Genetic Aetiology of Human Disease

Genetic Aetiology of Human Disease: Understanding Variations in Human Genomes

• The triplet code, also known as a codon, is the basic unit of genetic information.
• The genetic code consists of 64 possible codons that code for 20 different amino acids and three stop signals.
• Mutations are the original source of genetic variation, and they can be somatic or germline.
• Dominant mutations require only one mutated allele to exhibit the disease phenotype, while recessive mutations require both alleles to carry the mutation to exhibit the disease phenotype.
• Mendelian diseases are caused by single mutations or genes and have a dichotomy or discontinuous presentation of phenotype, while complex diseases are caused by multiple variations across many genes and have a continuous and discontinuous presentation of phenotype.
• Mutations create a distinct phenotype, while polymorphisms contribute to normal variation within a population and are neither necessary nor sufficient for phenotype.
• Different types of variation include RFLPs, SNPs, minisatellites, and microsatellites, each with a different frequency, number of alleles, location, and detection method.
• Single base pair substitution, single nucleotide polymorphism, and mutations in regulatory sequences, RNA processing, and translation can affect the transcript and gene product.
• Deletion mutations in the Dystrophin gene cause Duchenne’s muscular dystrophy, while trinucleotide repeat disorders are caused by the expansion of trinucleotide repeats and can alter the expression/structure of a protein.
• Huntington's disease is an autosomal dominant disease caused by CAG repeats diseases at the 5' end of the Huntingtin gene, which leads to late onset neuronal loss.
• Complex diseases are still being studied to determine their genetic causes, which are likely to have subtle effects on gene function and are mostly in non-coding regions.
• Genome-wide association studies and sequencing can aid in determining the effects of polymorphisms, confirming their role in disease aetiology, and increasing our knowledge of how the genome is regulated to aid in drug development or therapeutic treatments.

Genetic Aetiology of Human Disease: Understanding Variations in Human Genomes

• The triplet code, also known as a codon, is the basic unit of genetic information.
• The genetic code consists of 64 possible codons that code for 20 different amino acids and three stop signals.
• Mutations are the original source of genetic variation, and they can be somatic or germline.
• Dominant mutations require only one mutated allele to exhibit the disease phenotype, while recessive mutations require both alleles to carry the mutation to exhibit the disease phenotype.
• Mendelian diseases are caused by single mutations or genes and have a dichotomy or discontinuous presentation of phenotype, while complex diseases are caused by multiple variations across many genes and have a continuous and discontinuous presentation of phenotype.
• Mutations create a distinct phenotype, while polymorphisms contribute to normal variation within a population and are neither necessary nor sufficient for phenotype.
• Different types of variation include RFLPs, SNPs, minisatellites, and microsatellites, each with a different frequency, number of alleles, location, and detection method.
• Single base pair substitution, single nucleotide polymorphism, and mutations in regulatory sequences, RNA processing, and translation can affect the transcript and gene product.
• Deletion mutations in the Dystrophin gene cause Duchenne’s muscular dystrophy, while trinucleotide repeat disorders are caused by the expansion of trinucleotide repeats and can alter the expression/structure of a protein.
• Huntington's disease is an autosomal dominant disease caused by CAG repeats diseases at the 5' end of the Huntingtin gene, which leads to late onset neuronal loss.
• Complex diseases are still being studied to determine their genetic causes, which are likely to have subtle effects on gene function and are mostly in non-coding regions.
• Genome-wide association studies and sequencing can aid in determining the effects of polymorphisms, confirming their role in disease aetiology, and increasing our knowledge of how the genome is regulated to aid in drug development or therapeutic treatments.