Mutations & Diseases

Nondisjunction: Missing 1 chromosome LETHAL! Results from non- disjunction –Chromosomes do not separate properly Miscarriage

Nondisjunction: More than 2 copies of chromosome SURVIVABLE! Results from non- disjunction (improper separation of chromosomes during meiosis) 3 copies of chromosome #21  trisomy Results in Down Syndrome Non-disjunction Karyotype

Non-disjunction: Turner Syndrome & Klinefelter’s Syndrome Turner Syndrome –Missing an X chromosome –Born with a webbed neck –Sterile Klinefelter’s Syndrome –Extra X chromosome –Reduced fertility

Other Mutations Type of MutationDefinitionWhat it looks like compared DeletionLetters erasedABC-EFGI TranslocationRearrangement of chromosomes to non-homologous chromosomes PQRS-GHI DuplicationCopiesABCABCDE-FGHI InversionFlipCBADEF-GHI Original: ABCDEF-GHI

DiseaseSymptomsDiagnosisCause Sickle Cell Anemia Blood clots, pain, infections, organ damage Abnormal hemoglobin 1 inherited recessive Tay-sachsCherry red spot on back of retina Test embryo prior to implantation Mutation on chromosome 15 Huntington’s Disease Mental deterioration, uncontrollable movements; middle age Protein found in brain cells Duplication of CAG codon Cystic Fibrosis Difficulty breathing, digestive issues High salt levels in sweat 3 base deletion PKULighter skin, hair Mental retardation Scanned at birth Recessive trait

Genetic Counseling Genetic counselors help people as they consider if they should be tested, when they receive results, and in the months after diagnosis –Help the family cope with a positive result –Arrange prevention and screening measures where they deem it appropriate

Pre-natal Testing for Genetic Disorders: Cont’d Karyotyping Lay out chromosomes –Check for correct # –Determine the sex of the baby

Pre-natal Testing for Genetic Disorders: Cont’d Ultrasound –Examine anatomical features of the fetus Amniocentesis –Needle into amniotic fluid –14-16 weeks Biochemical analysis –Enzymes & waste products

Pre-natal Testing for Genetic Disorders: Cont’d CVS (chorion villus sample) –Examine chromosomes within the chorion

Pre-natal Testing for Genetic Disorders Offspring have similar genetics to parents Family history- list of diseases of previous family members –8-10 weeks Pedigree- genetic chart based on family history

Square=maleCircle= female Vertical line & bracket connect parents to their children Unshaded indicates trait is not expressed (aa) Shaded indicates trait is expressed (could be AA or Aa) Horizontal line indicates marriage Each row of shapes represents a generation Oldest generation toward top