cystic fibrosis

cystic fibrosis is due to mutations in the cystic fibrosis
conductance regulator (CFTR) gene which is a chloride ion
channel disease affecting conductance pathways for salt and
water in epithelial cells. Decreased fluid and salt secretion is
responsible for the blockage of exocrine outflow from the
pancreas, accumulation of mucus in the airways and defective
reabsorption of salt in the sweat glands. Family studies localised
the gene causing cystic fibrosis to chromosome 7q31 in 1985
and the use of linked markers in affected families enabled
carrier detection and prenatal diagnosis. Prior to this, carrier
detection tests were not available and prenatal diagnosis, only
possible for couples who already had an affected child, relied
on measurement of microvillar enzymes in amniotic fluid – a
test that was associated with both false positive and false
negative results.