Objective: To identify the causative mutation in a Chinese family affected with dentinogenesis imperfecta shields type II (DGI-II).
Methods: With informed consent obtained from all participants, peripheral blood or chorionic villi samples were collected from the family members. Genomic DNA was extracted using a standard SDS-proteinase K-phenol/chloroform method. The whole coding region and exon/intron boundaries of the DSPP gene were amplified with polymerase chain reaction (PCR) and subjected to Sanger sequencing. To confirm the pathogenicity of the identified mutation, an Alu I recognition sequence was introduced into the mutant allele using mismatch primers by semi-nested PCR. Restriction fragment length polymorphism (RFLP) analysis was then carried out for all family members and 60 unrelated healthy controls. Meanwhile, mini-DSPP constructs were conducted to confirm the effect of the mutation in vitro.
Results: A splicing site mutation, c.52-1G>A, which was located upstream of exon 3, was found in all three patients and the fetus of the proband. Restriction analysis confirmed that all unaffected individuals and the 60 healthy controls did not carry the same mutation. The expression of minigene showed that the exon 3 of the DSPP gene was skipped during the transcription.
Conclusion: A novel pathogenic splicing-mutation c.52-1G>A has been detected in a Chinese family affected with DGI-II, which enabled prenatal diagnosis for the fetus of the proband.