Response to the letter “Simultaneous Molecular Haplotyping of Both IVS8 (TG)m and (T)n Tracts in the CFTR Gene: Still a Challenge” by Costa et al.

In their letter, Costa et al. addressed issues related to the clinical implementation of haplotype analysis of the poly(TG) and poly(T) repeat tracts in the cystic fibrosis transmembrane regulator ( CFTR ) gene by melting curve analysis. In esponse to their comments, we will describe the technical and logistic approaches we used to successfully implement this assay. We and Costa et al. have observed that some haplotype melting temperatures ( T ms) are very close together, as exemplified by the TG10–7T and TG11–9T alleles. Differentiation of clinical samples is facilitated by comparing both the T m and the curve shape with those for identical controls …