3 - Chromosomal disorders Flashcards
physical features of Down synd
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
clinical features of Down synd
~half have congenital heart defect (mostly ASD)
GI - duodenal atresia, Hirschprung dz, celiac
Heme - AML > megakaryoblastic leukemia
hypothyroid
alzheimer’s dz
Robertsonian translocation - def
translocation btwn acrocentric chromosomes - long arms join together, no deficit from not having the short arms
acrocentric chromosomes
ones w/ 1 really short arm and 1 long arm
13,14,15,21,22
2 MC robertsonian translocations
13q14q
14q21q
trisomy 18 =
Edward’s synd
trisomy 18 - what causes it
assoc w/ adv maternal age
most due to de novo meiotic nondisjunction
physical features of trisomy 18
microcephaly, microphthalmia, low set / malformed ears, micrognathia, small mouth, triangular face, rocker bottom feet, overlapping fingers
clinical features of trisomy 18
growth def heart dz - valvular, VSD cryptorchidism, renal anomalies severe ID brain anomalies, hypertonia, seizures
outlook for trisomy 18
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
cause of trisomy 13
75% nondisjunction (assoc w/ adv maternal age)
20% Robertsonian translocation
outlook for trisomy 13
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
physical features of trisomy 13
holoprosencephaly, microcephaly, scalp defects, malformed / low set ears, microphthalmia, iris and retinal colobomas, cleft lip and palate, postaxial polydactyly
clinical features of trisomy 13
seizures, growth def, heart: VSD/ASD, apnea
Williams synd cause
microdeletion in 7q11.23 (includes ELN gene)
features of Williams synd
mild ID (IQ~80), overfriendliness, ADD, large vocabulary, elastinopathy > cardio (supravalvular aortic stenosis, aortic hypoplasia), renal artery stenosis > HTN, hyperCA, renal anomalies, nephrocalcinosis
Prader-Willi syndrome cause
deletion of 15q11-q13 (paternal) in 70%
maternal uniparental disomy in 25%
features of Prader-Willi synd
severe hypotonia, poor feeding, cryptorchidism, voracious appetite > obesity, short stature, small hands/feet, ID, OCD, almond shaped eyes
cause of Angelman synd
microdeletion at 15q11-13 (maternal) in 70%
11% mutations in UBE3A gene (imprinted gene)
2-5% paternal uniparental disomy
features of angelman synd
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
22q11 deletion disorders and which is more severe
DiGeorge - most severe
velocardiofacial syndrome
features of velocardiofacial syndrome
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
Digeorge syndrome features
tetralogy of fallot, truncus arteriosus, VSD hypoCA thymic hypoplasia mild ID hypertelorism, low set ears, bifid uvula
