency of 0% (P ϭ 0.05) (Table 3). Login to comment 92 ABCA4 p.Arg602Trp In contrast with this, the p.Leu1938Leu variant was less frequently detected among patients with p.Arg602Trp and had a frequency of 0% (P afd; 0.05) (Table 3). Login to comment 93 ABCA4 p.Asn1868Ile ABCA4 p.His423Arg This variant was significantly associated with p.His423Arg (P ϭ 0.014), p.Asn1868Ile (P Ͻ 0.001), and p.Leu1894Leu (P ϭ 0.016), as 100% of the patients carried both the mutation and these polymorphisms (Table 3). Login to comment 94 ABCA4 p.Arg602Trp ABCA4 p.Asn1868Ile ABCA4 p.Asn1868Ile ABCA4 p.Pro1948Leu ABCA4 p.His423Arg ABCA4 p.Arg1129Leu ABCA4 p.Ser2255Ile p.Arg212H is p.Pro327Pro p.H is423Arg p.H is423H is IVS10+5delG p.Arg602Trp p.Arg943G ln c.3211insG T p.Arg1129Leu p.Pro1401Pro IVS33+48C >Tp.Leu1894Leu p-Leu1938Leu p.Pro1948Leu p.Pro1948Pro p.G ly1961G lup.Leu2060Argp.Asp2095Asp IVS48+21C >T - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - p.Asn1868Ile p.Ile2023Ile p.Ile2083Ile p.Ser2255Ile PATIENTSCONTROLS FIGURE 1. Login to comment 96 ABCA4 p.Leu2060Arg ABCA4 p.Leu2060Arg p.Leu2060Arg The fifth most frequently detected mutation was p.Leu2060Arg (5.5%) (Table 1). Login to comment 97 ABCA4 p.Pro1948Leu This change was found to be associated with p.Leu1894Leu (P ϭ 0.016), p.Leu1938Leu, and p.Pro1948Leu polymorphic variants in 100% of the cases (P Ͻ 0.001). Login to comment 98 ABCA4 p.His423Arg ABCA4 p.Leu2060Arg However, p.His423Arg was less frequently detected among patients harboring p.Leu2060Arg, since the frequency of this occurrence was 14.3% (P ϭ 0.05) (Table 3). Login to comment 100 ABCA4 p.Asn1868Ile Except for the IVS10ϩ5delG, p.Asn1868Ile, and IVS48ϩ21CϾT polymorphisms, the remaining polymorphic variants whose frequency was Ͼ5% failed to show any significant differences between patients and control individuals (Table 2; Fig. 1). Login to comment 101 ABCA4 p.His423Arg Polymorphisms and Risk Carriers of the p.His423Arg and IVS10ϩ5 delG variants have a diminished risk of disease compared to normal homozygous variant (OR: AGϩGG ϭ 0.46; 95% CI, 0.25-0.86; P ϭ 0.015; and OR: N/D ϩ DD ϭ 0.45; 95% CI, 0.25-0.80; P ϭ 0.007, respectively; Table 4). Login to comment 102 ABCA4 p.Asn1868Ile Carriers of the T variant (homozygous and heterozygous) of p.Asn1868Ile are at more than double the risk of developing the disease than normal homozygous variant (OR: ATϩTT ϭ 2.23; 95% CI, 1.01-5.01; P ϭ 0.05; Table 4). Login to comment 108 ABCA4 p.His423Arg The p.His423Arg and IVS10ϩ5 delG polymorphisms show a protective effect of the disease (OR: AGϩGG ϭ 0.46; 95% CI, 0.25-0.86; P ϭ 0.015, and OR: N/D ϩ DD ϭ 0.45; 95% CI, TABLE 3. Login to comment 109 ABCA4 p.Gly1961Glu ABCA4 p.Arg602Trp ABCA4 p.Asn1868Ile ABCA4 p.Asn1868Ile ABCA4 p.Pro1948Leu ABCA4 p.Arg943Gln ABCA4 p.His423Arg ABCA4 p.His423Arg ABCA4 p.His423Arg ABCA4 p.His423Arg ABCA4 p.Leu2060Arg ABCA4 p.Arg1129Leu ABCA4 p.Ser2255Ile Association between the Most Frequent ABCA4 Polymorphisms and Mutations Patients Variants Frequency P Status Predicted Effect Mutation, n (%) p.Arg1129Leu 34 (26.6) Present polymorphisms p.His423Arg 94.1% 0.000 Associated Risk IVS33؉48C>T 100% 0.011 Associated Risk IVS10ϩ5delG 20.6% 0.049 Associated Protector p.Leu1938Leu 17.6% 0.033 Associated Protector p.Ser2255Ile 2.9% 0.054 Associated Protector Mutation, n (%) p.Gly1961Glu 18 (14.1) Present polymorphisms p.Pro1948Pro 94.7% 0.000 Associated Risk p.Leu1938Leu 89.5% 0.000 Associated Risk p.Asp2095Asp 78.9% 0.000 Associated Risk IVS48؉21C>T 70.0% 0.000 Associated Risk IVS10؉5delG 57.9% 0.008 Associated Risk p.His423Arg 31.6% 0.016 Associated Protector p.Asn1868Ile 18.7% 0.039 Associated Protector Mutation, n (%) p.Arg602Trp 8 (6.3%) Present polymorphisms p.Arg943Gln 62.5% 0.000 Associated Risk p.Pro1401Pro 25% 0.044 Associated Protector p.Leu1938Leu 0% 0.041 Associated Protector Mutation, n (%) c.3211insGT 7 (5.5%) Present polymorphisms p.His423Arg 100% 0.021 Associated Risk p.Asn1868Ile 100% 0.000 Associated Risk IVS10ϩ5delG 0% 0.047 Associated Protector Mutation, n (%) p.Leu2060Arg 7 (5.5%) Present polymorphisms p.Leu1938Leu 100% 0.000 Associated Risk p.Pro1948Leu 100% 0.000 Associated Risk p.His423Arg 14.3% 0.019 Associated Protector TABLE 4. Login to comment 110 ABCA4 p.Asn1868Ile ABCA4 p.His423Arg Polymorphisms and Risk of Stargardt Disease Polymorphism Genotype Cases (n ‫؍‬ 128) N Controls (n ‫؍‬ 84) N OR 95% CI P p.His423Arg AA 60 30 1 (reference) AGϩGG 68 54 0.464 0.250-0.863 0.015 IVS10ϩ5 delG Normal 92 45 1 (reference) N/DϩD/D 36 39 0.452 0.254-0.804 0.007 p.Asn1868Ile AA 101 75 1 (reference) ATϩTT 27 9 2.23 0.990-5.015 0.05 0.25-0.80; P ϭ 0.007, respectively). Login to comment 111 ABCA4 p.Asn1868Ile However, carriers of the variant sequences of the p.Asn1868Ile polymorphism exhibit a more than twofold risk of developing the disease than normal homozygous variant (OR: ATϩTT ϭ 2.23; 95% CI, 1.01-5.01; P ϭ 0.05; Table 4). Login to comment 112 ABCA4 p.Asn1868Ile Moreover, using a SIFT and a Polyphen prediction, the p.Asn1868Ile variant affected protein function. Login to comment 114 ABCA4 p.Gly1961Glu ABCA4 p.His423Arg ABCA4 p.Leu2060Arg This is the case of the p.His423Arg polymorphism and the p.Gly1961Glu and p.Leu2060Arg mutations (P ϭ 0.023; Table 3); in other cases, however, the same polymorphism was found in association with the pArg1129Leu and c.3211insGT mutations. Login to comment 115 ABCA4 p.Gly1961Glu ABCA4 p.Asn1868Ile Similarly, the p.Asn1868Ile polymorphism is negatively associated with both p.Gly1961Glu and pArg1129Leu mutations and in positive association with the c.3211insGT mutation (Table 3). Login to comment 116 ABCA4 p.Gly1961Glu ABCA4 p.Leu2060Arg ABCA4 p.Leu2060Arg As expected, no mutations were present in control samples, with the exception of p.Gly1961Glu (1.19%). Login to comment 117 ABCA4 p.Gly1961Glu ABCA4 p.Gly1961Glu ABCA4 p.Gly1961Glu ABCA4 p.Pro1948Leu It also was found in other control populations, although less frequently.15,17 The p.Gly1961Glu variant is the second most frequent mutation in our group of patients, although it has been described as the most frequent variant in European populations.14,15 We observe that the p.Gly1961Glu and IVS48ϩ21CϾT variants are in linkage disequilibrium, and the high frequency of the p.Gly1961Glu mutation in Europe may be the result of a founder effect. Login to comment 118 ABCA4 p.Gly1961Glu ABCA4 p.His423Arg ABCA4 p.Leu2060Arg The p.Gly1961Glu variant was found in 18 (out of 128) STGD patients and was considered a moderate allele.9 However, there is no linkage disequilibrium, since five out of 18 STGD patients did not carry the IVS48ϩ21CϾT polymorphism. Login to comment 119 ABCA4 p.Gly1961Glu One control individual was seen to carry the p.Gly1961Glu mutation but not the IVS48ϩ21CϾT polymorphism. Login to comment 120 ABCA4 p.Gly1961Glu ABCA4 p.Gly1961Glu ABCA4 p.Asn1868Ile ABCA4 p.Asn1868Ile ABCA4 p.His423Arg In a Danish population, both ABCA4 gene variants were found, though no possible association was analyzed.18 However, in a German population, 18 individuals were found to have the IVS48ϩ21CϾT polymorphism, of whom 17 had the p.Gly1961Glu mutation.15 As a contrast, p.Asn1868Ile and p.His423Arg are negatively associated with the p.Gly1961Glu mutation. Login to comment 121 ABCA4 p.Asn1868Ile ABCA4 p.His423Arg p.Asn1868Ile appears at a higher frequency in patients than in controls (P ϭ 0.049), although previous studies have found the variant to occur in higher, albeit insignificant, frequency among the control population.19 The IVS10ϩ5delG polymorphism was first described in 2001 by Webster et al.18 in a study on a Danish population. Login to comment 122 ABCA4 p.Gly1961Glu ABCA4 p.Asn1868Ile We found this polymorphism, IVS10ϩ5delG, to be associated with the p.Gly1961Glu mutation (P ϭ 0.005). Login to comment 124 ABCA4 p.Arg1129Leu The most frequent missense disease-associated allele was p.Arg1129Leu (26.6%), a mutation that does not appear in control individuals. Login to comment 125 ABCA4 p.His423Arg This mutation is hardly present at all in other populations.20 Appearing in 34 of 128 patients, the mutation is associated with both p.His423Arg and IVS33ϩ48CϾT polymorphisms (P ϭ 0.001 and 0.003, respectively). Login to comment 126 ABCA4 p.Asn1868Ile ABCA4 p.Arg1129Leu The p.Pro1401Pro, p.Asn1868Ile, p.Leu1894Leu, and p.Leu1938Leu polymorphisms, on the other hand, appeared less frequently among patients with the p.Arg1129Leu mutation. Login to comment 127 ABCA4 p.Asn1868Ile Except for p.Asn1868Ile, the remaining polymorphisms were found in a similar number of patients and normal control subjects (Table 2). Login to comment 128 ABCA4 p.His423Arg ABCA4 p.Arg1129Leu These facts suggest that the variants do not contribute to the disease and that the p.Arg1129Leu mutation is more recent than these polymorphisms. Login to comment 129 ABCA4 p.Gly1961Glu ABCA4 p.Arg602Trp ABCA4 p.Arg602Trp ABCA4 p.Asn1868Ile ABCA4 p.Asn1868Ile ABCA4 p.Pro1948Leu ABCA4 p.Arg943Gln ABCA4 p.Arg943Gln ABCA4 p.His423Arg ABCA4 p.His423Arg ABCA4 p.His423Arg ABCA4 p.His423Arg ABCA4 p.Leu2060Arg ABCA4 p.Arg1129Leu ABCA4 p.Ser2255Ile The p.Arg943Gln polymorphism is in linkage disequilibrium with the p.Arg602Trp mutation in Spanish STGD (P Ͻ 0.001, Table 3). Login to comment 130 ABCA4 p.Gly863Ala ABCA4 p.Asn1868Ile ABCA4 p.Arg943Gln ABCA4 p.His423Arg However, in other European studies the p.Arg943Gln variant was detected in linkage disequilibrium with the p.Gly863Ala mutation,18,19,20 and 21 but this mutation has a low frequency in our series of patients, and no association analysis was performed. Login to comment 131 ABCA4 p.Asn1868Ile ABCA4 p.Arg943Gln This change has been described showing diminished activity of the ABCA4 protein.11,22 However, using a SIFT and a Polyphen prediction, the p.Arg943Gln variant would not affect the protein function, so it is not clear how it affects the phenotype. Login to comment 132 ABCA4 p.Asn1868Ile Moreover, using a SIFT and a Polyphen prediction, the p.Asn1868Ile variant affected protein function. Login to comment 134 ABCA4 p.Gly1961Glu ABCA4 p.His423Arg ABCA4 p.Leu2060Arg This is the case of the p.His423Arg polymorphism and the p.Gly1961Glu and p.Leu2060Arg mutations (P afd; 0.023; Table 3); in other cases, however, the same polymorphism was found in association with the pArg1129Leu and c.3211insGT mutations. Login to comment 135 ABCA4 p.Gly1961Glu ABCA4 p.Asn1868Ile Similarly, the p.Asn1868Ile polymorphism is negatively associated with both p.Gly1961Glu and pArg1129Leu mutations and in positive association with the c.3211insGT mutation (Table 3). Login to comment 136 ABCA4 p.Gly1961Glu ABCA4 p.Arg602Trp ABCA4 p.Arg943Gln We found an association between p.Arg602Trp and p.Arg943Gln that has not been observed in other populations. Login to comment 137 ABCA4 p.Gly1961Glu ABCA4 p.Gly1961Glu ABCA4 p.Gly1961Glu ABCA4 p.Arg1129Leu On the other hand, we found the p.Arg1129Leu mutation in 26.6% (34 out of 128) of patients, and these results are in accordance with those of previous studies describing this mutation as the most frequent among Spanish people.23 These findings are in contrast with those obtained from other populations in which the frequency is low. Login to comment 138 ABCA4 p.Gly1961Glu The p.Gly1961Glu variant was found in 18 (out of 128) STGD patients and was considered a moderate allele.9 However, there is no linkage disequilibrium, since five out of 18 STGD patients did not carry the IVS48af9;21Cb0e;T polymorphism. Login to comment 139 ABCA4 p.Gly1961Glu ABCA4 p.Asn1868Ile Except for the IVS10ϩ5delG, p.Asn1868Ile and IVS48ϩ21CϾT polymorphisms, the remaining polymorphic variants showed no significant differences between patients and control individuals. Login to comment 140 ABCA4 p.Gly1961Glu ABCA4 p.Gly1961Glu ABCA4 p.Asn1868Ile ABCA4 p.His423Arg In a Danish population, both ABCA4 gene variants were found, though no possible association was analyzed.18 However, in a German population, 18 individuals were found to have the IVS48af9;21Cb0e;T polymorphism, of whom 17 had the p.Gly1961Glu mutation.15 As a contrast, p.Asn1868Ile and p.His423Arg are negatively associated with the p.Gly1961Glu mutation. Login to comment 141 ABCA4 p.Asn1868Ile p.Asn1868Ile appears at a higher frequency in patients than in controls (P afd; 0.049), although previous studies have found the variant to occur in higher, albeit insignificant, frequency among the control population.19 The IVS10af9;5delG polymorphism was first described in 2001 by Webster et al.18 in a study on a Danish population. Login to comment 142 ABCA4 p.Gly1961Glu We found this polymorphism, IVS10af9;5delG, to be associated with the p.Gly1961Glu mutation (P afd; 0.005). Login to comment 144 ABCA4 p.Asn1868Ile ABCA4 p.Arg1129Leu However, IVS10ϩ5delG and p.Asn1868Ile did not represent mutational hot spots. Login to comment 145 ABCA4 p.His423Arg This mutation is hardly present at all in other populations.20 Appearing in 34 of 128 patients, the mutation is associated with both p.His423Arg and IVS33af9;48Cb0e;T polymorphisms (P afd; 0.001 and 0.003, respectively). Login to comment 146 ABCA4 p.Asn1868Ile ABCA4 p.Arg1129Leu The p.Pro1401Pro, p.Asn1868Ile, p.Leu1894Leu, and p.Leu1938Leu polymorphisms, on the other hand, appeared less frequently among patients with the p.Arg1129Leu mutation. Login to comment 147 ABCA4 p.Asn1868Ile Except for p.Asn1868Ile, the remaining polymorphisms were found in a similar number of patients and normal control subjects (Table 2). Login to comment 148 ABCA4 p.Asn1868Ile ABCA4 p.His423Arg ABCA4 p.Arg1129Leu In conclusion, the p.His423Arg and IVS10ϩ5delG polymorphisms have a protective effect, whereas the p.Asn1868Ile polymorphism is a risk factor for disease. Login to comment 149 ABCA4 p.Arg602Trp ABCA4 p.Arg943Gln The p.Arg943Gln polymorphism is in linkage disequilibrium with the p.Arg602Trp mutation in Spanish STGD (P b0d; 0.001, Table 3). Login to comment 150 ABCA4 p.Gly863Ala ABCA4 p.Arg943Gln However, in other European studies the p.Arg943Gln variant was detected in linkage disequilibrium with the p.Gly863Ala mutation,18,19,20 and 21 but this mutation has a low frequency in our series of patients, and no association analysis was performed. Login to comment 151 ABCA4 p.Arg943Gln This change has been described showing diminished activity of the ABCA4 protein.11,22 However, using a SIFT and a Polyphen prediction, the p.Arg943Gln variant would not affect the protein function, so it is not clear how it affects the phenotype. Login to comment 156 ABCA4 p.Arg602Trp ABCA4 p.Arg943Gln We found an association between p.Arg602Trp and p.Arg943Gln that has not been observed in other populations. Login to comment 157 ABCA4 p.Arg1129Leu On the other hand, we found the p.Arg1129Leu mutation in 26.6% (34 out of 128) of patients, and these results are in accordance with those of previous studies describing this mutation as the most frequent among Spanish people.23 These findings are in contrast with those obtained from other populations in which the frequency is low. Login to comment 159 ABCA4 p.Asn1868Ile Except for the IVS10af9;5delG, p.Asn1868Ile and IVS48af9;21Cb0e;T polymorphisms, the remaining polymorphic variants showed no significant differences between patients and control individuals. Login to comment 164 ABCA4 p.Asn1868Ile However, IVS10af9;5delG and p.Asn1868Ile did not represent mutational hot spots. Login to comment 168 ABCA4 p.Asn1868Ile ABCA4 p.His423Arg In conclusion, the p.His423Arg and IVS10af9;5delG polymorphisms have a protective effect, whereas the p.Asn1868Ile polymorphism is a risk factor for disease. Login to comment