Chromosomal anomolies Flashcards
(19 cards)
What are the three trisomies compatible with life?
13, 18, 21
What is the cause of Down Syndrome?
Trisomy 21
What is the incidence of Down Syndrome?
1/600 live births
What are the symptoms of Down Syndrome?
- hypotonia, open mouth and protruding tongue
- CNS: moderate intellectual disability
- Head: brachycephaly, flat occiput
- Eyes: upward slanting palpebral fissures, epicanthal folds, brushfield spots (white spots in eyes)
- Ears: small pinnae and lobule, overfolding of upper helix
- Hands: Brachydactyly, brachymesophalangia, single flexion crease/transvere palmar crease
- Wide gap between first and second toes
- Heart anomalies
- GI: atresias (failure of lumen to form)
- Genitourinary: small penis, infertility in males
- Skin: cutis marmorata (lacy ringlets)
What congenital cardiac defects are commonly associated with Down Syndrome?
- Atrial septal defect = hole connecting atria
- Ventricular septal defect = hole connecting ventricles
- AV canal or endocardial cushion defect = communication between all four chambers
What is the expected survival age with Down syndrome?
40-50
What is the incidence of trisomy 13?
1/5000 live births
What are the symptoms of trisomy 13?
- holoprosencephaly/incomplete forebrain development
- severe mental deficiency
- seizures, apnea, sensorineural deafness
- Craniofacial: scalp defects, microcephaly, sloping forehead, wide sutures and large fontanelles, redundant neck skin, cleft lip/palate
- Eyes: microphtalmia, colobomata of iris, retinal dysplasia
- Hands/feet: transverse palmar cerase, narrow and hyperconvex nails, camptodactyly, post-axial polydactyly, prominent heels
- Heart: ASD, VSD, PDA, dextroposition
- Genitalia: cryptochidism, abnormal scrotum, bicornuate uterus
- Skin: hemangiomas
What is the expected survival with trisomy 13?
82% mortality by 12 months
What is the incidence of trisomy 18?
1/3000 live births
What are the symptoms of trisomy 18?
- Polyhydramnios, small placenta, single umbilical artery
- Small for gestational age, pre or post-mature
- Underdevelopment of skeletal muscle and subcutaneous tissue
- Craniofacial: prominent occiput, small jaw, narrow bifrontal diameter, palpebral fissures, low-set ears
- CNS: severe intellectual disability, hypertonic
- Hands and feet: clenched hand and overlapping fingers, hypoplastic nails, no flexion crease on 5th finger, short hallus, dorsiflexed, rocker bottom feet
- Thorax: short sternum and thin ribs
- Cardiac: VSD, ASD, patent ductus areteriousis
- Pelvis: small pelvis, limited hup abduction
- Genitalia: cryptorchidism
- Skin: redundancy, excess hair, cutis marmorata
What is the expected survival with trisomy 18?
90% mortality by 18 months
What is the incidence of trisomy 16?
- Never in live birth
- Most common trisomy causing spontaneous miscarriage
What is the cause of Turner syndrome?
Monosomy X
What is the incidence of Turner syndrome?
1/2500 females
What are the symptoms of Turner syndrome?
- Short stature
- Poor coordination and delayed motor skills
- Poor visual-spatial organization
- Poor social cognition
- Failure to develop secondary sex characteristics at puberty, sterile, ovarian dysgenesis (“streak ovaries”)
- Wide carrying angle
- Craniofacial: epicanthal folds, low-set ears, low hairline, redundant neck skin, webbed neck
- Hands and feet: short 4th knuckles, edema, narrow and hyperconvex nails
- Broad chest and widely spaced nipples
- Heart: bicuspid aortic valve (rather than tricuspid), coarctation (constriction) of aorta
- Hearing impairment
- Horseshoe kidney
What treatments are used for Turner syndrome?
- Growth hormone injections
- Hormone replacement therapy when puberty should occur
What is the cause of Williams syndrome?
Microdeletion 7q11.23
What are the symptoms of Williams syndrome?
- Distinctive facies (big mouth, full lips, prominent cheeks, iris with white streaks)
- loquacious personality
- intellectual disability
- hypercalcemia
- supravalvular aortic stenosis (constriction)
