genetic disorders

chromosomal mutations

includes

• abnormal chromosome number: non-disjunction

• alteration of chromosome structure

non-disjunction

homologous chromosomes pairs fail to separate during meiosis I or sister chromatids fail to separate during meiosis II

• bc errors with spindle fiber formation & attachment

  • abnormal number in the gamete that is formed & in the resulting zygote if it undergoes fertilization : aneuploidy

trisomy

chromosome is present in triplicate

polyploidy

when organisms have 2 or more complete sets of chromosomes

• occurs when normal gametes fuses with another in which there has been non-disjunction of all its chromosomes

  • results = triploid (extra entire set of chromosomes)

alterations of chromosome structure

include chromosomal deletions, inversions, translocations, duplications (since not at gene level can lead to dysfunction of many genes)

cystic fibrosis

recessive genetic disorder: CFTR gene is mutated

• results in high concentration of chloride — huge intake of water & causes mucus on cells to become sticky/thick —- leads to poor absobtion

phenylketomuria

recessive genetic disorder: PAH gene is mutated

• results in high levels of pheylalane

tay Sachs disease

recessive genetic disorder: HEXA gene is mutated

• results in beta-hexosamindase enzyme not functioning & a build up of GM2 gangleside which damages the central nervous system

sickle cell disease

recessive genetic disorder: HBB gene mutated

• hemoglobin shape is altered into sickle shape — red blood cells can be stuck together & lead to damage

achondroplasia

dominant genetic disorder: FGFR3 gene is mutated

• the codes for protein = overly active & messes with skeletal development & leads to disturbances in bone growth

huntingtons

dominant genetic disorder: HHT gene is mutated

• leads to repetition of CAG — produces mutated Huntington protein which forms toxic clumps in neurons (specifically the brain) which leads to cell death

hemophilia

sex-linked genetic disorder: F8 & F9 genes mutated

• hemophilia a: proteins for blood clotting are not made — prolonged bleeding

• hemophilia b: proteins for blood clotting are altered — prolonged bleeding

color blindness

sex-linked genetic disorder: OPN1LW & OPN1MW genes are mutated

• proteins that identify colors are mutated — leads to misidentification of colors

duchene’s muscular dystrophy

sex-linked genetic disorder: DMD gene is mutated

• leads to lack of dystrophin — leads to muscle cells breaking down & being replaced with fat + scar tissue

turner’s syndrome

chromosomal mutation: part of x or whole x chromosome is missing

• strictly affects women: includes underdevelopment (short, slow growth, no puberty)

aminocentesis

test to see if developing fetus has a serious recessive disease — fluid the baby bathes in is taken & tested for chromosomal defects

chorionic villus sampling (cvs)

test to see if developing fetus has a recessive disorder — takes part of placenta & tests for DNA alterations

epigenetics

studies how behaviors, environment & life experiences alter gene expression without altering DNA sequencing

• focuses on the factors lead to the turning on or off of genes (which is not a constant process)