Genetics Flashcards
It is a genetic syndrome characterized by midline defect- microphthalmia, cleft lip and palate, associate with VSD and dextrocardia
Patau syndrome- trisomy 13
Routine screen done on 1st TM that combine ultrasound of nuchal translucency and blood test- PAPP-A and B-HCG
Combine screening test
- done at 11-13 wks
- Detect aneuploidies with false positive rate 5%
newborn presenting with macrosomia, macroglossia, abdominal wall defect, hemi hyperplasia
Beckwith-Wiedemann syndrome
Perioperative challenge for children with beckwith-weidemann
Intubation/Airway due to macroglossia
Most common cause of trisomy 21
Non-disjunction (3 copies of chromosome 21)- 94%
others:
translocation- involve chromosome 14 and 21
Physical Features of T21
brachycephaly
flattened occiput
depressed nasal bridge
upslanting palpebral conjunctivae
epicanthal fold large protruding tongue
tranverse palmar crease
sandal gap
hypotonia
Congenital heart anomaly T21
endocardial cushion defect
AV canal, VSD, ASD
-Echo prior to d/c
Congenital GI defect T21
5-10% obstruction
Duodenal atresia
annular pancreas
Hirschsprung
anal atresia
Hematologic abN T21
- 50% polycythemia
- Leukmoid reaction or transient myeloproliferative d/o
- Inc risk 10-18x risk for Acute nonlymphblast leukemia (less 1 y/o), ALL
Common endocrine abN T21
hypothyroid (autoimmune thyroiditis)
DM
obesity
Medical issues of older T21
- Intellectual disability
- Seizure/ infantile spasm
- Dementia like syndrome
- Inc susceptibility to infection
- Strabismus/cataract
- Obstructive apnea
- Hearing loss
Outcome of T18
95% spontaneous abortion
Reocurrence rate 1%
Features T18
- dolichocephaly with prominent occiput
- micrognathia
- short palpebral fissures
- low set ears
- rocker bottom feet
- Over lapping 2nd & 5th digit over 3rd & 4th
gold standard to diagnose chromosomal abN during pregnancy
Amniocentesis
Reoccurence risk of T21
- Nondisjunction 1% above mom-age specific risk
- Unbalance translocation de novo- 1%
- Balanced translocation parent: 10-15% mom, 2-5% dad
No need to test parents if nondisjunction/mosaic
What is the syndrome which presents as:
A neonate presents with:
- short-limbed dwarfism
- fine, sparse hair that is lighter than that of other family members (hypotrichosis)
- immune deficiency.
Cartilage-hair hypoplasia
- mutation of the RMRP gene on chromosome 9p13
- autosomal-recessive
- most common in Old Order Amish and Finnish populations
Infant develops progressive abdominal distention. She does not have a spontaneous bowel movement. A contrast enema shows a narrow-caliber rectum and transition point in the sigmoid colon. A rectal suction biopsy finds no ganglion cells.
What does the baby have?
Hirsprung Disease
- congenital absence of enteric ganglia along a variable length of intestine,
- Incidence in 5,000 births.
- About 70% of HD cases occur in isolation
- Coexisting Down syndrome is present in 2% to 10%
Infant with
- rhabdomyoma
- hypopigmented ashleaf macules
- intracranial tumor
- seizure
- mental deficiency
- One parent has the same condition
Tuberous sclerosis
- autosomal dominant (chromosome 9 and 16)
Newborn presenting with
- pulmonic stenosis (60% incidence)
- hypertrophic cardiomyopathy
- short webbed neck, lymphedema
- hypertelorism, downward eye slanting, low-set ears
- pectus excavatum
- cognitive deficits (35% incidence)
- bleeding diathesis
Noonan syndrome
- autosomal dominant,
- a mutation in the PTPN11 gene
Newborn presenting with:
- omphalocele
- macroglossia
- macrosomia
- hemihyperplasia
- neonatal hypoglycemia
Beckwith-Wiedemann syndrome
Also presents with:
- visceromegaly
- embryonal tumors (eg, Wilms tumor),
- cytomegaly of the fetal adrenal cortex (pathognomonic if present)
genetic defect (most common to least)
- Gene imprinting
- Methylation defects
- paternal uniparental isodisomy
- craniosynostosis
- syndactyl of hands and feet (usually involves 3 digits)
Apert syndrome
- mild to severe intellectual disability
It is the most common of the syndromic craniosynostoses
- no hand/feet abnormalities
- no intellectual disability
- Hydrocephalus
Crouzon syndrome