How are poly T/TG variants interpreted?

Experiments clearly show that a T5 allele leads to the exclusion of exon 10 and the production of a non-functional protein (PMID: 7691356, 7684641, 10556281, 14685937, 216586497). In a mini-gene assay, exon 10 exclusion was 4% for the TG11-T5 allele, 10% for TG12-T5 and 18% for TG13-T5 (PMID: 10556281). The TG12-5T and TG13-5T alleles are reported to cause congenital absence of vas deferens (CAVD) in males and a non-classic form of cystic fibrosis (CF) when homozygous or present in trans with a second pathogenic CFTR mutation (PMID: 14685937). The TG11-T5 allele is reported to cause congenital bilateral absence of vas deferens (CBAVD) in males when present in trans with a second pathogenic CFTR mutation (PMID: 14685937). However, these individuals do not have symptoms of cystic fibrosis. When the 5T allele is found in trans with a severe CF mutation, the odds of disease are 30 times greater for TG12 and TG13 than for TG11 (PMID: 14685937). We classify the TG12-T5 and TG13-T5 alleles as pathogenic. The TG11-T5 allele is classified as pathogenic (low penetrance). Any alleles with T7 or T9 are classified benign and we do not include them in the primary report.