Genetics Flashcards
Patau syndrome
Trisomy 13
Most common recognizable cause of MR
Down syndrome
Patau syndrome findings
holoprosencephaly, polydactyly, cutis aplasia
Patau syndrome prognosis
< 20% beyond 1st year
Edward syndrome
Trisomy 18
Edward syndrome prognosis
< 10% survival beyond 1st year
Edward syndrome findings
Malformed ears, overlapping fingers, rocker-bottom feet, microcephaly w/ prominent occiput,
Turner syndrome findings
Short stature, short webbed neck, cubitus valgus, coarctation of the aorta, broad chest, widely apaces nipples, horseshoe kidney, ovarian dysgenesis
Turner syndrome genetics
45X (50%), structural abnormality of X (25%), mosaicism (25%)
Klinefelter syndrome findings
Tall, long limbs, female shape, scant facial/pubic hair, hypogonadism, small penis
Most common sex chromosome anomaly
Klinefelter syndrome
Klinefelter syndrome treatment
Testosterone replacement
Fragile X syndrome findings
Autism, MR, large ears, long narrow face, hyperextensible fingers, mitral valve prolapse, macro-orchidism
2nd most common cause of MR
Fragile X
Fragile X female carriers
1/3 with learning disability or mild MR
Prader-Willi syndrome findings
Neonatal hypotonia, almond shaped eyes, polyphagia, skin-picking behavior, MR
Prader-Willi syndrome genetics
Deletion at 15q11 (70%), uniparental disomy with loss of paternal allele (25%)
Angelman syndrome
Broad mouth, ataxia (puppet like gait), inappropriate laughter, absent speech
Angelman syndrome genetics
Deletions at 15q11 (70%), uniparental disomy with loss of maternal gene (7%)
Beckwith-Wiedemann syndrome
LGA, infantile hypoglycemia, macroglossia, earlobe creases, asymmetric limb length
Beckwith-Wiedemann syndrome complications
Increased risk for abdominal tumors (Wilms, heptoblastoma)
Beckwith-Wiedemann syndrome genetics
Methylation defects at 11p15
Williams syndrome complications
Supravalvular aortic stenosis, hypercalcemia, renal disease
Williams syndrome findings
Variable MR (IQ 50-90), cocktail party personality, elfin-like face, stellate irides, long philtrum, increased musical ability
Cri Du Chat syndrome findings
SGA, MR, high pitches cry, hypertelorism, epicanthal folds, profound speech impairment
Williams syndrome genetics
Sporadic - maternal UPD of ch 7 (10%), hypomethylation of 11p15
Cri Du Chat syndrome genetics
Sporadic 5p deletion
DiGeorge syndrome findings
Cardiac defects (esp. TOF), abnormal facies, thymic hypoplasia, cleft palate, hypocalcemia
DiGeorge syndrome genetics
Sporadic 22q11 deletion
Smith-Magenis syndrome genetics
17p11 deletion
Malformation
Morphological defect resulting from an intrinsically abnormal developmental process (eg cleft lip, CHD)
Deformation
Abnormal form of a body part caused by mechanical forces (eg clubfoot)
Disruption
Destruction of a previously normally formed body part. Causes include amniotic bands and vascular disruption (eg gastroschisis)
Dysplasia
Abnormal organization of cells in a tissue (eg ectodermal dysplasia)
Sequence
Cascade effect resulting from a single embryonic event (eg Pierre-Robin, DiGeorge syndrome)
Achondroplasia genetics
AD
Fibroblast growth factor receptor 3
Achondroplasia complications
Neonatal hypotonia, apnea 2/2 tight foramen magnum, spinal cord compression
Marfan genetics
AD
Fibrillin
Marfan complications
Ectopia lentis, MVP, aortic root dilatation, joint instability, PTX
Ehlers-Danlos genetics
AD
Type III or I’VE collagen
Osteogenesis Imperfecta genetics
AD
Type I collagen
Osteogenesis Imperfecta findings
Dentinogenesis Imperfecta, blue sclera, hearing loss
Anhydrotic ectodermal dysplasia
XLR
Hypotrichosis, hypotonia, anhydrosis, mild MR
Holt-Oram syndrome genetics
AD
TBX5 gene
Holt-Oram syndrome findings
CHD (esp. ASD), absent thumb, radial hypoplasia
Most common lethal skeletal dysplasia
Thanatophoric dysplasia
Treacher-Collins syndrome genetics
AD
TCOF1 (treacle)
Treacher-Collins syndrome findings
Mandibular hypoplasia, ear anomalies, eyelid colobomata, cleft palate
Goldenhar syndrome cause
Stapediel artery disruption
Goldenhar syndrome findings
Hemifacial microsomia, macrostomia (larger mouth on affected side), colobomata
Russell-Silver syndrome findings
Growth retardation, macrocepahly, blue sclera, triangular face, hypoglycemia