Genetic disorders can be either inherited or not inherited.
Inherited diseases
A disease inherited from parents (vertical transmission). But all the diseases inherited from parents are not genetic disorders.
Genetic diseases
All the genetic diseases are not unnecessarily inherited. For example the chromosomal disorders are not inherited from generation to generation. They are a result of defects in the formation of gametes. Cancers are also genetic diseases but not inherited.
Cause
- Mutation (Genetic anomalies)
-> inherited
-> spontaneous (de novo)
These mutations have to be able survive in order to be transmitted to the next generation. In other words, the person with the mutation should be able to survive and reproduce.
- Chromosomal anomalies ( Numerical anomalies)
Always not inherited.
Mutations
- Can occur die to errors in DNA replication process.
- or due to UV light, Chemicals, Radiation.
Types of Mutations
Point mutations
Substitution of one nucleotide for another. Only one codon is changed. Outcome can vary. Three possible out comes are idetified
- Silent
Phenotype is the same. But there's a small difference in the base sequence. The change in the base sequence has not been able to make a difference in the Three dimensional structure and function. This results in gene polymorphisms (Slightly different gene, but the result is the same).
- non Sense
The change in the base sequence will add a termination codon infront of the real termination codon. This will result in premature termination of the amino acid sequence synthesis.
- Mis Sense
The change in one codon results in a change in the amino acid sequence (one amino acid). So there's a defective expression that leads to a disease.
ex: sickle cell anemia
Glutamic acid is replaced by a Valine Molecule, resulting in structural defect in the beta globine chain (change in the 6th codon of the beta globine chain).
Frame Shift Mutations
Deletion or an insertion of a nucleotide changing the reading frame.
ex:
AT[G] CGG ATC GAT - reading frame before the mutation
ATC GGA TCG AT - reading frame after the mutation
Below are some example diseases.
1. Some forms of Thalassaemia
2. Duchenne muscular dystrophy
3. polymorphisms in the angiotensine converting enzyme (DI, DD)
Inherited diseases
A disease inherited from parents (vertical transmission). But all the diseases inherited from parents are not genetic disorders.
Genetic diseases
All the genetic diseases are not unnecessarily inherited. For example the chromosomal disorders are not inherited from generation to generation. They are a result of defects in the formation of gametes. Cancers are also genetic diseases but not inherited.
Cause
- Mutation (Genetic anomalies)
-> inherited
-> spontaneous (de novo)
These mutations have to be able survive in order to be transmitted to the next generation. In other words, the person with the mutation should be able to survive and reproduce.
- Chromosomal anomalies ( Numerical anomalies)
Always not inherited.
Mutations
- Can occur die to errors in DNA replication process.
- or due to UV light, Chemicals, Radiation.
Types of Mutations
Point mutations
Substitution of one nucleotide for another. Only one codon is changed. Outcome can vary. Three possible out comes are idetified
- Silent
Phenotype is the same. But there's a small difference in the base sequence. The change in the base sequence has not been able to make a difference in the Three dimensional structure and function. This results in gene polymorphisms (Slightly different gene, but the result is the same).
- non Sense
The change in the base sequence will add a termination codon infront of the real termination codon. This will result in premature termination of the amino acid sequence synthesis.
- Mis Sense
The change in one codon results in a change in the amino acid sequence (one amino acid). So there's a defective expression that leads to a disease.
ex: sickle cell anemia
Glutamic acid is replaced by a Valine Molecule, resulting in structural defect in the beta globine chain (change in the 6th codon of the beta globine chain).
Frame Shift Mutations
Deletion or an insertion of a nucleotide changing the reading frame.
ex:
AT[G] CGG ATC GAT - reading frame before the mutation
ATC GGA TCG AT - reading frame after the mutation
Below are some example diseases.
1. Some forms of Thalassaemia
2. Duchenne muscular dystrophy
3. polymorphisms in the angiotensine converting enzyme (DI, DD)
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