A case of classical Vohwinkel syndrome caused by the mutation p.N54H in the GJB2 gene / 中华皮肤科杂志

Objective:To detect gene mutations in 1 patient with Vohwinkel syndrome who presented with palmoplantar keratoderma, pseudo-ainhum and deafness.Methods:Clinical data were collected from the proband, and a genetic test was performed to identify mutation sites.Results:Clinical manifestations of the proband were consistent with classical Vohwinkel syndrome. The genetic test revealed a heterozygous mutation c.160A>C (p.N54H) in the GJB2 gene, which was not detected in her parents or healthy controls.Conclusion:The heterozygous mutation c.160A>C (p.N54H) in the GJB2 gene was first identified in a patient with classical Vohwinkel syndrome, and there were overlaps in mutation sites between classical Vohwinkel syndrome and palmoplantar keratoderma with deafness.

Mutation analysis of GJB2 gene in a family with Vohwinkel syndrome / 中华皮肤科杂志

ObjectiveTo detect the mutation of GJB2 gene in a Chinese family with Vohwinkel syndrome.MethodsClinical data were collected from 5 patients with Vohwinkel syndrome in a family,and blood samples were obtained from the 5 patients and 4 unaffected individuals in the family as well as from 100 normal human controls.Genomic DNA was extracted and subjected to PCR for the amplification of the entire encoding and flanking sequences of GJB2 gene(1015 bp) followed by bidirectional sequencing with the ABI PRISM 3730 automatic DNA sequencer.Finally,sequence alignment was carried out by using the software Sequencher 4.10.1 Demo.ResultsA heterozygous missense mutation 196G→C in the GJB2 gene,which resulted in the substitution of aspartic acid by histidine at codon 66 (D66H) in the first extracellular domain of the protein,was observed in all the patients of this family,but in none of the 4 unaffected individuals in this family or the 100 normal human controls.ConclusionThe D66H missense mutation in the GJB2 gene may contribute to the occurrence of Vohwinkel syndrome in Chinese Han population.

In Silico Study of Human Gap Junction Beta-2 Protein by Homology Modeling

Asp66his, Asp54Lys, and Asp50Asn are mutations in connexin 26 that are observed in the clinic and give rise to autosomal dominant syndromes. They are the result of point mutations in the human gap junction beta-2 gene. In order to investigate the structural mechanism of Bart-Pumphrey Syndrome, Keratitis-Ichthyosis-Deafness Syndrome, and Vohwinkel Syndrome, homology modeling was carried out. Asp66 has direct contact with Asn62 by two hydrogen bonds in the wild-type protein, and in Asp66His, the biggest change observed is a tremendous energy increase caused by hydrogen bond breakage to Asn62. Shifts in the side chain and new hydrogen bond formation are observed for Lys54 compared to the wild-type protein (Asn54) and result in closer contact to Val84. Asp50Asn causes a significant decrease in bond energy, and residual charge reversal repels the ion and metabolites and, hence, inhibits their transportation. Such perturbations are likely to be a factor contributing to abnormal functioning of ion channels, resulting cell death and disease.