2.5.2 Patterns of Inheritance

• Genetic disorders are caused by mutations in an individual's DNA
• What are the main modes of inheritance for genetic disorders?

  Autosomal, X-linked
• In autosomal dominant inheritance, a single copy of the mutated gene is enough to cause the disorder.
• Two copies of the mutated gene are needed in autosomal recessive inheritance to cause the disorder.
• In X-linked inheritance, the mutated gene is located on the Y chromosome.

  False
• Match the mode of inheritance with its example disorder:

  Autosomal Dominant ↔️ Huntington's disease

  Autosomal Recessive ↔️ Cystic Fibrosis

  X-linked ↔️ Hemophilia A
• What is an example of an autosomal dominant disorder?

  Huntington's disease
• In autosomal dominant inheritance, an affected individual typically has at least one affected parent
• If one parent is affected by an autosomal dominant disorder, there is a50% chance their offspring will inherit the disorder.
• Which gene is mutated in Huntington's disease?

  HTT
• Genetic disorders can only be inherited, not arise spontaneously.

  False
• Match the type of genetic disorder with its inheritance pattern:

  Dominant ↔️ One mutated gene copy

  Recessive ↔️ Two mutated gene copies
• What must both parents be to pass on a recessive genetic disorder?

  Carriers
• Genetic disorders are caused by a mutation in an individual's genetic material (DNA).mutation
• Genetic disorders can arise spontaneously.
• What type of inheritance requires only one mutated gene copy to cause a disorder?

  Dominant
• Recessive genetic disorders require two mutated gene copies, one from each parent.parent
• What is the primary cause of genetic disorders?

  DNA mutations
• Match the mode of inheritance with its example disorder:

  Autosomal Dominant ↔️ Huntington's disease

  Autosomal Recessive ↔️ Cystic Fibrosis

  X-linked ↔️ Hemophilia A
• In autosomal dominant inheritance, every affected individual has at least one affected parent.
• Both males and females can be affected by autosomal dominant disorders because the mutated gene is on a non-sex chromosome.chromosome
• Which gene is mutated in Huntington's disease?

  $HTT$
• In autosomal recessive inheritance, both parents must be carriers for their child to inherit the disorder.
• Cystic fibrosis is caused by mutations in the $CFTR$ gene, affecting about 1 in 2,500 births in European populations.populations
• Arrange the steps of X-linked dominant inheritance in order:

  1️⃣ One mutated gene on X chromosome is needed

  2️⃣ Affected females may pass the mutation to half their daughters and sons

  3️⃣ Affected males pass the mutation to all daughters
• Males are more likely to be affected by X-linked recessive disorders because they have only one X chromosome.
• Which X-linked recessive disorder is caused by mutations in the $F8$ gene?


  Hemophilia A
• Y-linked inheritance occurs when a mutated gene is located on the Y chromosome, which only males possess.Y
• Mitochondrial inheritance affects both males and females and is only passed down from the mother.
• Which mitochondrial disorder is caused by mutations in mtDNA and affects vision?

  LHON