Genetic Diorders/Inborn Metabolism Flashcards
Uniparental disomy
instead of inheriting one gene/chromo from each parent, both parts are from one parent
Genomic imprinting
gene defect expressed solely based on sex of parent passing on defective gene
ie, mother passes on 11q abnormality of chromo 15- Angelman, but w/ father, Prader-will. (Paternal prader willi)
Abnormal Morpho
Malformation- intrinsincally abnormal process forms abnormal tissue (bladder extrophy b/c infraumb mesenchyme doesn’t migrate)
Deformation- mech forces on normal tissue => abnormal
Disruption- normal tissue becomes abnormal after destructive forces (ischemia, hypoxia)
Syndrome- unrelated abnormal features in a familiar patter
Maternal serum markers
AFP- elevated with NTDs, twins, underestimated GA, ab wall defect, fetal emise, fetal edema condictions. Low = overest GA, trisomy 21 and 18, IUGR
Triple marker = AFT, estriol, BHCG- all low= 18, low low high = downs
Genetic fetus eval
CVS- at 10-13weeks, can do karyotyping, DNA extract, enzyme analyses
Amnio- cells lsoughed off 16-18 weeks
PUBS- sample of fetal blood, look fo rmee abnormal, genetic disorders, infec, acidosis, or transfuse fetus
Marfans
Auto dom, Ocular, CV, skeletal, Chromos 15 for fibrillin
Clin- tall, elongated extremities/fingers, scoliosis/kyphosis, decreased upper to lower seg ratio (shorter torso)
Dx- clinical findings, but distinguish from homocystinuria w/ screening test. Upward lens sublux, retinal detach, aortic root dilatation, MV prolapse, mitral regurge
Compx- endocarditis, retinal detachment, sudden death from aortic dissection- HTN/chest trauma increase dissection risk, reduce w/ B block and avoid contact sports
Endocarditis prophylaxis + regular optho evals
Prader-Willi
Genomic imprinting, absence of a region on the paternally derived chromosome 15
Fx- almond eyes, fishlike mouth, FTT, feeding struggz in year 1, obesity from hyperphagia later, short stature/small hands/feet
Neuro- hypotonia in new born, mental retardation, learning disab, bheavioral problems, hypogonadism
Dx- FISH chormo deletion
Compx- poor sucking/feeding probs, then in childhood, OSA, in adulthood, cvd and t2dm + pscyh illness
Angelman
Happy puppet (puppety gait and smiling kid) Imprtining- deletion on chromo 15 MATERNAL Clin- jerky arm mvt, ataxia, inapropro laughing, mental retardation + speech delay. craniofac = small wide head, large mouth/wide spaced teeth, tongue protrusion, prognathia. blond hair/pale blue dep set eyes Dx- FISH
Noonan
Sporadic or maybe auto dom, chromo 12. mainly males, but maybe females too!
Clin- short stature, shied chest, web neck, low hairline, hypertelorism (wide set eyes), epicanthal skin folds, downslant palpebral fissures, low ears.
RIGHT sided heart lesions, PUlm VALVE stenosis (turners has left)
Dx= clin features
DiGeorge
22q11 deletion- CATCH-22
Cardiac, abnormal facies, thymic hypoplasia, cleft palate, hypocalcemia, gene defect 22. Sporadic and autodom
Digeorge = short palpebral fissures, small chin, ear anomalies, aortic arch anomalies, VSD, tet of fallot. thymus/parathyroid issue => immunodef + severe hypocalc
Dx w/ FISH
Compx- infections from cell med immunodef and seizures (hypocal)
Velocardiofacial
cleft palate, wide prom nose + squared nasal root, short chin, fish mouth, cardiac = VSD and R sided aortic arch, neonate hypotonia, learning disab, perseverative behaviors
Dx= fish probes
Ehlers Danlos
Defective type V collagen => hyperextensible joints + frag vessels + loose skin, auto dom
Clin = hyperextensible => joint disloc + scoiosis, velvety loose skin, paper thin scars, large wounds, mv prolapse, aortc root dil, frag blood vessels. GI = constipation, rectal prolapse, hernias
Dx clinically, compx = aortic dissection _ GI bleeds form blood fragility
Osteogenesis Imperfecta
Abnormal type I collagen. Four types, here is type I
-blue sclerae, fragile bones => frequent fractures, genu valgum (knock knees), scoliosis/kyphosis, joint lax, osteoperosis/penia, yellow/gra/blue teeth, easy bruisng
Dx = clin fx + decreased type I collagen synth in fibroblasts
Compx = early conductive hearing loss, skeletal defomrities
VACTERL
Sporadic group of malform
Vertebral defects, anal atresia, Cards anomalies (VSD), TE (fistula0, Renal (and genital), limb defects (radial hypoplasia, syndactyly, polydactyly)
Dx on features
CHARGE association
Colobomas of retina, impaired vision Heart defects (tet of fallot) Atreasia (of nasal chonae) Retardation of growth/cognition Genital anomalies (hypoplasia) Ear anomalies (cup shaped ears, hearing loss) Dx on fx
Williams syndrome
Deletion on chromo 7, gene for elasti, auto dom
Cocktail party personality, elfin facies, short palpebral fissues, flat nasal bridge, round cheeks, mental retard, loquacious personality, supravalvular aortic stenosis, idiopathic hyperca, connective tissue abnormal (hoarse voice/hernias)
DX w/ FISH probes
Cornelia de Lange (Brachmann)
Single eyebrow, short stature, no skeletal abnormal, sporadic inheritance, maybe auto dom
Clin- SGA< FTT, synophrys, long curly eyelashes, microceph, thin down turned upper lip, micrognathia, HYPERtonia, mental retardation, small hands/feet, heart defects, autism, SELF-detructive, no facial expression
dx = clin fx
Russel Silver
Sporadic inheritance
Short stature/skel asymm/normal head circ
Clin fx- SGA, triangular face, prom forehead, downturned mouth, head looks large but isn’t
Skel findings = short stature, limb asymm, cafe au lait, excessive sweat
On clin fx
Pierre Robin
Micrognathia, cleft lip/palate, large protruding tongue
Dx on clin fx
Compx = recurrent OM< upper airway obstruction needing tracheostomy
Cri du Chat
Partial deletion of short arm chromo 5
Clin fx = slwo growth, microceph, mental retardation, hypertelorism, downslanting palpebral fissures, catlike cry
Dx on chromo deletion/presence of clin fx
Down Syndrome
Trisomy 21, most common trisomy
AMA, increased nondisjunction in ovum
1:600 live births
Clin fx = brachyceph, epicantahl skin folds, upslant fissures, speckled irises, protruding tongue, hypotonia, mr, single palmar crease, flip flop spot, clinodactyly, duod atresia, hirschprung, omphalo, pyloric sten, endocardial cushion
Compx- atlanto axial cervical spine instab, leukemia, celiac disease (IgA/anti-endomysium antibody), early alzhemier’s, OSA< conductive hearing oss, hypothyroidism, cataracts, glaucoma, refrac errors :(
Trisomy 18
Second most common, 3x more common in females
Clin fx- MR, hypertonia, scissoring lower extremities, delicate small face, clenched hands, overlapping digits, ROCKER bottom feet, dorsiflexed big toes
Dx- chromo analysis
prog- 95% die in first year :(
Trisomy 13
MIdline defects- holopropsencephaly, microceph, seizure, severe MR
Microphthalmia, retinal dysplasia, colobomas, Single ey, cleft lip palate
Dx- chromo analysis, prog - death in first months of life
Turners
Only one X- 1;2000
Clin- short stature, web neck, shield chest (scoliosis/kyphosis), swelling dorsum hands/feet, ovarian dysgenesis- pubertal delay, L sided heart lesions, coarctation of the aorta, bicuspid aortic valve, hypoplastic L heart, hypothyroidism
Dx- clin features, chromo analysis
Fragile X
X-linked disorder on X chromo, CGG repeats, anticipation
More severe in males, MR in females (1;1.25K males, , i in 2.5K females)
MOST COMMON FORM OF INHERITED MR
Clin- severe to mild mr, large ears, macrocephaly, thickened nasal bridge, blue irises, large testes in puberty
Behavioral 0- emotional instability, autistic, ADHD
Dx- chromo