Mutation & Genetic Disorders

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Mutation & Genetic Disorders

Mutation

• A change in the DNA sequence that may affect whole chromosomes or just one gene.

Kinds of Mutation

• Chromosomal Mutation
• Gene Mutation

Causes of Mutation

• DNA fails to copy accurately
• External influnces
  • Chemicals
  • Radiation
  • Infectious agents

Gene Mutation

Two Classifications:

• Hereditary Mutation
  • A mutation inherited from the parents.
  • Also known as germline mutations.
• Acquired Mutations
  • Caused by external factors.
  • Also known as somatic mutations.

Types of Mutations:

Deletion Mutation

• When a single nucleotide gets deleted and the whole sequence gets shifted to the left.
• Can cause Cat's Cry Syndrome, Cystic Fibrosis.

Insertion Mutation

• When a single nucleotide gets inserted and the whole sequence gets shifted to the right.
• Can cause Huntington's disease.

Inversion Mutation

• When a chromosome breaks out and is reinserted backwards.
• Can cause Haemophilia.

Translocation Mutation

• When a part of the chromosome breaks off and is added to a different chromosome.
• Can cause Alagille's Syndrome, problems in the liver due to irregular bile secretions, and Burkitt Lymphoma.

Missense Mutation

• When a single nucleotide gets replaced by a different nucleotide causing the wrong amino acid.
• Can cause Sickle Cell Anemia, Tay-Sachs Disease

Nonsense Mutation

• When a single nucleotide gets replaced by a different nucleotide making a stop codon causing the sequence to be shortened.

Frameshift Mutation

• When the reading of the DNA bases gets shifted causing a different sequence.

Repeated Expansion Mutation

• When nucleotide are repeated several times causing a repeated amino acid in the sequence.
• Can cause malfunctioned proteins.

Duplication Mutation

• When a certain piece of the DNA is abnormally copied several times.
• Can cause Charcot-Marie-Tooth Disease.

Chromosomal Mutation

• Unpredictable change that happens to the chromosome.
• Often occurs during meiosis by mutagens.
• Can result in changes in the number of chromosomes or changes in the structure of a chromosome.

Autosomal Aneuploidy

• Causes an abnormal number of chromosomes.
  • Monosomy
  • Trisomy
• Caused by problem during meiosis

Errors in Disjunction

• Non-Disjunction
  • Failure of homologous chromosome to seperate properly during meiosis

Trisomy 21

• Extra Chromosome on number 21.
• AKA Down Syndrome
• Flattened Nose and Face, Upward slanting of eyes.
• Can be caused by the mother's age.

Trisomy 18

• Extra Chromosome on number 18
• AKA Edward Syndome
• Small Head, Cleft Palate, Sterile.

Trisomy 13

• Extra Chromosome on number 13
• AKA Patau's Syndrome
• Small Head, Low-set Ears, Heart defects, Brain development problems.

Klinefelter Syndrom

• Extra sex chromosome.
• Longer fingers and arms, Delicate Skin, Sterile.
• Tends to have a normal lifespan.

Monosomy

• Deficient number of chromosomes

Turner's Syndrome

• Missing a chromosome in the sex chromosome.
• Rudimentary ovaries, Constricted aorta, No menstruation, Unusual facial features, Sterile.

Albinism

• Inability to produce melanin.
• Vulnerable to skin cancers.

Autosomal Disorders

• Amyotrophic Lateral Scleerosis (ALS)
• Breast Cancer
• Polycystic Kidney Disease
• Alzheimer Disease
• Sickle-Cell Anemia
• Phenylketonuria (PKU)
• Melanoma
• Cystic Fibrosis

Other Forms of Genetic Disorders

• Cleft Palate
• Heart Disease
• Obesity
• Infertility
• Cancers
• Asthma
• Intellectual Disability