Genetic Disorders U.2 L.4

genetic disorder : disease caused by a genetic mutation

genetic disorder causes : germline mutations (change in DNA sequence), and chromosomal mutations (non-disjunction even in meiosis)

gene mutations could be caused by mutagens (UV light, radiation, etc..)

Good, Bad and benign mutations

patterns of inheritance : Autosomal dominant, Autosomal recessive, sex linked recessive, codominant

Autosomal dom : dominant gene on a non sex chromosome (ex. huntington disease)

Autosomal rec : recessive gene on a non-sex chromosome (ex. cystic fibrosis)

sex linked recessive : recessive gene on the X-chromosome (ex. hemophilia)

codominant : codominant gene on a non-sex chromosome (ex. sickle cell anemia)

chromosomal mutation is caused by non-disjunction

non-disjunction : when the homologous chromosomes stick together instead of separating during meiosis

nondisjunction results in two types of gametes : one that has an extra chromosome (24), or one that lacks a chromosome (22)

genetic disorders that can come from disjunction : XXX female, XXY Klinefelter’s male and XO Turner’s Female

XXX female : infertile, taller, delays in puberty, 47 chromosomes

XXY Klinefelters male : Infertile, 47 chromosomes, cant produce testosterone properly, female characteristics

XO Turners female : infertile, short, 45 chromosomes, only condition that can survive with 45 chromosomes

Autosomal non-disjunction can also cause Autosomal Monosomics, Trisomy with an #13, 15 or 18 (severe defects, live only 3 months) or trisomy with an extra #21 (intellectual disabilites, skeletal defects)

TRISOMY 21 = DOWN SYNDROME

down syndrome causes intellectual disabilities, abnormal facial traits, they have 3 copies of the chromosome 21 (trisomy)