Cystic fibrosis is the most common lethal inherited disease, affecting about 30,000 patients worldwide. In the past decade, strides in patient management and the development of new pharmacological agents, coupled with scientific and technological advances, have increased the mean life expectancy of CF patients to approximately 30 years of age (approximately 50% of CF patients live to the age of 30). As early as 30 years ago, the median survival age was 8 years. Chronic lung infections, which lead to declines in lung function, remain the major cause of morbidity and mortality. While several pathogens have been implicated, Pseudomonas aeruginosa—an opportunistic and virulent bacterium—has an affinity for the lung tissue of CF patients. New research efforts, focused on gene mapping as a possible mechanism to identify mutations correlating with increased bacterial virulence, may lead to new therapeutic discoveries and enhanced patient outcomes (Smith, 1999).
A pair of genes that are not working properly causes cystic fibrosis. There are more than 700 different mutations that cause cystic fibrosis; however, most cases of CF are caused by relatively few mutations. This makes it possible to screen for CF carriers. The eight most common mutations in CF chromosomes are DF508, 3 mutations in exon 11-G542X, G551D, R553X, a slice mutation 621+1G-T, and mutations in amino acids 1282, 1303, and 455. These account for about 80 to 85% of the mutations in the Caucasian population. Detection rates may vary with ethnic background. Because not all cystic fibrosis mutations are detectable, a negative result does not mean that the patient is not a carrier (Lory, 1999).
The most common mutation is referred to as the DF508 deletion. In Caucasian Americans with cystic fibrosis:
· 50% have two copies of DF508
· 40% have one copy of the deletion and one other mutation
· 10% do not have the DF508 deletion
In CF carriers of other ethnic backgrounds, the DF508 deletion is present in:
· 45% of Italians
· 30% of African Americans
· 30% of Ashkenazi Jews
The type of genetic testing used to detect the DF508 deletion and other mutations is called direct testing. Current testing readily detects up to 90% of carriers in the North European Caucasian population lining in North American and 95% of the CF carriers in the Ashkenazi Jewish population. Approximately 50% of carriers in Hispanic and African American populations are detectable (Lory, 1999).
Cystic fibrosis is an inherited disorder that affects many functions of the body: breathing, digestion, and reproduction. The lifelong illness usually gets more severe with age and can affect both males and female equally. The symptoms and severity of cystic fibrosis differ from person to person. Most patients have both respiratory and digestive problems, while others only have respiratory problems. Intelligence is not affected in people with CF.