Polymorphisms in COL4A3 and COL4A4 genes associated with keratoconus

[摘要] Purpose: Alterations in collagen typeIV, alpha-3 (COL4A3) and collagen type IV, alpha-4 (COL4A4)genesmay be responsible for a decrease in collagen types I and III, afeature often detected in keratoconus (KC). To evaluate thesignificance of alterations in COL4A3 and COL4A4 genesin KC patients, we screened both genes and estimated the significanceof polymorphisms in Slovenian patients with KC. Methods: The study included 104unrelated patients with KC and 157 healthy blood donors. Diagnosis wasestablished by clinical examination, electronic refractometry, andkeratometry. DNA was extracted from blood, and gene exons wereamplified by PCR. Non-isotopic high-resolution single-strandedconformation analysis (SSCA) was used to screen COL4A3 and COL4A4genes, and migration shifts detected by SSCA were subsequentlysequenced. For statistical evaluation, control blood donors were chosenaccording to age, sex, and not having blood relationship. Neitherpatients nor control blood donors chosen for statistical analysis werein blood relationship. We used Fisher’s exact test for statisticalevaluation, with p<0.05 considered significant. Results: We detected eight polymorphismsin the COL4A3 gene and six in the COL4A4 gene. Alleledifferences in D326Y in COL4A3 and M1237V and F1644F in COL4A4are significantly distinctive of KC patients (Fisher’s exact test,p<0.05). When analyzing different genotypes under three models(dominant, recessive, and additive), we established that P141L, D326Y,and G895G in COL4A3 and P482S, M1327V, V1516V, and F1644F in COL4A4have significant differences in genotype distribution between KCpatients and the control group. Conclusions: This is the firstmutational screening of COL4A3 and COL4A4 genes in KCpatients to establish the status of these genes and compare them to acontrol population. Analysis of COL4A3 and COL4A4revealed no mutations related to KC patients, but specific genotypes ofseven previously described polymorphisms are significantly associatedwith KC under dominant, recessive, or additive models. Differences inthe expression of type IV collagen in previously published data aboutchromosomal instabilities in the regions in which the analyzed geneswere mapped and our data indicate a probability that some of thepolymorphisms we detected could be related to KC.

[学科分类] 生物化学/生物物理