CHAPTER 3: GENETIC DISORDERS Flashcards
Genetic Imprinting
genes exhibit a “parent of origin” type of transmission (maternal v. paternal transmission)
DNA methylation v. acetylation
methylation=silence gene
acetylation=activate gene
Prader-Wili and Angelman
prader wili: deletion on PATERNAL chromosome
- short, fat
angelman: deletion on MATERNAL chromosome
- smiling, intellectual disability, seizures
Congenital Defects
birth defects in body structure, func, or metabolism
Marfan Syndrome
- autosomal DOMINANT
- defect in structural genes, long fingers
Penetrance v. Expressivity
penetrance: % of individuals that are affected
expressivity: all individuals have the disorder, but express at different levels
Autosomal Recessive Disorders
- PKU
- Tay Sachs
- Cystic Fibrosis
- Sickle cell anemia
Phenylketonuria (PKU)
- form of transmission
- effects
- treatment
- autosomal RECESSIVE
- phenylalanine accumulate in tissues/blood
- may lead to mental retardation, seizures
requires special diet to restrict phenylalanine intake
Tay Sachs Disease
- common in ashkenazi jews
- gangliosides accumulate in lysosome of nerve cells
- lead to blindness, deafness, paralysis, deterioration motor func
Cystic Fibrosis
- defect in CFTR gene
- defective transport of Cl-,result in thick secretions in lungs and GIT
- result in pulm infections or bronchitis
X Linked Recessive- DMD
Duchenne muscular dystrophy (DMD)
- muscle degeneration due to lack of protein
- caused by frameshift/nonsense deletions
X Linked Dominant- Fragile X syndrome
- inherited cause of intellectual/language disability
- fragile X gene on long arm of chr = FMR1
