inherited disorders

• Inherited disorders are conditions that can be passed on through alleles from parents
• Examples of inherited disorders are polydactyly and cystic fibrosis
• Polydactyly is a condition where a baby is born with extra fingers or toes, caused by a dominant allele
• Even if only one of the two alleles is the polydactyly allele, the individual will still have the disorder
• Crossing a heterozygous individual with a homozygous normal individual can result in offspring with a 1:1 ratio of polydactyly to normal phenotypes
• Cystic fibrosis is caused by a recessive allele and is a disorder of the cell membranes
• It results in the release of thick sticky mucus in different parts of the body, particularly the airways of the lungs and in the pancreas
• Most people have the normal homozygous dominant genotype, but carriers have one copy of the cystic fibrosis allele
• Carriers can potentially pass on the cystic fibrosis allele to their children
• Crossing two carriers can result in offspring with a 3:1 ratio of normal to cystic fibrosis phenotypes
• Embryo screening is a process where genetic disorders like polydactyly and cystic fibrosis can be detected in embryos
• If alleles that could cause a disorder are found, parents and doctors might decide to discard that embryo and use a different one instead
• Advantages of embryo screening:

  • Helps reduce overall suffering by preventing health problems
  • Saves money by avoiding expensive treatments
• Concerns of embryo screening:

  • Implies that people with genetic problems are less desirable, potentially increasing prejudice
  • Future screening for other traits like eye color or physique could be a concern