Human Genetic Disorders Biology. Genetic Testing Amniocentesis and Chronic Villi Sampling Amniocentesis and Chronic Villi Sampling Sample of amniotic

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  • Human Genetic Disorders Biology
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  • Genetic Testing Amniocentesis and Chronic Villi Sampling Amniocentesis and Chronic Villi Sampling Sample of amniotic fluid or placenta Sample of amniotic fluid or placenta Karyotyping Karyotyping Taking a picture of the chromosomes in a cell Taking a picture of the chromosomes in a cell
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  • What Can Go Wrong? Nondisjunction (most deadly) Nondisjunction (most deadly) Improper separation of homologous chromosomes in meiosis I or chromatids in mieosis II or mitosis (at an early embryonic stage) Improper separation of homologous chromosomes in meiosis I or chromatids in mieosis II or mitosis (at an early embryonic stage) Results in too many or too few chromosomes in daughter cells Results in too many or too few chromosomes in daughter cells DNA mutations DNA mutations More specific letter-changes in code More specific letter-changes in code Results in the inability to make certain proteins Results in the inability to make certain proteins
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  • Nondisjunction Causes: Aneuploidy: cells that have too many or too few chromosomes are aneuploid. Aneuploidy: cells that have too many or too few chromosomes are aneuploid. Monosomy: only 1 of a pair present Monosomy: only 1 of a pair present Trisomy: 3 instead of 2 present Trisomy: 3 instead of 2 present
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  • Incidence of Genetic Abnormalities Maternal Age Maternal Age At 25 years, 17% of eggs may have chromosomal abnormalities. At 40 years, up to 74% may contain abnormalities. At 25 years, 17% of eggs may have chromosomal abnormalities. At 40 years, up to 74% may contain abnormalities. Spontaneous Abortion (Miscarriage) Spontaneous Abortion (Miscarriage) Two-thirds of all pregnancies are lost. These miscarriages are called spontaneous abortions. Two-thirds of all pregnancies are lost. These miscarriages are called spontaneous abortions. Genetic mutation causes an estimated 60% of these spontaneous abortions. Genetic mutation causes an estimated 60% of these spontaneous abortions.
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  • Family Pedigrees
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  • Down Syndrome Caused by Trisomy 21 Caused by Trisomy 21 Symptoms: Symptoms: Mental retardation Mental retardation Flattened face Flattened face Sparse, straight hair Sparse, straight hair Short stature Short stature High risk of cardiac anomalies, leukemia, cataracts, and digestive blockages High risk of cardiac anomalies, leukemia, cataracts, and digestive blockages Average life expectancy: 55 years (much longer than it used to be even just recently) Average life expectancy: 55 years (much longer than it used to be even just recently)
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  • Edward Syndrome Caused by Trisomy 18 Caused by Trisomy 18 Symptoms: Symptoms: Mental and physical retardation Mental and physical retardation Skull and facial abnormalities Skull and facial abnormalities Defects in all organ systems Defects in all organ systems Poor muscle tone Poor muscle tone Average life expectancy: 2-4 months Average life expectancy: 2-4 months
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  • Patau Syndrome Caused by Trisomy 13 Caused by Trisomy 13 Symptoms: Symptoms: Mental and physical retardation Mental and physical retardation Skull and facial abnormalities Skull and facial abnormalities Defects in all organ systems Defects in all organ systems Cleft lip & large triangular nose Cleft lip & large triangular nose Extra digits Extra digits Average life expectancy: 6 months (but die in the first month) Average life expectancy: 6 months (but die in the first month)
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  • Sex Chromosome Abnormalities Turners Syndrome (X0 - female) Turners Syndrome (X0 - female) 1 in 2000 1 in 2000 Infertile, sexually underdeveloped, short stature, narrow aorta, normal intelligence Infertile, sexually underdeveloped, short stature, narrow aorta, normal intelligence Klinefelter Syndrome (XXY - male) Klinefelter Syndrome (XXY - male) 1 in 1000 1 in 1000 Reduced sexual maturity, secondary sexual characteristics (breast swelling), no sperm production Reduced sexual maturity, secondary sexual characteristics (breast swelling), no sperm production
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  • Triple X Syndrome (XXX female) Triple X Syndrome (XXX female) 1 in 1500 1 in 1500 Slight IQ reduction, menstrual irregularities Slight IQ reduction, menstrual irregularities Jacob Syndrome (XYY male) Jacob Syndrome (XYY male) Incidence unknown (lack of diagnosis) Incidence unknown (lack of diagnosis) Tall, acne issues, speech/reading problems Tall, acne issues, speech/reading problems Disproportionate number incarcerated Disproportionate number incarcerated 96% are normal (most dont realize they have this condition) 96% are normal (most dont realize they have this condition) Sex Chromosome Abnormalities
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  • DNA Mutations Cri du Chat Syndrome (cry of the cat) Cri du Chat Syndrome (cry of the cat) Deletion on part of chromosome 5 Deletion on part of chromosome 5 Fragile X Fragile X Repeated sequences of CCG on X chromosome Repeated sequences of CCG on X chromosome Normal = 6-50 copies Normal = 6-50 copies Carrier (males) = 50-230 copies Carrier (males) = 50-230 copies Disorder = more than 230 copies Disorder = more than 230 copies Causes mental retardation (2 nd behind only Down Syndrome) Causes mental retardation (2 nd behind only Down Syndrome)
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  • Autosomal Recessive Disorders Cystic Fibrosis (CF) Cystic Fibrosis (CF) Mutation on chromosome 7 Mutation on chromosome 7 Thick mucous develops in lungs and digestive tract Thick mucous develops in lungs and digestive tract Difficulty breathing & lung infections Difficulty breathing & lung infections Most common lethal genetic disorder Most common lethal genetic disorder 1 in 25 is a carrier 1 in 25 is a carrier 1 in 2500 has disorder 1 in 2500 has disorder
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  • More Autosomal Recessive Tay Sachs Disease Tay Sachs Disease Fatty substance builds up in neurons Fatty substance builds up in neurons Gradual paralysis and loss of nervous function by age 4-5 Gradual paralysis and loss of nervous function by age 4-5 Single defective enzyme Single defective enzyme Heterozygote carriers (Hh) do not have disorder, but are resistant to Tuberculosis Heterozygote carriers (Hh) do not have disorder, but are resistant to Tuberculosis Especially common in Jewish population (central and eastern European descent), up to 11% are carriers Especially common in Jewish population (central and eastern European descent), up to 11% are carriers
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  • More Autosomal Recessive PKU (Phenylketonuria) PKU (Phenylketonuria) Cant break down amino acid phenylalanine (missing critical enzyme) Cant break down amino acid phenylalanine (missing critical enzyme) Phenylalanine builds up and interferes with nervous system leading to mental retardation and even death Phenylalanine builds up and interferes with nervous system leading to mental retardation and even death Early screening phenylalanine restricted diet for children with disorder Early screening phenylalanine restricted diet for children with disorder
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  • Sickle-Cell Anemia Sickle-Cell Anemia Abnormality in hemoglobin (carries oxygen in our red blood cells) Abnormality in hemoglobin (carries oxygen in our red blood cells) Cells become sickle-shaped and clog blood vessels (painful) Cells become sickle-shaped and clog blood vessels (painful) Causes poor circulation, jaundice, anemia, and hemorrhaging Causes poor circulation, jaundice, anemia, and hemorrhaging Heterozygote carriers (Hh) do not have disorder and are resistant to malaria Heterozygote carriers (Hh) do not have disorder and are resistant to malaria 8-10% of Africans (or descendants) are carriers 8-10% of Africans (or descendants) are carriers More Autosomal Recessive
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  • Sickle-Cell Anemia Photo
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  • Autosomal Dominant Disorders Neurofibromatosis (NF) Neurofibromatosis (NF) Could be Elephant Mans disorder Could be Elephant Mans disorder As mild as tan spots on skin As mild as tan spots on skin Could cause severe deformities, tumors, even death Could cause severe deformities, tumors, even death 1 in 3000 newborns 1 in 3000 newborns Mutation on chromosome 17 Mutation on chromosome 17
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  • Huntingtons Disease Huntingtons Disease Brain cells degenerate, causing involuntary muscle jerks, slurred speach, loss of balance, mood swings, memory loss, incapacitation Brain cells degenerate, causing involuntary muscle jerks, slurred speach, loss of balance, mood swings, memory loss, incapacitation Progressive: eventually causes death Progressive: eventually causes death Onset: 35-45 years old Onset: 35-45 years old Repeated sequences of AGC on chromosome 4 Repeated sequences of AGC on chromosome 4 Diagnostic test available, but no cure Diagnostic test available, but no cure Would you want to know? Would you want to know? Autosomal Dominant Disorders
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  • X-Linked or Sex-Linked Traits Traits located on X Chromosome Traits located on X Chromosome Males have them more often than females Males have them more often than females They only have one X chromosome They only have one X chromosome
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  • Colorblindness (3 types Red/Green most common) Colorblindness (3 types Red/Green most common) X-Linked or Sex-Linked Traits
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  • Hemophilia Hemophilia 1 in 1500 males 1 in 1500 males Lack a blood clotting factor Lack a blood clotting fact