Chromosomal anomolies Flashcards
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)
