Human Genetic Disorders

Human Genetic Disorders

Chromosomal Mutations

• Disorder: Down Syndrome

  • Type of Mutation/Inheritance: Non-disjunction

  • Chromosome: 21

  • Chromosomal Issue: Trisomy

  • Symptoms/Effects:

    • Short stature

    • Round, full face

    • Oversized tongue

    • Intellectual disabilities

• Disorder: Patau Syndrome

  • Type of Mutation/Inheritance: Non-disjunction

  • Chromosome: 13

  • Chromosomal Issue: Trisomy

  • Symptoms/Effects:

    • Neural tube defects

    • Facial clefting (cleft lip, cleft palate)

    • Polydactyly

    • Intellectual disabilities

• Disorder: Klinefelter’s Syndrome

  • Type of Mutation/Inheritance: Non-disjunction

  • Chromosome: Sex Chromosome XXY

  • Chromosomal Issue: Trisomy

  • Symptoms/Effects:

    • Underdeveloped testes (sterile)

    • Overdeveloped breasts

    • Treated with hormones/surgery

• Disorder: Trisomy X

  • Type of Mutation/Inheritance: Non-disjunction

  • Chromosome: Sex Chromosome XXX

  • Chromosomal Issue: Trisomy

  • Symptoms/Effects:

    • Taller than average

    • Clumsiness

    • Possible intellectual disabilities

• Disorder: Turner’s Syndrome

  • Type of Mutation/Inheritance: Non-disjunction

  • Chromosome: Sex Chromosome XO

  • Chromosomal Issue: Monosomy

  • Symptoms/Effects:

    • Unexplained short stature

    • Short, webbed neck

    • Swollen hands and feet at birth

• Disorder: Cri-du-chat

  • Type of Mutation/Inheritance: Structural

  • Chromosome: 5

  • Chromosomal Issue: Deletion

  • Symptoms/Effects:

    • Various developmental abnormalities

    • Abnormal larynx causing a distinctive “cat-like” cry

Gene Mutations

• Disorder: Tay-Sachs

  • Type of Mutation/Inheritance: Point/Recessive

  • Chromosome: 15

  • Defective Protein: Hex A (hexosaminidase)

  • Symptoms/Effects:

    • Cannot break down fat in brain cells; lethal by age 5

• Disorder: Albinism

  • Type of Mutation/Inheritance: Point/Recessive

  • Chromosome: 11

  • Defective Protein: Tyrosinase protein

  • Symptoms/Effects:

    • Cannot produce melanin (skin, hair, and eye pigment); sensitive to UV rays from sunlight, necessitating protection

• Disorder: Sickle Cell Anemia

  • Type of Mutation/Inheritance: Point/Recessive

  • Chromosome: 11

  • Defective Protein: Hemoglobin A

  • Symptoms/Effects:

    • Produces hemoglobin S instead; causes red blood cells to elongate and appear sickle-shaped.

    • Red blood cells get obstructed, leading to pain

    • Treatment: Hydroxyurea

    • Higher incidence in individuals of African descent; heterozygotes are resistant to malaria, allowing the gene's persistence

• Disorder: PKU

  • Type of Mutation/Inheritance: Point/Recessive

  • Chromosome: 12

  • Defective Protein: Phenylalanine Hydroxylase

  • Symptoms/Effects:

    • Enzyme fails to break down phenylalanine, leading to a buildup that damages brain cells

• Disorder: Cystic Fibrosis

  • Type of Mutation/Inheritance: Point/Recessive

  • Chromosome: 7

  • Defective Protein: CFTR (Cystic Fibrosis Transmembrane Conductance Regulator)

  • Symptoms/Effects:

    • Inability to move chloride ions across respiratory membranes

    • Causes thick mucus production in lungs, which is coughed up and swallowed, leading to a buildup in the digestive tract

• Disorder: Huntington Chorea

  • Type of Mutation/Inheritance: Point/Dominant

  • Chromosome: 4

  • Defective Protein: Huntington protein

  • Symptoms/Effects:

    • Causes breakdown of brain cells

    • Late onset (after 30 years old)

    • CAG repeats 37-86 times instead of the normal 11-34 times

• Disorder: Achondroplasia

  • Type of Mutation/Inheritance: Point/Dominant

  • Chromosome: 4

  • Defective Protein: FGFR3 (Fibroblast Growth Factor Receptor 3)

  • Symptoms/Effects:

    • Mutant protein leads to premature conversion of cartilage to bone in long bones

    • Causes stunted growth of arms and legs

    • Genotypes: Dd = dwarfism; dd = normal; DD = lethal

• Disorder: Marfan Syndrome

  • Type of Mutation/Inheritance: Point/Dominant

  • Chromosome: 15

  • Defective Protein: Fibrillin protein

  • Symptoms/Effects:

    • Important for connective tissue development

    • Increased levels of growth factor protein (TGFB)

    • Characterized by tall stature, longer arm-span, and loose joints

• Disorder: Hemophilia

  • Type of Mutation/Inheritance: Point/Recessive

  • Chromosome: X

  • Defective Protein: Factor 8

  • Symptoms/Effects:

    • Blood cannot clot properly

    • Treatment involves clotting factors (now man-made due to HIV risks in early 1980s)

• Disorder: Duchenne Muscular Dystrophy

  • Type of Mutation/Inheritance: Point/Recessive

  • Chromosome: X

  • Defective Protein: Dystrophin protein

  • Symptoms/Effects:

    • Faulty muscle protein leads to early muscle breakdown in childhood

• Disorder: Colorblindness

  • Type of Mutation/Inheritance: Point/Recessive

  • Chromosome: X

  • Defective Protein: Receptor proteins

  • Symptoms/Effects:

    • Variability in color detection by the eye, dependent on the defective protein

    • Most common form is red-green colorblindness

• Disorder: Fragile X

  • Type of Mutation/Inheritance: Point/Recessive

  • Chromosome: X

  • Defective Protein: FMR1 protein

  • Symptoms/Effects:

    • Essential for proper neurological development

    • Severity of intellectual disability correlates with the number of CGG repeats in the gene.