• Caused by mutations in CFTR (cystic fibrosis translocator) gene. (CTFR protein)
• Gene encodes a defective channel protein in membrane of cells, in exocrine glands
• CF-Glands secrete abnormally thick mucus due to osmotic imbalance.
• Interferes with breathing, pancreatic function, and allows growth of bacteria due to mucus
• Gene for CFTR located on human chromosome 7.
• In heterozygotes, harmful allele is masked but can still be passed on to offspring.
• Each chromosome has a short arm (p arm) and a long arm (q arm)
• Karyotype: a picture of the chromosomes in a cell that is used to check for abnormalities
• Akaryotype is created by staining the chromosomes with dye and photographing them.
• The photograph is then cut up and rearranged so that chromosomes are lined up into
• Pedigree Chart: shows genetic connections among individuals.
Autosomal Recessive Disorders
• If parents are both heterozygous (carriers), child will have a 25% chance of being affected
• Sex of offspring doesn’t affect chances because gene for disorder is on a non sex
chromosome (not X or Y)
• CF & Tay Sachs
• Phenylketonuria(PKU)–inability of the body to utilize the essential amino acid, phenylalanine.
Because the phenylalanine hydroxylase is decifient in turning it into tyrosine, problem with