lecture on genetic disorders

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  • diseases caused by an abnormality in an individual's DNA. Genetic Disorders

  • Human Genome

    46 chromosomes - 23 pairs: 22 pairs autosomal chromosomes or autosomes : 1 pair sex chromosomes male- x, y female- x, x

    approx 3 billion basepairs

    about 30,000 to 40,000 coding genes

  • Karyotype

    visual display of the chromosomes arranged by size, shape and banding pattern

  • Karyotype

    analysis of the chromosome make up of the individual. can determine if there are changes in the number or structure of the chromosomes. any change in the chromosome make up may indicate genetic disorder.

  • DiagnosisAmniocentesis involves drawing out the amniotic fluid surrounding the fetus through a small incision made on the mothers navel collected fluid contains cells from the fetus that can be analyzed



  • X and Y chromosomes

  • ATGAGTAACGCGTACTCATTGCGCAUGAGUAACGCGMet Ser Asn AlagenemRNAproteinTranscriptionTranslation

  • Genetic code1966Genetic code was discoveredScientists are now able to predict characteristics by studying DNA. This leads to genetic engineering, genetic counseling.

  • Types of mutationsChanges to the letters (A,C,T,G bases) in the DNApoint mutationchange to ONE letter (base) in the DNAmay cause change to protein, may notframeshift mutationaddition of a new letter (base) in the DNA sequencedeletion of a letter (base) in the DNAboth of these shift the DNA so it changes how the codons are readbig changes to protein!

  • Chromosomal mutations

  • result when a mutation causes the protein product of a single gene to be altered or missing.LEVEL 1: Single Gene Disorders

  • Sickle Cell Anemia a disorder that affects the red blood cells

    due to defect in gene found in chromosome 11 coding for beta subunit of hemoglobin

  • hemoglobin molecules don't form properly

    red blood cells are rigid, with a concave shape (like a sickle used to cut wheat)

    irregularly shaped cells get stuck in the blood vessels and are unable to transport oxygen effectively, causing pain and damage to the organs.

  • http://www.miracleofthebloodandheart.com/6_clip_image003.jpg

  • entire chromosomes, or large segments of them, are missing, duplicated, or otherwise altered.LEVEL 2: Chromosomal Abnormalities


  • http://www.ucl.ac.uk/~ucbhjow/bmsi/lec7_images/47_xx_21.gif

  • Down Syndrome

  • LEVEL 3: Multi-factorial DisorderThese disorders result in mutations in several genes, with interaction with the environment

  • Cancer

  • Cell cycle controlproteins called checkpoint proteins monitor progression through the cell cycle.

  • Benign tumors Grow slowly Remain in placeMalignant tumors (cancer)Weakened capacity for adhesionMetastasis

  • Cells break awayEnter blood vesselEmerge in new tissue


  • Down SyndromeTrisomy 21 karyotype 47,XX,+21

  • Cri-du Chat Syndrome46, 5p-

  • Turner Syndrome45,XO

  • Klinefelter Syndrome47, XXY

  • XYY SYNDROME47,XYYJacobs syndrome

  • XYY syndrome

    typically causes- no unusual physical features or medical problems.- Persons may be slightly taller than average, - have more severe acne than normal. -Skeletal malformations may also accompany - large hands and feet -Most males with XYY syndrome have normal sexual development and are able to conceive children.-Since there are no distinct physical characteristics, the condition usually is only detected during genetic analysis for other reasons.

    behavioral symptoms

    more likely to have behavior problems, possibly due to a higher testosterone

    XYY syndrome is not inherited, but usually occurs as a random event during the formation of sperm cells. An error in cell division called nondisjunction can result in sperm cells with an extra copy of the Y chromosome. The incidence of this condition is about one in 850 males.

  • Chromosome map


  • 1. Stay silent: ignore the genetic disorder and nothing gets fixed. 2. Try to treat the disorder with drugs or other approaches: depending on the disorder, treatment may or may not be a good long-term solution. 3. Put in a normal, functioning copy of the gene: if you can do this, it may solve the problem! ?

  • TreatmentCurrently available means of treatment of genetic disorders include alleviating or reducing the gravity of the symptoms of the genetic disorders such as medicine, replacement of damaged cells through stem cells and gene therapy.

  • Genetic DisorderCauses

    Manifestations(Symptoms)Mode of InheritancePossible Treatment1.