Many of the phenotypes of DiGeorge syndrome have been traced back to one of the genes that is in the deleted region, TBX1. Some of the evidence for the important role of TBX1 in DiGeorge syndrome came from individuals who have some of the symptoms of DiGeorge syndrome without having the typical deletion. Closer examination showed that some of these individuals had SNV in the TBX1 gene. Which of the following SNVS would be most likely to create a similar phenotype to the deletion? A. A variant in the promoter region of TBX1 that increases its expression
B. A variant in the intronic region of TBX1 that does not affect splicing. X
C. A nonsense variant near the 5' end of the TBX1 gene.
D. A silent variant near the 5' end of the TBX1 gene.