Genetics Flashcards
What is malformation?
something went wrong from the beginning.. morphological defect during development process
What is disruption?
Disruption of normal developmental process.. like shortened limbs
What is deformation?
Results from mechanical issue, eg club feet
Most common cardiac anomaly with 22q11?
Conotruncal defects (VSD is MOST common of these)
Most common genetic defect in Noonan syndrome?
PTPN11 (50%)
Autosomal dominant
Most common CHD in Noonan syndrome?
Pulmonary stenosis, hypertrophic cardomyopathy
What does a karyotype test for?
Numerical abnormalities.. Also known as chromosomal analysis. Looks at larger abnormalities ie trisomies, translocations
What does a microarray look at?
Microdeletions and duplications
Which sources will accurately give us neonatal genetic testing? (blood etc)
Baby’s blood, amnio (baby’s skin cells) and cord blood.
CVS can have mixed cells.
Most common major malformation?
Neural tube defects
Which chromosomes can be involved in Robertsonian translocation?
Chromosome 13, 14, 15, 21 and 22
Most common single gene disorder in Caucasians?
Cystic fibrosis (autosomal recessive)
Clinical features of Trisomy 13
Patau syndrome Extra chromosome maternal origin Midline abnormalities Cutis aplasia Hyperconvex fingernails Cleft lip, palate, small eyes Holoprosencephaly
Clinical features of Trisomy 18
Edward syndrome
Clenched hands, rocker bottom feet
Small mouth, micrognathia
IUGR, short sternum
Clinical features of Trisomy 21
Endocardial cushion defect Transverse palmar crease Upslanting palpebral fissures Flat nasal bridge Brushfield spots (speckled iris) Epicanthal folds Large tongue Short neck Hypotonia TMD
Postnatal eval for trisomy 21
Echo Red reflex (may have cataract) Swallow study for feeding issues CBC for TMD TFTs Car seat test Hearing
Features of cri du chat
5p deletion (paternal origin) Hypertelorism, downward slanting palpebral fissures Cat like cry, mental deficiency, microcephaly FTT
Features of Angelman syndrome and mode of inheritance
Microdeletion of maternal origin (maternal imprinting OR paternal uniparental disomy) of 15q11-13
Inappropriate bursts of laughter, blond hair, light colored eyes
Ataxia, jerky movements
Puppet like gait
High amplitude spikes on EEG
Most common chromosomal deletion in humans?
22q11.2 syndrome/DiGeorge syndrome/velocardiofacial syndrome
Features of DiGeorge syndrome
Defect in 4th brachial arch Aortic arch abnormalities Hypoplastic to aplastic thymus Cleft lip/palate Hypocalcemia Deficient cellular immunity, developmental delay Poor feeding Butterfly vertebrae
Features of Prader-Willi and mode of inheritance
Microdeletion of 15q11-13, paternal origin (paternal imprinting OR maternal uniparental disomy)
Small hands, feet
Hypotonia
Undescended testes
FTT initially, then obesity because of increased appetite
Breech delivery
Almond shaped palpebral fissures, thin upper lip
Management of Prader Willi
Avoid G-tube for feeding issues
HCG may treat cryptorchidism
Growth hormone in older kids
Features of Williams syndrome
Deletion of 7q11.23 Supravalvular subaortic stenosis > PPS Hypoplastic nails Prominent lips Hoarse voice Stellate iris pattern
Features of Beckwith-Wiedemann
Autosomal dominant Polyhydramnios Macroglossia, linear earlobe fissures Macrosomia, organ hyperplasia Intraabdominal malignancies, hypoglycemia Needs tumor surveillance screening
Features of Holt Oram
Autosomal dominant
ASD (most common cardiac defect)
Upper limb defects
Absent or abnormal thumbs
Features of Marfan syndrome
Abnormal fibrillin gene
Dilated aorta
Arachnodactly, hyperextensibility, scoliosis
Upward lens sublaxation
Features of Noonan syndrome
Dysplastic pulmonary valve Pectus excavatum Webbed neck Cryptorchidism Abnormalities in coag pathway
DDx: Turner, Fetal alcohol syndrome, fetal hydantoin
Fanconi anemia
Autosomal recessive, increased chromosomal breaks in lymphocytes and amniotic fluid cells
- Hyperpigmentation
- Radial and thumb hypoplasia, short stature
- Pancytopenia
- Increased risk of AML
Most common inherited cause of mental deficiency?
Fragile X
Mobius sequence
Majority sporadic
Expressionless face
Micrognathia
Talipes equinovarus
Poland sequence
Proximal subclavian artery disruption
Hypoplasia or absence of unilateral pectoralis major
Which is not a part of mature messenger RNA?
Introns
They are part of the initial primary mRNA, but are spliced out when mature RNA is made
What are exons?
They are the DNA sequence that is transcribed, retained and is the final product
Role of poly-A tail
Aka polyadenylation sequence
Made of 100-200 adenine nucleotides
Role is to stabilize the mRNA
Attaches to the 3 end of primary and mature mRNA
What is the North, West and Southern blot analyses?
Northern blot: Digested RNA with DNA probe
Southern blot: Digested DNA with DNA probe
Western blot: Proteins separated and antibody probe used to identify protein of interest
Most common disorder of skeletal development in neonates?
Osteogenesis imperfecta
Robertsonian translocation in Down’s is most commonly with which chromosomes?
13, 14 and 15
Most common inherited cause of intellectual disability?
Fragile X
What is a promoter?
It is on the 5’ end region
RNA polymerase and transcription factors bind to initiate transcription
