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
• What are genetic disorders caused by?

  Mutations in DNA
• Genetic disorders can be inherited or arise spontaneously
• Genetic disorders affect both physical and cognitive development.
• How many mutated gene copies are required for a dominant genetic disorder to manifest?

  One
• Recessive genetic disorders require two mutated gene copies and both parents must be carriers
• Order the types of genetic disorders by their inheritance pattern.

  1️⃣ Autosomal Dominant

  2️⃣ Autosomal Recessive

  3️⃣ X-linked
• Match the mode of inheritance with an example disorder:

  Autosomal Dominant ↔️ Huntington's disease

  Autosomal Recessive ↔️ Cystic Fibrosis

  X-linked ↔️ Hemophilia A
• Cystic fibrosis is an example of an autosomal dominant disorder.

  False
• What does autosomal dominant inheritance require to cause a genetic disorder?

  One mutated gene copy
• In autosomal dominant inheritance, sex chromosome involvement is no
• Every affected individual in autosomal dominant inheritance has at least one affected parent.
• Which gene is mutated in Huntington's disease?

  HTT
• What is required for autosomal recessive inheritance to cause a disorder?

  Two mutated gene copies
• In autosomal recessive inheritance, the disorder may skip generations
• Cystic fibrosis affects approximately 1 in 2,500 births in European populations.
• How is X-linked dominant inheritance passed on from an affected father to his children?

  All daughters, no sons
• Match the X-linked dominant disorder with its affected gene:

  Hypophosphatemic Rickets ↔️ PHEX

  Rett Syndrome ↔️ MECP2
• In X-linked recessive inheritance, males are more likely to be affected because they have only one X chromosome.
• Carriers of X-linked recessive disorders are always female.
• Which gene is mutated in Hemophilia A?

  F8
• What is unique about Y-linked inheritance?

  Only affects males
• In mitochondrial inheritance, genetic traits are passed down solely from the mother
• Which disorder is caused by mutations in mitochondrial DNA?

  Leber's Hereditary Optic Neuropathy
• Order the steps for interpreting a pedigree chart.

  1️⃣ Identify squares and circles

  2️⃣ Identify shaded and unshaded symbols

  3️⃣ Analyze horizontal and vertical lines

  4️⃣ Interpret Roman and Arabic numerals