Chromosomal anomolies

Question 1

What are the three trisomies compatible with life?

Answer 1

13, 18, 21

Question 2

What is the cause of Down Syndrome?

Answer 2

Trisomy 21

Question 3

What is the incidence of Down Syndrome?

Answer 3

1/600 live births

Question 4

What are the symptoms of Down Syndrome?

Answer 4

• 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)

Question 5

What congenital cardiac defects are commonly associated with Down Syndrome?

Answer 5

• Atrial septal defect = hole connecting atria
• Ventricular septal defect = hole connecting ventricles
• AV canal or endocardial cushion defect = communication between all four chambers

Question 6

What is the expected survival age with Down syndrome?

Answer 6

40-50

Question 7

What is the incidence of trisomy 13?

Answer 7

1/5000 live births

Question 8

What are the symptoms of trisomy 13?

Answer 8

• 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

Question 9

What is the expected survival with trisomy 13?

Answer 9

82% mortality by 12 months

Question 10

What is the incidence of trisomy 18?

Answer 10

1/3000 live births

Question 11

What are the symptoms of trisomy 18?

Answer 11

• 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

Question 12

What is the expected survival with trisomy 18?

Answer 12

90% mortality by 18 months

Question 13

What is the incidence of trisomy 16?

Answer 13

• Never in live birth

- Most common trisomy causing spontaneous miscarriage

Question 14

What is the cause of Turner syndrome?

Answer 14

Monosomy X

Question 15

What is the incidence of Turner syndrome?

Answer 15

1/2500 females

Question 16

What are the symptoms of Turner syndrome?

Answer 16

• 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

Question 17

What treatments are used for Turner syndrome?

Answer 17

• Growth hormone injections

- Hormone replacement therapy when puberty should occur

Question 18

What is the cause of Williams syndrome?

Answer 18

Microdeletion 7q11.23

Question 19

What are the symptoms of Williams syndrome?

Answer 19

• Distinctive facies (big mouth, full lips, prominent cheeks, iris with white streaks)
• loquacious personality
• intellectual disability
• hypercalcemia
• supravalvular aortic stenosis (constriction)