Unit 2 - Lesson 6 - Genetic Disorders

Genetic Disorder

A disease or disorder that is caused by a genetic mutation

Causes

  • Germline Mutation

    • change in DNA sequence

  • Chromosonal Mutation

    • non-disjunction event in meiosis

Gene (point) Mutations

  • Caused by mutagens (UV, radiation, chemicals)

  • Mutations in body cells can lead to cancer

  • Mutations in sex cells can be passed down to offspring

  • Spontanious or inherited

Types of Mutations

  • Good - Offspring survive better + reproduce

  • Bad - harm to organism and offspring

  • Benign - no harm to offspring

Patterns of inheritance

  • Autosomal Dominant

    • Non sex-chromosomes

    • Huntington’s disease (nerve cells break down and die)

  • Autosomal Recessive

    • Non sex-chromosomes

    • Cystic fibrosis (excessive mucus production in lungs)

  • Sex-linked recessive

    • X-Chromosome

    • Hemophilia (blood doesn’t clot regularly)

  • Codominant

    • non sex-chromosome

    • Sickle cell anemia (reb blood cell is half mooned)

Chromosonal Mutations

  • Homologous chromosomes or chromatid stick together instead of seperating during meiosis

Resulting Genetic Disorders

XXX Female

  • Infertile

  • Most are taller

  • Delays in puberty

  • 47 chromosomes

XXY Klinefelter’s Male

  • Infertile

  • 47 Chromosomes

  • Do not reproduce testostrone properly

  • Some female characteristics

XO Turner’s Female

  • Infertile

  • Short stature

  • 45 chromosomes

  • Only surviving condition with 45 chromosomes

Autosomal Non-disjunction

  • Autosomal Monosomics

    • Can’t survive

  • Trisomy - 13, 15, 18

    • Severe defects

    • 3 month life-span

  • Trisomy - 21 (Down syndrome)

    • Survive to adults

    • Skeletal defects and poor tonage

    • Intellectual disabilities

Karyotypes

  • Show the full set of choromosomes of an idividual