New Report of a Different Clinical Presentation of Splicing Mutation (c.351+2T>C): Could be Considered as a Potential Modifier Gene for ?

CD151, a member of the tetraspanin family, is essential for normal development of skin and kidney. To date, only 2 pathogenic variants of the gene have been identified in a related disorder with recessive inheritance. Here, in the third study of mutations, we report 3 affected siblings presenting variable degrees of renal and dermal symptoms. Whole exome sequencing (WES) was performed on the proband, followed by data analysis and in silico assessments. Confirmation of the mutation in the other patients were carried out using Sanger sequencing. The consequence of the mutation was investigated by RNA extraction and Sanger sequencing of PCR products from cDNA. Multiple computational tools were applied for protein alignment, homology modeling, and molecular interaction analysis. WES revealed the variant c.351+2T>C, NM_139029 (GRCh37) in , and this was confirmed by Sanger sequencing in all patients. This variant is the result of a substitution of nucleotide T with C that changes the position +2 of the donor splice site in intron 5, leading to total loss of exon 5 from the transcript. The mentioned variant was not found in population allele frequency databases, and prediction tools concurred in its damaging effect on the protein. Based on the criteria from ACMG guidelines, this variant is pathogenic. Interestingly, in terms of clinical findings, symptoms and severity of the disease in the patients in this study were different compared to the previous report of the mutation and the disease. In addition, in silico analysis in this study appears to suggest a candidate protein, Tetraspanin-11 (TSPAN11), that could partially modify CD151 functions. This study supports the pathogenic effect of the variant c.351+2T>C, highlights the extensive variable expressivity amongst patients, reinforces the contribution of genomic content to clinical characteristics of mutations, and accentuates the importance of modifier genes.