Precision Medicine PDF

2. Precision medicine 2.1. Human genome 2.1.1. Human genetic information Human Genome Project ○ Published in 2003 ○ First complete human genome ○ 3 billion base p...

2. Precision medicine 2.1. Human genome 2.1.1. Human genetic information Human Genome Project ○ Published in 2003 ○ First complete human genome ○ 3 billion base pairs – 2 m from end to end but compacted in a cell nucleus (15 um) Chromosomes ○ Base pairs → Histones → Chromosomes ○ P arm: shorter ○ Q arm: longer ○ Telomere: ends of chromosome ○ Centromere: between P and Q arms of chromosome ○ Telomeres & centromeres have highly repetitive DNA sequences Human genome ○ Diploid (46 chromosomes): ○ 22 autosomes (x2) ○ 2 allosomes (sex chromosomes) Structure of a gene: ○ 1.2% of our genome: coding regions ○ ~ 20,000 coding genes ○ Divided into exons, introns, gene regulatory elements (promoters, enhancers) Properties ○ Organised, usable (regulated and expressed), stable, and copied accurately to the next generation of cells 2.1.2. Genetic variation Describes the difference in DNA among individuals or cells Account for most phenotypes that are observed Includes most diseases and health conditions in humans, e.g. height, susceptibility to diseases Interaction with the environment is also a major contribution to phenotype A. Copy number variation Gain or loss of whole chromosome or whole arms of chromosomes  E.g. Downs syndrome ○ Extra copy of chromosome 13 B. Structural variation A portion of chromosomes affected ○ Deletion ○ Duplication ○ Inversion ○ Translocation E.g. Facioscapulohumeral Muscular Dystrophy (FSHD) ○ Deletion of a portion of chromosome 4 (repeating units of a piece of 30 kilobase DNA (D4Z4) ) Healthy: 11-100 copies of D4Z4 repeats FSHD: