Mutations in A ₍₈₎ and A ₍₉₎ loci of exon 8 of retinoblastoma protein-interacting zinc finger gene of keloid patients

Objective To study the situation of the mutations in the A₍₈₎ and A₍₉₎ loci of exon 8 of retinoblastoma protein-interacting zinc finger gene (RIZ) of keloid patients. Methods From January 2003 to December 2007, 19 outpatient and hospitalized keloid patients of our hospital were conforming to the inclusion criteria. Both 3-5 g keloid tissue and 3 mL peripheral venous blood were collected from each patient to extract their genomic DNA, and the concentration was determined. The A₍₈₎ and A₍₉₎ loci fragments of exon 8 of RIZ were amplified by polymerase chain reaction (PCR). The length of product was detected by agarose gel electrophoresis, and DNA sequencing was performed after column chromatography. The mutations of A₍₈₎ and A₍₉₎ loci fragments were searched, and the types of mutations were determined. The consistency of genetic mutations of the keloid tissue and peripheral venous blood were compared. Data were processed with McNemar test. Results The DNA concentrations of the extracted keloid tissue and peripheral venous blood were 0.54 and 0.37 μg/μL, respectively, which were above 0.10 μg/μL. The lengths of PCR products of A₍₈₎ locus fragment DNA of exon 8 of RIZ from keloid tissue and peripheral venous blood were 235 and 238 bp, respectively, and those of A₍₉₎ locus were 242 and 244 bp, respectively, which were basically the same as the designed DNA fragments. PCR products purity of A₍₈₎ locus fragment DNA of exon 8 of RIZ from keloid tissue and peripheral venous blood were 1.81 and 1.75, respectively, and those of A₍₉₎ locus were 1.82 and 1.78, respectively, which were above 1.50. Mutations in the A₍₈₎ locus of exon 8 of RIZ were observed in keloid tissue of 18 patients, totally 6 gene mutations, including 4 point mutations and 2 frameshift mutations. Mutations in the A₍₉₎ locus of exon 8 of RIZ were observed in keloid tissue of 9 patients, totally 9 gene mutations, including 7 point mutations and 2 frameshift mutations. No patient had a mutation in the A₍₈₎ or A₍₉₎ locus of exon 8 of RIZ in peripheral venous blood. Compared with those of peripheral venous blood, the mutations in the A₍₈₎ and A₍₉₎ loci of exon 8 of RIZ in keloid tissue of patients were statistically significant (χ²=16.06, 7.11, P<0.05). Conclusions Point mutations and frameshift mutations occur in the A₍₈₎ and A₍₉₎ loci of exon 8 of RIZ in keloids of patients, which may be associated with the occurrence of keloids.