GENETICS inheritance pptx...............

genetic inheritance

1. Inheritance By WALEED KHAN

2. Types of Inheretance This presentation discuss the various types of inheritance from: Dominant-recessive inheritance through Polygene inheritance

3. Inheritance patterns What do they do? They trace the transmission of genetically encoded traits, conditions or diseases to offspring. Several modes of inheritance: -Single Gene ( Mendelian ) - Multifactorial -Mitochondrial

4. Punnett Squares Used to figure out for single gene inheritance the possible gene combinations that can result from mating 2 parents with of known genotypes. Traits w/dominant alleles include: Freckles Dimples Widow’s peaks

5. Single Gene Inheritance Definition: A type of genetic disease caused by mutation in DNA sequence of 1 gene that alters the protein. Types of Single Gene Inheritance: Autosomal : it’s the gene responsible for the phenotype that is located on 1 of 22 pairs of autosomes (non-sex determining chromosomes) X-linked: the gene that encodes for the trait which is located on an X chromosome Dominant: conditions that occur in heterozygotes , persons with only 1 copy of a mutant allele Recessive: conditions only occur in persons who have > 2 copies of a mutant allele (homozygous).

6. Autosomal Dominant Definition: Autosomal dominant disorders are generally transmitted from parent to child through one or more generations or can result from a new mutation. The disease will typically shows a “ Mendelian pattern” of inheritance -Males & females are equally affected Examples: - Albinism - acondroplasia (short-limbed dwarfism) -Huntington's disease - polycystic kidney disease -deafness

7. Autosomal Recessive Affected children have parents that possess both a mutant & functioning copy of the allele (affected) Autosomal recessive diseases : -Cystic fibrosis -Sickle cell anemia - Tay -Sachs

8. Sex-Linked Inheritance Definition : These are inherited traits that are determined on the genes of the sex chromosomes (X and Y) Y : gene that determines maleness -is physically smaller -carries only 78 genes -codes for clotting factors -codes for cone pigments -certain alleles expressed X : is physically larger -carries over 2,500 genes -contains many proteins that code for brain function X-linked traits gen. passed from mom to son Females must have (2) X linked recessive alleles to exhibit a specific disorder

9. X-Linked Recessive X-linked Recessive Disorders : • Duchenne muscular dystrophy • hemophilia A • X-linked severe combined immune disorder (SCID) • some forms of congenital deafness Sex-linked genetic diseases : - Duchenne muscular dystrophy -Hemophilia -red/green colorblindness -rarely seen in females

10. X-Linked Dominant Inheritance Definition: a gene that is located on an X chromosome, that causes no transmission from father to son, but occurs from father to daughter (as all daughters will be affected since father has (1) X chromosome to give. Children of an affected mom have a 50% chance of inheriting the X chromosome with the mutant allele X-linked dominant disorders clinically occur when (1)copy of the mutant allele is present.

11. X-Linked Traits and Mutations X-Linked Recessive X-Linked Dominant Mom: CARRIER , Dad: noncarrier Each daughter: 25% noncarrier 25% carrier Each son: 25% noncarrier 25% affected Mom: noncarrier dad: affected Each daughter: 100% carrier Each son: 100% noncarrier Mom: affected dad: noncarrier Each daughter or son: 50% affected 50% nonaffected Mom: noncarrier dad: affected Each daughter: 100% affected Each son: 100% nonaffected http://www.beltina.org/health-dictionary/inheritance-patterns-autosomal-traits-x-linked-mutation.html

12. http://cw.tufts.edu

13. Incomplete Dominance Definition: where the heterozygote has a phenotype intermediate between those of homozygous dominant and homozygous recessive persons. - Typically uncommon in humans. Examples: sickle-cell anemia,Hemoglobin SS disease ( Hb SS) or Sickle cell disease Note: persons heterozygous for the sickling gene (Ss) have sickle cell trait, causing them to make normal and abnormal sickling hemoglobin.

14. Autosomal Traits & Mutations Autosomal Recessive Autosomal Dominant Both Parents are Carriers 1 parent carrier, 1 parent not carrier Each child: - 25% condition - 25% noncarrier - 50% carrier Each child: - 50% noncarrier - 50% carrier Both parents affected 1 parent affected, 1 parent unaffected Each child: - 25% unaffected - 25% more severely affected - than parents - 50% affected Each child: - 50% unaffected - 50% affected

15. Polygene Inheritance

16. Polygene Inheritance Definition: where many phenotypes rely upon several alternate gene pairs that can occur simultaneously and at different locations on a gene. Causes: -continuous phenotypic variation or -quantitative phenotypic variations Note: this is the reason there is such extremes in characteristics Examples: skin color, metabolic rate, height variations, & intelligence (skin color alone relies upon 3 separate, inherited genes : A,a , B,b , C,c )

17. Polygenetic Inheritance… http://wikispaces.psu.edu

18. Multiple Allele Inheritance Definition: where although we inherit just (2) alleles for every gene, genes can exhibit more than (2) allele forms which causes multifactorial inheritance. Example: blood types that determine ABO compatibility (expressed I A , I B , and i ) IA and IB are codominant and “ i ” is recessive to them

19. Mul tifactorial Inheritance Definition: where many diseases have multifactorial inheritance patterns -these conditions result from many genetic &environmental factors. -are not genetically determined, but result from mutations that predispose persons to a specific disease -additional genetic & environmental factors can influence the disease developing Genetic heterogeneity -many genetic alterations will influence a person acquiring a specific disease Example: CAD risk factors include hyperlipidemia, diabetes, & high blood pressure -those risk factors have genetic & environmental pieces Note: this is why multifactorial inheritance is more complex than Mendelian inheritance and WHY its difficult to trace via pedigree

20. Multifactorial Inheritance… Common Multifactorial Conditions: • Alzheimers disease • heart disease • insulin-dependent diabetes mellitus • intelligence • some cancers • neural tube defects •schizophrenia Example: A family pedigree from a BRCA1 gene mutation. Here a father can be a carrier & pass the gene along to a child. Because not all people who acquire the gene develop the disease, its difficult to trace the transmission. http://www.uvm.edu/~cgep/Education/Inheritance2.html

21. Mitochondrial Inheritance Definition: many diseases are transmitted by mitochondrial inheritance affecting organs with high-energy use ( ie . heart, kidneys, skeletal muscle, & liver. -This kind of inheritance occurs as a result of transmission from a mom to a child, so all children will inherit this but not all will necessarily be affected. Note: Mitochondria are organelles in the cell cytoplasm. -they make multiple copies of a circular chromosome. -their main function is to convert molecules into usable energy. This is the least common pattern of inheritance

22. References http://www.beltina.org/health-dictionary/inheritance-patterns-autosomal-traits-x-linked-mutation.html https://www.biologis.com/pgs/benefit/carrier-status http://cw.tufts.edu http://geneticalliance.org.uk http://www.uvm.edu/~cgep/Education/Inheritance2.html http://mdmedicine.wordpress.com/2011/04/07/types-of-inheritance/ http://wikispaces.psu.edu

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