 |  | | | | Types (classes) of CFTR mutations. |
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All individuals carry two copies of the CFTR gene, one inherited from the father and one inherited from the mother. To have CF, an individual must have two abnormal copies - or mutations - of the CFTR gene. If the individual has only one mutation, he or she will not be affected with CF, but will be a “carrier”. Because carriers have one abnormal CFTR gene, they can pass this gene to their offspring, placing their children at risk for CF. More than 1,000 CFTR mutations have been identified. In white populations, the most common mutation is called the ?F508 mutation, and occurs in approximately 70 percent of CF patients. Commercially available mutation screening panels detect most cases of CF. The accuracy of the test will depend on how many mutations are tested and the ethnic origin of the patient (see table below). However, because there are so many described mutations and many more that have not been identified, some patients with clinical features of CF may have only one or no CFTR gene mutations identified by mutation analysis. For these individuals, additional testing may include nasal potential difference, CT scans of the chest or sinuses, cultures of airway mucus, and evaluation of stool elastase. Detection of Cystic Fibrosis by Mutation Analysis | 25 Mutation Test | | Ethnic Group | Detection Rate | | Caucasian | 90% | | African American | 69% | | Hispanic | 57% | | Ashkenazi Jewish | 97% | | Other | unknown |
| 97 Mutation Test | | Ethnic Group | Detection Rate | | Caucasian | 93% | | African American | 81% | | Hispanic | 78% | | Ashkenazi Jewish | 97% | | Other | unknown |
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