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Homozygous recessive females may be affected

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-Homozygous recessive females may be affected -Inheritance may appear to “skip generations” Examples: Duchene muscular dystrophy, and classic hemophilia X-Linked Dominant Disorder -Heterozygous males and females affected -Reduced penetrance in females -Fragile X syndrome is an example -Most common genetic cause of cognitive disorders -Effects are variable and related to extent of mutation of the allele Down Syndrome: A common chromosomal abnormality (trisomy 21) and may be due to non-disjunction or translocation. Risk increases with mothers over 35 years old. Signs and symptoms: distinctive facial features with small open mouth with protruding tongue and high arched palate. Small head with flat face, slanted eyes and brushfield spots on irises. Short statute with hypotonic muscles, loose joints, developmental delays and mental retardation. Various congenial abnormalities may also be present. Chromosomal Disorders Turner’s Syndrome: affects females, short stature, and infertility Klinefelter Syndrome XXY: Extra X chromosomes present, and infertility Multifactorial Disorders: Genetic influences combined with environmental factors Ex: cleft palate, congenial hip dislocation, congenial heart disease, and type 2 diabetes Developmental Disorders: Exposure to drugs, chemicals, or radiation during childbearing years -TORCH: acronym for routine prenatal screenings that test for high-risk maternal infections T: toxoplasmosis O: other (hepatitis B, mumps, rubella, varicella, gonorrhea,) R: rubella C: cytomegalovirus H: herpes simplex virus type 2 -Exposure to known teratogens in the first 2 months of development. This can impair organogenesis Diagnostic Tools: testing may be available prior to conception, first trimester, or newborns Testing is recommended for : family history, birth to child with abnormalities, high risk for specific diseases, and older than 35 Blood test of pregnant women : alpha-fetoprotein testing In Utero testing : amniocentesis and chronic villus assay Neonatal testing : blood testing and excreted metabolites ex: PKU Genetic Engineering -Isolating, copying, and transplanting genes- we can do this in microorganisms,
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plants, animals, and humans. Used in agriculture to produce transgenic or genetically modified foods Ultimate goal: insert normally function allele to prevent disease -Technically possible but clinical trials have no been uniformly successful Gene Therapy: identifies gene and protein responsible for condition, determines how gene expression is controlled, produces drug that will inhibit gene expression, and research is focused on cancer growth promoters that have resulted in such drugs Genetic screening and DNA testing -Screening at risk population for the specific allele: however this is costly and concerns regarding privacy and access issues -DNA testing to identify individuals for paternity or forensic purposes -Legislations has been drafted in the US to protect the genetic rights of individuals such as health care, employment, and insurance Chapter 8: Adolescence Diseases
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Homozygous recessive females may be affected Inheritance...

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