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What are the primary causes of congenital defects?
- Genetic factors
- Environmental factors during embryonic development
- Affect a quarter of a million infants in US each year, leading cause of infant death
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Single gene disorders are caused by a mutant allele, which may be present on either an ____ or the X-or-Y _____ ______.
autosome, or "sex" chromosome
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True/False: A single mutant allele from an affected parent is transmitted to an offspring, depending on the gender of the offspring.
False. Single mutant allele can affect both genders equally
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Marfan Syndrome Characteristics:
- 75% family origin 25% new mutations
- 1 in 20,000 people
- Makes abnormal connective tissue: eyes, heart and blood vessels, skeletal system
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Huntington's Disease is an autosomal (dominant/recessive) disorder. List the traits:
- Dominant
- Causes brain neurons to degenerate
- Affects: movement, cognition, and causes psychiatric disorders: dementia, aggressiveness, social withdrawal, mistaken for chronic alcoholism
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Cystic fibrosis:
- Autosomal recessive disorder
- most common life-threatening genetic disorder in Caucasians (1/25 US Citizens)
- Abnormal Cl- Transported across epithelium: affects respiratory tract, GI tract, Reproductive tract
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Sickle Cell Disease is an autosomal (Dominant/recessive) disorder that...
- Recessive
- is an abnormal hemoglobin in RBC
- chronic hemolytic anemia and blood vessel occlusion
- No cure
- Occurs most in persons of African descent because mutant allele is protective against malaria
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Phenylketonuria (PKU) is autosomal (dominate/recessive) disorder. Describe:
- Recessive
- 1 in 10,000 people
- Excess phenylalanine cause brain damage
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Tay-Sachs Disease is autosomal (dominate/recessive) disorder. Explaine:
- recessive
- Predominately in Eastern European Jews
- Excess ganglioside in lysosome damage brain neurons and retina
- deterioration of motor and menatl function
- seziures
- blindness
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X-linked recessive disorders affect which gender most?
Males
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Hemophilla A
- Abnormal coagulation causes bleeding in the soft tissues, GI tract, hip, knee, elbow, and ankle joints
- Seen more in males -X chromosome
- From Queen Victoria
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Name two common CONGENITAL Multifactorial inheritance disorders
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What are some adult multifactorial inheritance disorders? (More often due to genetics and environment)
- Coronary artery disease
- Diabetes mellitus
- Hypertension
- Cancer (some forms)
- Bipolar disorder and schizophernia
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Structural Chromosomal Disorder: Cri Du Chat ("cry of cat") syndrome
- Deletion of segment from chromosome #5
- Small head and unusual features
- Mewing sound present in newborn
- Children have feeding problems
- Often die in infancy
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Aneuploidy
- zygote that has an abnormal chromosome number
- results in spontaneous abortions
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Polysomy individuals:
- have more than two of one type of chromosome
- XXY or XXXY
- Klinefelter syndrome
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Trisomy individuals:
- Have one extra chromosome for one type of chromosome
- extra number 21 chromosome
- Down's syndrome
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Monosomy individual:
- only one chromosome (not a pair) for one type of chromosome
- One less X chromosome
- Turner's Syndrome
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Klinefelter Syndrome
- Male born with more than one X chromosome
- Small testes and inability to produce sperm
- Low testosterone levels during puberty
- 1 in 500 to 1 in 1000 male births
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Turner's Syndrome:
- Female born with only one X chromosome
- Short in stature
- webbing of neck
- absence of ovaries, no menstruation
- visuospatial organization
- attention deficit problems
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What is the most common chromosomal disorder?
A. Down's syndrome
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True/False: Risk of down syndrome increases with the age of the mother
- True
- 1 in 25 if mother is over 45
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Down Syndrome
- aka Trisomy 21
- Short stature
- Small square head
- Epicanthal fold of eyes
- Slanted eyes
- Mental retardation
- Heart defects
- Prone to Alzheimer's
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What are some known causes of congenital disorders or malformations?
- Diabetes melitus
- smoking
- Alcohol
- Measles and rubella viruses
- Taxoplasma gondii
- Radiation
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What is a teratogenic agent?
An environmental agent that produces abnormalities during embryonic or fetal development
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What are some teratogenic agents?
- Radiation
- Chemicals and drugs: alcohol-fetal syndrome, anticoagulants(warfarin), Cancer drugs(aminopterin, methotrexate)
- Infectious agents: viruses, bacteria, protistans
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Fetal Alcohol Syndrome (FAS)
- Harmful effects extend throughout pregnancy
- Changes facial features, growth deficits, CNS abnormalities
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