LMNA gene encodes Lamin A and C (Lamin A/C), which are intermediate filament protein implicating in DNA replication and transcription. Mutations in LMNA are validated to cause cardiac conduction disease (CCD) and cardiomyopathy.In a Chinese family, we identified 5 members harboring the identical heterozygous LMNA (c.686T>C, I229T) disease-causing mutation, which was not found in the 535 healthy controls. In silico analysis, we revealed structural alteration in Lamin A/C I229T mutant. Furthermore, molecular docking identified human polycomb repressive complex 2 and Lamin A/C interact with higher affinity in the presence of I229T, thus may downregulate Nav1.5 channel expression.Our findings expanded the spectrum of mutations associated with CCD and were valuable in the genetic diagnosis and clinical screening for CCD. Molecular docking analysis provided useful information of increased binding affinity between mutant Lamin A/C and polycomb repressive complex 2. However, the concrete mechanism of LMNA mutation (I229T) remains undetermined in our study, future genetics and molecular studies are still needed.