Human Genome

• Human Genome


  The complete set of genetic information present in humans

  
• Human Genome

  • Comprises all the DNA found in the 23 pairs of chromosomes in each human cell - 22 pairs of autosomes and one pair of sex chromosomes, X and Y, in males and two X chromosomes in females
  • The number of chromosomes in a cell is a characteristic of the species where it belongs

  
• Non-disjunction


  Chromosomes in Meiosis 1 or Meiosis 2 do not detach from each other at Anaphase I

  
• Down Syndrome (Trisomy 21)


  • Offspring has 47 chromosomes in cells instead of standard 46
  • Short neck
  • Small ears
  • Small mouth
  • Small stature
  • Flattened nose
  • Low muscle tone
  • Upward slanting eyes
  • Short hands and short fingers
  • Brushfield spots - or white spots on the colored part of the eye
• Cri-du-chat Syndrome


  • Small head size
  • Widely-spaced eyes
  • Round or moon-like face
  • High-pitched cat-like cry
  • Low weight at birth
  • Weak muscle tone during infancy
• Patau Syndrome (Trisomy 13 syndrome)


  • Cleft lip
  • Cleft palate
  • Heart defects
  • Weak muscle tone
  • Brain abnormalities
  • Extra fingers or toes
  • Eyes are poorly developed
• Klinefelter Syndrome (47, XXY syndrome)


  • Small testes
  • Breast enlargement
  • Decreased bone density
  • Decreased muscle mass
  • Unusually small penis or micropenis
  • Presence of few hair on the body and face
  • Infertile
• DNA (deoxyribonucleic acid)


  The molecule that carries the genetic instructions necessary for the growth, development, functioning, and reproduction of all known living organisms and many viruses
• Organization of the Human Genome

  • Organized into sequences of DNA that contain genes, which are the basic units of heredity
  • Genes provide the instructions for making proteins
  • Genes make up only a small portion of the entire genome, the rest consists of non-coding DNA sequences that regulate gene expression, control chromosome structure, and have other functions

  
• Genetic Variation


  • The human genome is largely the same across individuals, but there are small variations in the DNA sequence that make each person unique
  • These variations contribute to differences in traits such as appearance, susceptibility to diseases, and responses to medications
  • Some variations are inherited from parents, while others arise spontaneously due to mutations

  
• Genome Sequencing


  • The Human Genome Project (HGP), completed in 2003, was an international research effort that aimed to sequence and map all the genes in the human genome
  • This provided the first complete human genome sequence, which has since served as a reference for further studies
  • Advances in sequencing technologies have made genome sequencing faster and more affordable
• Countries involved in Human Genome Project (HGP)


  • United States
  • United Kingdom
  • France
  • Germany
  • Japan
  • Canada
  • China

  
• Medical Applications of the Human Genome

  • Genetic testing can identify individuals at risk for inherited diseases, inform treatment decisions, and guide the development of personalized medicine approaches
  • Genome-wide association studies (GWAS) help identify genetic variants associated with common diseases such as diabetes, cancer, and heart disease, providing insights into disease mechanisms and potential targets for therapy

  
• Ethical and Social Implications of the Human Genome

  • Concerns include privacy and security of genetic information, potential misuse of genetic data, discrimination based on genetic predispositions, and the implications of genetic engineering and gene editing technologies
  • Efforts to address these issues involve ongoing dialogue among scientists, policymakers, ethicists, and the public
• One copy of the human genome contains about 3 billion nucleotides, which are distributed among 23 chromosomes

  
• Most human cells have two copies of the human genome, with one copy inherited from each parent

  
• Diploid


  Cells containing two copies of each chromosome

  
• Single-Nucleotide Variants (SNVs)


  The smallest genomic variants, the most common type of genomic variation, reflecting a difference in a single nucleotide

  
• Single-Nucleotide Polymorphism (SNP)


  A subtype of SNVs that is present in at least 1% of the human population
• Insertions and Deletions (Indels)

  Another group of small genomic variants that reflect extra or missing DNA nucleotides in the genome, typically involving fewer than 50 nucleotides

  
• Tandem Repeats


  Short stretches of nucleotides that are repeated multiple times and are highly variable among people
• Structural Variants


  Large-scale genomic differences that involve at least 50 nucleotides and as many as thousands of nucleotides that have been inserted, deleted, inverted or moved from one part of the genome to another

  
• Copy-Number Variant (CNV)


  Genomic variation that involves a difference in the total number of nucleotides

  
• Epigenetic Variation


  Modifications to DNA that do not alter the underlying nucleotide sequence, but can influence behavior, morphology, and physiological phenotypes by affecting gene expression and protein synthesis

  
• Genomic Variants Detection


  • Specific DNA tests can determine whether a person has a particular genomic variant
  • Microarray can detect hundreds of thousands of SNVs at once
  • Genome sequencing is a more comprehensive way to detect genomic variants, including those that might not yet be known
  • Today, sequencing a human genome usually costs less than $1,000

  
• A typical human genome sequence contains ~5,000,000 SNVs, ~600,000 insertion/deletion variants, and ~25,000 structural variants

  
• Genome Variation


  • Genomic variation drives evolution and serves to expand biodiversity
  • Only a small fraction of genomic variants affects human health
  • Some genomic variants directly cause diseases, while others contribute to overall risk of conditions
  • Healthcare professionals are increasingly using information about patients' genomic variants to manage their medical care (genomic medicine)

  
• How many chromosome does Drosophila melanogaster ( Fruit Fly ) have?

  8
• How many chromosomes does Canis familiaris (Dog) have?

  78
• How many chromosomes does Homo sapien (Man) have?

  46
• How many chromosomes does Oryza sativa (Rice) have?

  24
• Cri-du-chat Syndrome

  
  

  The French for cat’s cry, is the sound of a baby having this condition when he/she cries. It is also known as 5p- (5p minus) syndrome and cat cry syndrome caused by DELETION whereby a part of the genetic segment in the small arm known as the p arm of chromosome 5 is missing.
• Patau Syndrome (Trisomy 13 syndrome)

  
  

  Each cell of the body has three copies of chromosome 13 instead of two which is the standard number.

  This results to an EXCESS OF GENETIC MATERIAL which bring disruptions to the normal development of the individual.
• Down syndrome (Trisomy 21)

  
  

  ✓During Meiosis I, chromosome pair 21 did not detach from each other at Anaphase I.

  ✓ The offspring has 47 chromosomes in his or her cells instead of the standard 46 chromosomes.

  ✓ excess chromosome
• Klinefelter Syndrome (47, XXY syndrome)

  
  

  ✓ Klinefelter syndrome hold an extra X chromosomes (XXY) or 47 chromosomes in their cells.

  ✓ This results to multiple genes in the X chromosomes.

  ✓ There is an occurrence of an extra X chromosomes in the cell among male individuals.