CFHockeyMom
New member
First, welcome to our "home". The CF diagnosis is tough but as you'll see here, it's not the end of the world. There is so much love, support, and information here that for many of us, well, it's the only place we can talk to people that truly understand.
Now as for your questions...
DF508 is considered a Class II mutation which results in defective trafficking of CFTR so that it does not reach the apical surface membrane where it is intended to function.
R117H is typically considered a Class IV mutation which results in a normal amount of functional CFTR at the cell membrane, but chloride conductance is reduced. These mutations are generally associated with a pancreatic sufficiency. However if the variant on the R117H is associated with a 5T versus a 7T or 9T then it is usually presents as more classic CF.
Here is some info Allie posted on gene classes and a study that looked into gene/class combinations...
Genotype-phenotype correlation for pulmonary function in cystic fibrosis.de Gracia J, Mata F, Alvarez A, Casals T, Gatner S, Vendrell M, de la Rosa D, Guarner L, Hermosilla E.
Department of Pneumology, Hospital general Vall d'Hebron, Barcelona, Spain. jgracia@separ.es
BACKGROUND: Since the CFTR gene was cloned, more than 1000 mutations have been identified. To date, a clear relationship has not been established between genotype and the progression of lung damage. A study was undertaken of the relationship between genotype, progression of lung disease, and survival in adult patients with cystic fibrosis (CF). METHODS: A prospective cohort of adult patients with CF and two CFTR mutations followed up in an adult cystic fibrosis unit was analysed. Patients were classified according to functional effects of classes of CFTR mutations and were grouped based on the CFTR molecular position on the epithelial cell surface (I-II/I-II, I-II/III-V). Spirometric values, progression of lung disease, probability of survival, and clinical characteristics were analysed between groups. RESULTS: Seventy four patients were included in the study. Patients with genotype I-II/I-II had significantly lower current spirometric values (p < 0.001), greater loss of pulmonary function (p < 0.04), a higher proportion of end-stage lung disease (p < 0.001), a higher risk of suffering from moderate to severe lung disease (odds ratio 7.12 (95% CI 1.3 to 40.5)) and a lower probability of survival than patients with genotype I-II/III, I-II/IV and I-II/V (p < 0.001). CONCLUSIONS: The presence of class I or II mutations on both chromosomes is associated with worse respiratory disease and a lower probability of survival.
And as I've said many times...
<div class="FTQUOTE"><begin quote>We have plenty of people on the forum here that have the same genotypes but completely different clinical outcomes. Environment, compliance, quality of care, bacteria cultured, and luck all contribute to clinical outcome.
A lot of parent's of newly diagnosed CFer's are keen to know what their child's genes/mutations will mean for their child in terms of clinical outcome. Unfortunately, genes/mutations don't necessarily predict clinical outcome and at the end of the day, all you really know is that your child has CF.
Regardless of gene class/type or symptoms, I encourage you to be very proactive with your daughters care. When it comes to CF the old saying, "An ounce of prevention is worth a pound of cure", couldn't be more true.</end quote></div>
Now as for your questions...
DF508 is considered a Class II mutation which results in defective trafficking of CFTR so that it does not reach the apical surface membrane where it is intended to function.
R117H is typically considered a Class IV mutation which results in a normal amount of functional CFTR at the cell membrane, but chloride conductance is reduced. These mutations are generally associated with a pancreatic sufficiency. However if the variant on the R117H is associated with a 5T versus a 7T or 9T then it is usually presents as more classic CF.
Here is some info Allie posted on gene classes and a study that looked into gene/class combinations...
Genotype-phenotype correlation for pulmonary function in cystic fibrosis.de Gracia J, Mata F, Alvarez A, Casals T, Gatner S, Vendrell M, de la Rosa D, Guarner L, Hermosilla E.
Department of Pneumology, Hospital general Vall d'Hebron, Barcelona, Spain. jgracia@separ.es
BACKGROUND: Since the CFTR gene was cloned, more than 1000 mutations have been identified. To date, a clear relationship has not been established between genotype and the progression of lung damage. A study was undertaken of the relationship between genotype, progression of lung disease, and survival in adult patients with cystic fibrosis (CF). METHODS: A prospective cohort of adult patients with CF and two CFTR mutations followed up in an adult cystic fibrosis unit was analysed. Patients were classified according to functional effects of classes of CFTR mutations and were grouped based on the CFTR molecular position on the epithelial cell surface (I-II/I-II, I-II/III-V). Spirometric values, progression of lung disease, probability of survival, and clinical characteristics were analysed between groups. RESULTS: Seventy four patients were included in the study. Patients with genotype I-II/I-II had significantly lower current spirometric values (p < 0.001), greater loss of pulmonary function (p < 0.04), a higher proportion of end-stage lung disease (p < 0.001), a higher risk of suffering from moderate to severe lung disease (odds ratio 7.12 (95% CI 1.3 to 40.5)) and a lower probability of survival than patients with genotype I-II/III, I-II/IV and I-II/V (p < 0.001). CONCLUSIONS: The presence of class I or II mutations on both chromosomes is associated with worse respiratory disease and a lower probability of survival.
And as I've said many times...
<div class="FTQUOTE"><begin quote>We have plenty of people on the forum here that have the same genotypes but completely different clinical outcomes. Environment, compliance, quality of care, bacteria cultured, and luck all contribute to clinical outcome.
A lot of parent's of newly diagnosed CFer's are keen to know what their child's genes/mutations will mean for their child in terms of clinical outcome. Unfortunately, genes/mutations don't necessarily predict clinical outcome and at the end of the day, all you really know is that your child has CF.
Regardless of gene class/type or symptoms, I encourage you to be very proactive with your daughters care. When it comes to CF the old saying, "An ounce of prevention is worth a pound of cure", couldn't be more true.</end quote></div>