Abnormalities in Chromosome Number (Self and Lecture) Flashcards Preview

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Flashcards in Abnormalities in Chromosome Number (Self and Lecture) Deck (17):
1

What is trisomy 21

Down Syndrome

2

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

3

What is the prevalence of the disease ?

1 in 800 live births and only 20% make it to a live birth

4

What is trisomy 18

Edwards syndrome, rocker bottom feet and clenched hands, prenatal growth deficiency and congenital heart defects.

5

What causes trisomy 18 ?

(47 XX +18) ( or 47 XY, +18) caused by maternal nondisjunction.

6

What is the incidence of trisomy 18 ?

1 in 6000 live births less than 5% make it to survival

7

What is Patau Syndrome ?

Trisomy 13- results in abnormal development of the mid face, eye, and forebrain. Polydactaly, Microphyhalmia, congenital heart defects.

8

What causes Patau Syndrome ?

80% maternal nondisjunction
<20% Robertsonian Translocation involving chromosome 13.
-Rare cases of mosasicism

9

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

10

What is turners syndrome ?

Primary Hypogonadism characterized by short stature and ovarian dysgenesis.

11

What causes Turner Syndrome ?

45X and variants. caused by paternal nondisjunction and is not associated with advanced age.

12

What is Klinefelter Syndrome ?

47XXY (85%)
15% can have mosaicism (46 XY / 47, XXY)

13

What causes Klinefelter syndrome ?

50 % paternal nondisjunction (XY)
50% Maternal nondisjunction
1/1000 male live births, 1/2 are spontaneously aborted.

14

What will a kid with klienfelter syndrome look like ?

Mostly in males,
Primary hypogonadism
Tall with long extremities
Gynecomastia
Reduced IQ

15

What is triple X syndrome ?

47XXX
1/1000 female live births
90% maternal nondisjunction with age effect
Normal phenotype with mild learning problems

16

What is 47 XYY syndrome ?

Paternal meiosis 2 nondisjunction, no age effect
Normal phenotype, tall, educational and behavioral problems

17

Is the incidence of down syndrome higher in young or old mothers?

Young