Common Chromosomal Disorders Flashcards
Inheritance of an extra copy of one chromosome results in a condition called _____.
trisomy
Most commonly, trisomies occur when one pair of chromosomes fails to separate properly during meiosis, a problem termed _____.
nondisjunction
The most common trisomy that results in a live birth is trisomy _____ (#).
21
The most common trisomies are _____ (#), _____ (#), and _____ (#), and contain relatively few gene alleles.
21, 18, 13
Trisomy of chromosomes containing more alleles is more likely to be embryo _____.
lethal
The presence of extra sex chromosomes, especially the _____ chromosome, is relatively common.
X
What type of congenital heart defect is most common in trisomy 21?
cardiac cushion defects
Name the trisomy:
- small, strawberry-shaped head with receding chin, small jaw, and elongated occiput
18
Name the trisomy:
- microcephaly, micrognathia, cleft lip
13
Name the trisomy:
- epicanthal folds with upslanting palpebral fissures
- short neck with limited motion and extra skin folds
- cardiac cushion defects
21
Name the trisomy:
- atrial-septal defects, ventricular-septal defects, coarctation of the aorta
- omphalocele
- esophageal atresia
18
Name the trisomy:
- dextrocardia, atrial-septal defects, ventricular-septal defects, PDA
- polydactyly, syndactyly
- umbilical and inguinal hernias
13
Name the trisomy:
- holoproencephaly (fusion of brain hemispheres)
- low-set ears
- deafness, vision problems
- seizures
- apnea
13
Name the trisomy:
- Brushfield spots (speckling) on iris
- shorter stature than siblings
- hypothyroidism
- increased risk for leukemia
21
_____ with trisomy 21 are sterile.
Males
Females with trisomy 21 have a _____% chance of producing a zygote with trisomy 21.
50
Of those that are not stillborn, over _____% of trisomy 18 births die within the first year.
90
Of those that are not stillborn, over _____% o trisomy 13 births die within the first year.
90
List the 4 syndromes of extra X chromosomes:
trisomy X
tetrasomy X
pentasomy X
Klinefeltier syndrom
While _____ X is more common with normal phenotype (but usually are taller than average with slight delay in language development and a higher incidence of shyness and lack of self-confidence), _____ X and ______ X are much rarer are are consistently associated with phenotypic abnormalities.
- trisomy
- tetrasomy
- pentasomy
Females with _____ X are usually tall and have a greater reduction in IQ (35-70), smaller heads, and minor changes in facial features with increased incidence in skeletal abnormalities and unstable behavior.
tetrasomy