Revision slides on mendelian inheritance_BB

Types of Mendelian Inheritance

• Autosomal Recessive

  • Phenotype can skip generations.

  • Both parents must be carriers to transmit the trait to offspring.

  • Affects males and females equally.

• Autosomal Dominant

  • Phenotype appears in every generation and affects males and females equally.

  • Sometimes the homozygous mutant is lethal.

Autosomal Alleles

Autosomal Dominant

• Key Characteristics:

  • Every generation shows affected individuals.

  • Example Genotypes:

    • Aa (heterozygous)

    • AA (homozygous dominant)

    • aa (homozygous recessive) - lethal condition in homozygous state.

Autosomal Recessive

• Key Characteristics:

  • Can skip generations; traits may not appear in every generation.

  • Example Genotypes:

    • Parents: Aa x Aa → 25% AA, 50% Aa, 25% aa (expected outcomes).

X-Linked Inheritance

X-Linked Dominant

• Key Characteristics:

  • Affected males pass the condition to all their daughters, but none of their sons (no male-to-male transmission).

  • Affected heterozygous females with unaffected male partners transmit the condition to half their sons and daughters.

  • Example Genotypes:

    • XdXd (affected female), XDY (unaffected male), XDXd (heterozygous female).

  • Rare mutations, e.g., Rett syndrome (occurs in 1/10,000 female births).

X-Linked Recessive

1. Transmission through Unaffected Carrier Female:

   • Half of sons are predicted to be affected.

   • Daughters: half are predicted to be carriers (none affected).

   • Example Genotypes:

     • XAXa (carrier female), XaY (affected male).

2. Transmission through Hemizygous Affected Male:

   • None of the sons affected, all daughters are carriers.

   • Example Genotypes:

     • XAY (unaffected male), XAXa (carrier female).

3. Transmission through Affected Female:

   • All sons will be affected, and all daughters will be carriers.

   • Example Genotypes:

     • XAXa (affected female), XaY (affected male).