I was thinking of you yesterday when I read this - I somehow got to it from the CDC website. I don't know exactly how old it is but it is at least from 2002 or later:
<br /><b>The R117H mutation and reflexive testing</b>
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<br /><i>Based on analyses of the CFTR gene in affected and unaffected individuals, it was determined that a gene modifier determined the phenotype associated with the R117H mutation when it was combined with another mutation (e.g., delF508) (Kiesewetter, 1993). The impact of R117H is dependent on the length of the polypyrimidine tract located in intron 8. Three length variants have been identified and designated 5T, 7T and 9T. These are found in about 5 percent, 10 percent and 85 percent of the general population, respectively. This Poly-T variant occurs in a noncoding region of the gene several exons removed from the R117H location (exon 4), but it affects gene expression by influencing splicing efficiency. The phenotypic variation is molecularly based and determined by whether the R117H mutation is located on the same (cis) or opposite (trans) chromosome 7. In order for this mutation to produce a severe phenotype, it must be 1) associated with the 5T variant on the same chromosome (in cis), and 2) the other chromosome must also carry a CF mutation that is capable of producing the phenotype. In the setting of prenatal screening, the ACMG has recommended that Poly-T testing be performed only as a reflex test for carriers shown to be heterozygous for the R117H mutation (Grody et al., 2001).
<br />For example, a pregnant woman is found to be a carrier of the R117H mutation. Reflexive testing is performed to determine whether she carries the 5T polymorphism. In 95 percent of women tested, the polymorphism will be either 7T or 9T, and the woman can be informed that the mutation will not be associated with classic cystic fibrosis in the fetus, even if the partner if found to be a carrier. No further testing is required. </i>
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<br />Okay, so at the time this was written the authors felt that 7T will not result in "Classic CF", if I'm reading this right. But you have found articles that suggest it <b>can</b> develop, and Alyssa's children, in real life, have also developed sypmtoms.
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<br />The attitude of your relatives - are they in "hopeful denial", but still supportive, or are do they think you are putting your child, yourselves, and them through all of this for "nothing"? Because, to be honest, I don't understand the latter if that is their attitude.
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<br />Nothing can be "clear" to ANYone when it comes to the human body, you know? Some folks live to be 106 and drink or smoke, some young healthy athletes keel over playing basketball. Call it what you will - genetic potential, predisposition, etc. - but you have identified that Abby has CF. Why would this be any different than if I knew that I was going to die of a heart attack at age 50 unless I spent two hours a day exercising. I know it doesn't help you for me to rant; sorry. <img src="i/expressions/face-icon-small-frown.gif" border="0">
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