Lecture 5 Dentistry Genetics PDF

LECTURE 5 GENERAL BIOLOGY CODE: BAS131 FIRST YEAR DR WESAM SALAMA FIRST SEMESTAR 2024-2025 MUTATION Classification of mutation A.BASED ON SURVIVAL  1. Lethal mutation: when the mutation causes death to all individuals  2. Sub-lethal mu...

LECTURE 5 GENERAL BIOLOGY CODE: BAS131 FIRST YEAR DR WESAM SALAMA FIRST SEMESTAR 2024-2025 MUTATION Classification of mutation A.BASED ON SURVIVAL  1. Lethal mutation: when the mutation causes death to all individuals  2. Sub-lethal mutation: when the mutation causes 90% death to individuals  3. Sub-vital mutation: when the mutation causes less than 90% death to individuals  4. Vital mutation: when the mutation dos not affect the survival to individuals  5. Super-vital mutation: when the mutation enhance the survival of an individual.  B.BASED ON CAUSES OF MUTATION  1. Spontaneous mutation  Spontaneous mutation occurs naturally without any cause.  The rate of spontaneous mutation is very slow (Methylation followed by deamination of cytosine).  Rate of spontaneous mutation is higher in eukaryotes than prokaryotes. (UV light of sunlight causing mutation in bacteria )  2. Induced Mutation  Mutations produced due to treatment with either a chemical or physical agent  The agents capable of inducing such mutations are known as mutagen. use of induced mutation for crop improvement program is known as mutation breeding.  C.BASED ON THE ORIGIN TISSUE  1. Somatic mutation  A mutation occurring in somatic cell is called somatic mutation.  In asexually reproducing species somatic mutations transmits from one progeny to the next progeny  2. Germinal Mutation  When mutation occur in gametic cells or reproductive cells  In sexually reproductive species only germinal mutation are transmitted to the next generation  Types of mutation Mutation or change in: 1-Chromosomes (number or structure) 2-DNA or nucleotides sequence 3-Gene mutation 4- Protein structure CHROMOSOMAL MUTATION OR ABNORMALITY (ABERRATION)  Chromosome mutation Numerical mutation (change in chromosomes number) Structural mutation (change in their structure) Abnormality in sex chromosomes NUMERICAL chromosome MUTATION What are numerical chromosome abnormalities? Numerical abnormalities are a type of chromosome defect. These types of birth defects occur when there is a different number of chromosomes in the cells of the body from what is usually found. So, instead of the typical 46 chromosomes in each cell of the body, there may be 45 or 47 chromosomes. What is the meaning of: Monosomy Trisomy Tertrasomy  DOWN SYNDROME (TRISOMY 21) Numerical PATAU SYNDROME (TRISOMY 13) Mutation EDWARD SYNDROME (TRISOMY 18) PALLISTIR KILLIAN SYNDROME (TETRASOMY 12, ISOCHROMOSOME) KLIENFILTER SYNDROME (XXY, EXTRA X CHROMOSOME) TURNER SYNDROME (SINGLE X CHROMOSOME)------MONOSOMY DOUBLE Y CHROMOSOME (XYY, EXTRA Y CHROMOSOME) STRUCTURAL MUTATION What is a structural chromosome abnormality? Structural abnormalities are when part of an individual chromosome is missing, extra, switched to another chromosome, or turned upside down. Chromosomal abnormalities can occur as an accident when the egg or the sperm is formed or during the early developmental stages of the fetus.  TYPES OF STRUCTURAL CHROMOSOME MUTATIONS. DELETIONS: INVOLVE THE LOSS OF PART OF A CHROMOSOME DUPLICATIONS: PRODUCE EXTRA COPIES OF PART OF A CHROMOSOME INVERSIONS: REVERSE THE DIRECTION OF PARTS OF CHROMOSOMES Structural mutation TRANSLOCATIONS: OCCUR WHEN PART OF A CHROMOSOME BREAK OFF AND ATTACH TO ANOTHER CHROMOSOME ISOCHROMOSOME: UNBALANCED STRUCTURE STRUCTURAL ABNORMALITY IN WHICH THE ARMS OF THE CHROMOSOME ARE MIRROR IMAGES OF EACH OTHER  RINGS: A loss of both ends a chromosome , the remaining part rejoin to form a circle or ring. NON-DISJUNCTION: Failure of chromosomes to separate during meiosis Causes gamete to have too many or too few chromosomes Disorders: – Down Syndrome-Turner Syndrome –– Klinefelter’s Syndrome –  Mosaicism is a condition in which cells within the same person have a different genetic makeup. This condition can affect any type of cell, including: Blood cells, Egg and sperm cells, Skin cells SYNDROME ASSOCIATED WITH STRUCTURAL CHROMOSOME MUTATION Williams syndrome Pradar willi syndrome Angelman syndrome (happy pubbet) Cri-du chat syndrome Williams syndrome Deletion of a small piece of chromosome 7. Williams Syndrome (WS) is a rare genetic disorder characterized by: 1. Mild to moderate delays in cognitive development or learning difficulties. 2. A distinctive facial appearance.  Facial appearance: puffiness around the eyes A short nose with a broad nasal tip wide mouth full cheeks full lips, and a small chin. People with WS are also likely to have a long neck, sloping shoulders, short stature, limited mobility in their joints, and curvature of the spine. Some individuals with WS have a star-like pattern in the iris of their eyes. Cardiovascular dysfunction ADHD. PHOBIC Oral manifestations: 1. Smaller teeth and open mouth 2. Outward inclination of maxillary teeth. 3. A high prevalence of dental caries. 4. Malocclusion PRADER WILLI syndrome Deletion in chromosome 15 (parental) Prader-Willi (PRAH-dur VIL-e) syndrome is a rare genetic disorder that results in a number of physical, mental and behavioral problems. A key feature of Prader-Willi syndrome is a constant sense of hunger that usually begins at about 2 years of age. Oral manifestations: 1-Dental caries. 2. Enamel weakness. 3. Decreased salivation viscous, bubbly saliva. 4. Gingivitis ANGLEMAN syndrome Most cases of Angleman syndrome are caused by the child not getting a copy of the UBE3A gene from his mother, or the gene not working. This means there's no active copy of the gene in the child's brain. SYMPTOMS A child with Angleman syndrome will begin to show signs of delayed development at around 6 to 12 months of age, such as being unable to sit. Frequent laughter and smiling. Hyperactive Skin, hair and eyes that are paler than other family members. Tendency to stick the tongue out. Oral manifestations: Wide mouth with wide space between teeth. 2. Frequent drolling. 3. Swallowing disorder. CRI-DU CHAT syndrome (5P deletion syndrome) Deletion or missing of part in chromosome 5. Called cat cry syndrome. The children have a sound of cat on crying. Intellectual disability Small head (microcephaly) Low birth weight Weak muscles Oral manifestation Oral features : micrognathia malocclusions high but rarely cleft palate anterior open bite poor oral hygiene enamel hypoplasia chronic periodontitis.  ‫)‪ASSIGNMENT 3 (5 MARKS‬‬ ‫‪ WRITE A SHORT ESSAY ABOUT A SYNDROME ASSOCIATED WITH‬‬ ‫‪STRUCTURAL CHROMOSOME MUTATION‬‬ ‫اكتب مقاالً مختصرا ً عن أي متالزمة مصاحبة للطفرة الكرموسومية الناتجه عن تأثير ‬ ‫التغيير في التركيب للكروموسوم‬