-(1 in 800) 95% of time the female egg fails to separate durning meiosis; usually results of old eggs

-extra copy of chromosome 21

-short, flat facial profile, an upward slant to eyes, small ears, and a protruding tongue

most commonly involves an extra X or Y or absent of an X

-Typically error in division during meiosis

- often not recognized until puberty

one of the most commmon abnormalities; 1 in 500 men have and dont have any syntoms 

males have an extra X

hormone therapy at puberity to stimulate development of sex charactistics and sex drive

-usually fathers sperm contained neither X or Y

- generally tall and thin

- sometimes severeacne during adolesence

-antisocial or behavior problems

- increase learning disabilites and delay development of speach and language skills

(1 in 2500) Gentice disorder where infants cant break down an amino acid called phenyalanine

- its accumualtes in thier bodies and damages thier nervious system and can cause hyperactivity

-red blood cells are impacted and occurs most often in individuals of african desent

- 60000 people in the us affected

- name comes from the shape of the red blood cells longated and bent

-gets stuck in small blood vessels of joints and abdmen which reuslts in severe pain, tissue damage and death 

-spleen removes problem cells