Genetics Flashcards
Leukemia associated with DS
Acute lymphocytic leukemia (but acute myeloblastic leukemia if in first 3 years of life)
Natural Hx of DS
– Major cause for early mortality is congenital heart disease
– Muscle tone improves with age
– Rate of development slows with age
– Early onset of Alzheimer disease
______is the second most common pattern of human malformation.
Edwards syndrome
SSx of Edwards syndrome
– Mental retardation
– Low-set, malformed ears; microcephaly, micrognathia; prominent occiput
– Clenched hand—index over third; fifth over fourth
Cardiac abn associated with Edwards
– VSD, ASD, PDA, cyanotic lesions,
Ortho abn associated with Edwards
– Rocker-bottom feet, hammer toe
GI abn associated with Edwards
– Omphalocele
Natural Hx of Edwards
– Many spontaneous abortions
– Feeble from birth
– Most do not survive first year
defect of midface, eye, and forebrain development → single defect in first 3 weeks’ development of prechordal mesoderm. It involves older maternal age
Patau syndrome
Asscn with Patau
– Scalp defects in parietal-occipital area (cutis aplasia)
– Postaxial polydactyly
Deletion asstd with WAGR syndrome
11p13; Wilms + Aniridia + GU anomalies + MR
– Decreased IQ (average IQ 85−90)
– Behavioral/psychiatric problems
– Long limbs (decreased upper:lower segment ratio)
Klinefelter Syndrome (XXY)
– Congenital lymphedema, residual puffiness over dorsum of fingers and toes
– Broad chest, wide-spaced nipples
– Low posterior hairline; webbed posterior neck
– Cubitus valgus (elbow) and other joint problems
– Horseshoe kidney, and other renal defects
Turner Syndrome (XO)
MC cardiac abn asstd with Turner
° Bicuspid aortic valve (number 1 cardiac anomaly)
° Coarctation
Natural Hx of Turner
– Decreased height velocity with delayed bone age
– Estrogen treatment indicated
– May increase height by 3−4 cm with growth hormone (GH)
Fragile X syndrome
Fragile site on _________in affected males and some carrier females—
Molecular diagnosis—variable number of repeat ______(preferred diagnosis = DNA-based molecular analysis)
long arm of X
CGG
Features of Fragile X
– Mild to profound mental retardation; learning problems
– Large ears, dysmorphic facial features, large jaw, long face
– Large testes—mostly in puberty (macroorchidism)(fertile
Genetic abn in Beckwith-Wiedemann Syndrome
– IGF-2 disrupted at 11p15.5 (imprinted segment)
Findings of Beckwith-Wiedemann Syndrome
– Macrosomia
– Macroglossia—may need partial glossectomy
– Pancreatic beta cell hyperplasia—excess islets → hypoglycemia