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17 Cards in this Set

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TRISOMY 21 (DOWN'S SYNDROME)

list incidence in newborns, physical characteristics, and etilogy
incidence is 1/600
hypotonia, poor moro reflex, anomalous ear auricles, simian crease, dysplasia of midphalanx of 5th finger, hyperflexibility of joints
95%--nondisjunctional trisomy 21; 1% trisomy 21/normal mosaicism; 4% is translocation
TRISOMY 18 (EDWARD SYNDROME)
incidence is .3/1000
more females affected
excess amniotic fluid and decreased fetal activity and single umbilical artery are prenatal diagnostic features
personal characteristics are hypertonia, microcephaly, small jaw, clef lip/palate, 12th rib missing
etiology is nondisjunctional events
maternal age is a factor translocation rare
TRISOMY 13 (Patau syndrome)
incidence is .2/1000 live births
midfacial and forebrain development, congenital deafness, small eyes, head and jaw;polydactyly (extra digits), syndactyly (fused digits)
nondisjunctional event
maternal age is a factor
translocations are rare
microdeletions sydromes
smith-magenis
prader-willi
williams
velocardiofacial
velocardialfacial syndrome
microdeletion on chromosome 22q11
mostly de novo deletion about 94%
6% inherited deletion from a parent
hypocalcemia and immunodeficiency among common problems
cri-du-chat syndrome
partial deletion of short arm of chromosome 5
most are de novo deletion
intrauterine growth retardation, microcephaly, adn cat-like cry
47 XXY
phenotypically normal male
fertile
tall thin stature
poor fine motor coordination
extra y chromosome from parental nondisjunction event in meiosis II
maternal age not a factor
47 XXY (klinefelter syndrome)
1/500 males affected
males are infertile
low IQs
tall slim statures
gynecomastia
meiotic disjunctions in paternal or maternal chromosomes
45X (turner syndrome)
1/5000 live births
small stature
transient congenital lymphedema
MENTAL RETARDATION IS NOT A FEATURE
maternal age not a factor
paternal sex chromosome missing
some are fertile
pterygium colli (webbed neck)
partial triploidy
have large placentas
cystic hydatiform
simian creases and syndactyly are present
congenital heart defects
all die in early neonatal period
mosaicism usually survive
etiology of triploidy
most cases, extra set of chromosomes is paternal
maternal age not a factor
fertilization by 2 sperms or fertilizatio to a diploid ovum
>99% are lost in early pregnancy
accounts for 20% of chromosomally abnormal spontaneous miscarriages
classic hydatiform moles
23X sperm fertilizes an ovum that lacks a nucleus (so no chromosomes)
chromosomes then double
these moles are 46XX (are all of paternal origin)
just trophoblast formation, no viable fetus
recurrence risk of down's syndrome
likelood is 1% or teh mother's maternal age related risk (whichever is greater)
50 percent of all translocation cases are inherited from a carrier parent
for a balanced translocation, the risk that the fetus will be affected is 10-15 percent if mom is the carrier and less than 5% if dad is the carrier
survival rate of babies with trisomy 18
30% die within the first month
50% die by 2 months
10% survive to first year with severe mental retardation
chromosomal abnormality where maternal age is a factor
trisomy 21--down syndrome
trisomy 18--edward syndrome
trisomy 13--patau syndrome
XXY syndrome
chromosomal abnormality where paternal age is a factor
partial triploidy
XYY syndrome
XXY syndrome
turner's syndrome
prognosis of trisomy 13--patau syndrome
80% die in first month
only 5% survive the first 6 months