QF-PCR Aneuploidy Testing Flashcards
the gain or loss of a chromosome
aneuploidy
define non-disjunction
failure of one or more pairs of homologous chromosomes or sister chromatids to separate normally during nuclear division, usually = abnormal distribution of chromosomes in the daughter nuclei
Turner Syndrome
Monosomy X; 45,X
- usually paternal non-disjunc
- short stature, webbed neck, low hairline, normal intelligence, loss of ovarian function, cardiac defects and kidney disease
frequency of Turner Syndrome
1 in 2500 newborn girls worldwide
Klinefelter syndrome
47, XXY
- paternal or maternal non-disj
- tall with long limbs
- small testes, penis, breast growth, decrease sexual interest, lower than ave intelligence
Trisomy X
47, XXX
- most common female sex chromosome aneuploidy
- maternal non-disj
- taller than average, developmental delays
XYY syndrome
Jacob’s syndrome; 47 XYY
- paternal non-disj or post-zygotic cleavage errors
- tall, enlarged head, anti-social, learning disabilities, usually fertile
- 1 in 1000 live male births
Patau syndrome
Trisomy 13; somatic; 47, XX or XY+13
- non disj of either parent
- small eyes, extr digits, cleft palate, hart and CNS defects
- 90% infants die within a year
diagnosis for Patau syndrome
quad test
- low free estriol
- low AFP
- low inhibin A
- low B-HCG
central walls of heart not formed
Patau
clenched fists
Patau
Edwards Syndrome
Trisomy 18; 47, XX or XY+18
- maternal non-disj usually
- small, long head, small mouth, underweight, feeding and breathing problems, heart and genitourinary issues
- severe cognitive impairment
- freq increases with maternal age
- 90% infants die within a year
overlapping fingers
Edwards
clubfeet
Edwards
Downs Syndrome
Trisomy 21; 47, XY or XX+21
- majority maternal non-disj
- craniofacial abnormalities, heart defect, childhood leukemia, early-onset Alzheimer’s, mild to moderate cognitive impairment
- freq increases with maternal age
