Flashcards in Abnormalities in Chromosome Number (Self and Lecture) Deck (17):
What is trisomy 21
What causes trisomy 21
List 3 Things
Meiotic Nondisjunction 95% of the time in maternal meiosis 1. 2-4 % of the time it will be a mosaicism, and robertsonian translocation
What is the prevalence of the disease ?
1 in 800 live births and only 20% make it to a live birth
What is trisomy 18
Edwards syndrome, rocker bottom feet and clenched hands, prenatal growth deficiency and congenital heart defects.
What causes trisomy 18 ?
(47 XX +18) ( or 47 XY, +18) caused by maternal nondisjunction.
What is the incidence of trisomy 18 ?
1 in 6000 live births less than 5% make it to survival
What is Patau Syndrome ?
Trisomy 13- results in abnormal development of the mid face, eye, and forebrain. Polydactaly, Microphyhalmia, congenital heart defects.
What causes Patau Syndrome ?
80% maternal nondisjunction
<20% Robertsonian Translocation involving chromosome 13.
-Rare cases of mosasicism
What has more serious phenotypes, Sex Chromosome abnormalities or somatic abnormalities ?
Sex chromosome abnormalities are much less severe. We all only have one active X because of X inactivation. ***YOU have to have atleast 1 X to survive
What is turners syndrome ?
Primary Hypogonadism characterized by short stature and ovarian dysgenesis.
What causes Turner Syndrome ?
45X and variants. caused by paternal nondisjunction and is not associated with advanced age.
What is Klinefelter Syndrome ?
15% can have mosaicism (46 XY / 47, XXY)
What causes Klinefelter syndrome ?
50 % paternal nondisjunction (XY)
50% Maternal nondisjunction
1/1000 male live births, 1/2 are spontaneously aborted.
What will a kid with klienfelter syndrome look like ?
Mostly in males,
Tall with long extremities
What is triple X syndrome ?
1/1000 female live births
90% maternal nondisjunction with age effect
Normal phenotype with mild learning problems
What is 47 XYY syndrome ?
Paternal meiosis 2 nondisjunction, no age effect
Normal phenotype, tall, educational and behavioral problems