[Phenotype predictions of the pathogenic nonsynonymous single nucleotide polymorphisms in deafness-causing gene COCH]

The COCH (Coagulation factor C homology) gene, located in human chromosome 14q12-q13, is the first gene identified to cause vestibular dysfunction. COCH encodes cochlin, which contains an N-terminal LCCL (Limulus factor C, cochlin, and late gestation lung protein Lgl1) domain and a C-temimal vWFA (Von Willebrand factor type A) domain. Recently, functional research of COCH mutations and cochlin have come under the spotlight in the field of hereditary deafness. Approximately 16 mutations in COCH have been confirmed to date, among which 13 non-synonymous single nucleotide polymorphisms (nsSNPs) are the most common form of genetic variations. Nonetheless, there is poor knowledge on the relationship between the genotype and the phenotype of the other nsSNPs in COCH. Here we analyzed deleterious nsSNPs from all SNPs in the COCH gene in the vWFA domain based on different computational methods and identified eight potential pathogenic nsSNPs (I176T, R180Q, G265E, V269L, I368N, I372T, R416C and Y424D) after combining literatures with 3D structures. Meanwhile, the protein structures of six reported pathogenic nsSNPs (P51S, G87W, I109N, I109T, W117R and F121S) in the LCCL domain have been constructed, and we identified aberrant structural changes in loops and chains. The prediction of pathogenic mutations for COCH nsSNPs will provide a blueprint for screening pathogenic mutations, and it will be beneficial to the functional research of COCH and cochlin in this field.