Genetic Disorders Unit 5

What is a Karotype? A picture of the collection of chromosomes found in an individual’s cells Tells you the chromosome number of an organism 46 in humans Tells you the sex of an organism XX = Female XY = Male Can indicate whether or not a chromosomal abnormality is present.

Karyotype MALE FEMALE

Chromosomal Mutations Inversion A segment of a chromosome breaks off, flips, and reattaches Duplication An entire gene segment is repeated Non Disjunction Caused by the failure of chromosomes separating during meiosis Typically classified as either monosomy or trisomy. Translocation When a section of one chromosome attaches to another chromosome Deletion When a section of a chromosome is deleted

Common Chromosomal Abnormalities Monosomy Trisomy the condition in which a diploid cell is missing a chromosome the condition in which a diploid cell has an extra chromosome

Down Syndrome Down Syndrome/Trisomy 21 Extra 21st Chromosome Trisomy /Normally a non disjunction, can be a translocation. Symptoms: Distinctive shaped eyes Cognitive heart abnormalities Simian folds Below average cognitive ability

Down Syndrome Down’s caused by a translocation. Down’s caused by a non disjunction

Turner’s Syndrome 1 X chromosome and no match (XO) Monosomy Turner’s Symdrome 1 X chromosome and no match (XO) Monosomy Only females Symptoms Short stature, Webbed neck, Broad chest, Non-functioning ovaries, sterility

Klienfelter’s Syndrome 2 X chromosomes and 1 Y Trisomy (XXY) Only in males Symptoms Underdeveloped male sex characteristics Reduced fertility Slightly feminime characteristics Potential language impariment

Edward’s Syndrome Edward’s Syndrome/Trisomy 18 Caused by non-disjunction (trisomy)of the 18th chromosome. Symptoms: Clenched hands Feet with a rounded bottom Low birth weight Mental delay Poorly developed fingernails Small head (microcephaly)

Cri du chat Cri du chat Also called “call of the cat”, chromosome 5p deletion syndrome or Lejeune’s syndrome. Caused by a deletion of part of chromosome 5 1:50,000 live births, slightly more common in girls. Symptoms: Cognitive delays, unique facial features, unique cry

Common Gene Mutation Not detectable on a karyotype Sickle Cell Anemia Tay-Sachs Disease Cystic Fibrosis

Sickle Cell Anemia Sickle Cell Caused by a point mutation within the protein that makes hemoglobin. Thought to have evolved as a defense against malaria Symptoms: Anemia, Fatigue, Infection

Tay Sachs Disease Tay Sachs Disease Point mutation causing the body to lack a critical protein that breaks down chemicals in nerve tissue Symptoms Deafness, Blindness, Seizures, Demintia No treatments Children usually die before age 5

Cystic Fibrosis Cystic Fibrosis Most common mutation is a deletion (frame shift mutation) of 3 nucleotides on chromosome 7 resulting in the loss of the amino acid phenylalanine Symptoms Thick mucus secretions, and frequent chest infections, trouble digesting food.