3 - Chromosomal disorders

Question 1

physical features of Down synd

Answer 1

general hypotonia
microcephaly, brachycephaly
small round ears, uplanting palpebral fissures, epicanthal folds, midface hypoplasia, tongue protrusion
ID (avg IQ 40-60)
broad short neck, redundant skin
brachydactyly, single transverse palmar crease, 5th finger clinodactyly
sandal gap deformity

Question 2

clinical features of Down synd

Answer 2

~half have congenital heart defect (mostly ASD)
GI - duodenal atresia, Hirschprung dz, celiac
Heme - AML > megakaryoblastic leukemia
hypothyroid
alzheimer’s dz

Question 3

Robertsonian translocation - def

Answer 3

translocation btwn acrocentric chromosomes - long arms join together, no deficit from not having the short arms

Question 4

acrocentric chromosomes

Answer 4

ones w/ 1 really short arm and 1 long arm

13,14,15,21,22

Question 5

2 MC robertsonian translocations

Answer 5

13q14q

14q21q

Question 6

trisomy 18 =

Answer 6

Edward’s synd

Question 7

trisomy 18 - what causes it

Answer 7

assoc w/ adv maternal age

most due to de novo meiotic nondisjunction

Question 8

physical features of trisomy 18

Answer 8

microcephaly, microphthalmia, low set / malformed ears, micrognathia, small mouth, triangular face, rocker bottom feet, overlapping fingers

Question 9

clinical features of trisomy 18

Answer 9

growth def
heart dz - valvular, VSD
cryptorchidism, renal anomalies
severe ID
brain anomalies, hypertonia, seizures

Question 10

outlook for trisomy 18

Answer 10

50% die by 2 mo, 1y. usually die from heart problems or apnea
will never talk, probably never walk (if they do it will be with great difficulty), need to be fed

Question 11

cause of trisomy 13

Answer 11

75% nondisjunction (assoc w/ adv maternal age)

20% Robertsonian translocation

Question 12

outlook for trisomy 13

Answer 12

mean life expectancy 4 mo
45% die in 1 mo, 70% by 6 mo, 86% by 1 y
can never really do anything but lie there and have seizures

Question 13

physical features of trisomy 13

Answer 13

holoprosencephaly, microcephaly, scalp defects, malformed / low set ears, microphthalmia, iris and retinal colobomas, cleft lip and palate, postaxial polydactyly

Question 14

clinical features of trisomy 13

Answer 14

seizures, growth def, heart: VSD/ASD, apnea

Question 15

Williams synd cause

Answer 15

microdeletion in 7q11.23 (includes ELN gene)

Question 16

features of Williams synd

Answer 16

mild ID (IQ~80), overfriendliness, ADD, large vocabulary, elastinopathy > cardio (supravalvular aortic stenosis, aortic hypoplasia), renal artery stenosis > HTN, hyperCA, renal anomalies, nephrocalcinosis

Question 17

Prader-Willi syndrome cause

Answer 17

deletion of 15q11-q13 (paternal) in 70%

maternal uniparental disomy in 25%

Question 18

features of Prader-Willi synd

Answer 18

severe hypotonia, poor feeding, cryptorchidism, voracious appetite > obesity, short stature, small hands/feet, ID, OCD, almond shaped eyes

Question 19

cause of Angelman synd

Answer 19

microdeletion at 15q11-13 (maternal) in 70%
11% mutations in UBE3A gene (imprinted gene)
2-5% paternal uniparental disomy

Question 20

features of angelman synd

Answer 20

microcephaly w/ nl head circumference at birth, brachycephaly, midface retrusion, prognathism, wide spaced teeth, drooling, macrostomia
severe ID (IQ<40), seizures, abnl EEGs, no speech, unprovoked bursts of laughter, ataxia, wide based gait w/ upheld arms, poor coordination, tremors

Question 21

22q11 deletion disorders and which is more severe

Answer 21

DiGeorge - most severe

velocardiofacial syndrome

Question 22

features of velocardiofacial syndrome

Answer 22

heart dz - tetralogy of fallot, interrupted aortic arch B, truncus arteriosus, VSD/ASD
cleft palate, velopharyngeal incompetence, bifid uvual > high pitched / nasal voice
feeding difficulties
long face / fingers, small/cupped ears, prominent nose
renal abnlties
mild ID
hypoCA
psych illness >40% w/ schizophrenia or bipolar disorder

Question 23

Digeorge syndrome features

Answer 23

tetralogy of fallot, truncus arteriosus, VSD
hypoCA
thymic hypoplasia
mild ID
hypertelorism, low set ears, bifid uvula