Patau, Edwards, Noonan Flashcards
What is Patau’s syndrome and how common is it?
· Trisomy 13; 1 in 14,000 births
· 80% die in first month of life, 90% by 1 year of age
What investigations do you do for Pataus?
Antenatal screening
o Biochemical
▪ In first trimester, HCG and PAPP-A are lower than expected
▪ In second trimester, AFP, uE3, inhibin and HCG are all normal (can be
misleading)
o Many are detected via antenatal ultrasound
o Diagnosis confirmed via amniocentesis or CVS → allows karyotyping
o Can also do non-invasive prenatal testing (NIPT)
• After birth: chromosomal analysis
What is Edward’s syndrome and how common is it?
· Trisomy 18; 1 in 14,000 births
· Many will die in infancy, but prolonged survival is possible
What is Edward’s syndrome associated with?
Exomphalos/ Omphalocele
What investigations do you do for Edward’s syndrome?
• Antenatal screening
o Biochemicals
▪ In first trimester, HCG and PAPP-A are lower
▪ In second trimester, AFP and uE3 also decrease, inhibin A is normal or
slightly low
o Many are detected via antenatal ultrasound
o Suspicion should also be raised if polyhydramnios present
o Diagnosis confirmed via amniocentesis or CVS → allows karyotyping
o Can also do non-invasive prenatal testing (NIPT)
• After birth: chromosomal analysis
What is Noonan’s syndrome?
- Autosomal dominant inherited syndrome
* Autosomal dominant inheritance in up to 50% of cases → check FH
What is the epidemiology of Noonan’s syndrome?
- Incidence: ~1 in 1500/2500
* Often thought of as the ‘male Turner’s’
What is the aetiology of Noonan’s syndrome?
• Typically caused by gain-of-function mutations of multiple genes in the Ras/mitogenactivated protein kinase (MAPK) signal transduction pathway. Some genes implicated
include: (usually a defect in gene on chr 12)
o PTPN11 (most common mutation, found in 50-60% of patients)
o SOS1 (10-15% of patients)
o RAF1
o KRAS
What is the prognosis of Noonan’s?
Prognosis is mainly dependent on type and severity of cardiac disease
What are the clinical features of Noonan’s?
Short stature
Ptosis
Chest deformity
Congenital heart defects- PS, septal defects, HOCM, ToF
• Unusual facial features
o Wide-spaced and down-slanting eyes with vivid blue/blue-green irides
o Low-set, posteriorly-rotated ear
o Inverted triangular-shaped face with small chin
o Broad or webbed neck
• Lymphatic dysplasia
o M: Cryptorchidism and delayed puberty
• F: Delayed puberty (mean onset of menarche 14 years)
• Easy bruising or bleeding
What investigations would you do for Noonan’s?
• ECG o Likely will show wide QRS complexes, left axis deviation • Echocardiogram • FBC • Clotting studies
What is the management of Noonan’s?
- Initial assessment to determine complications associated with the disease
- If cryptorchidism → refer to urology, may need surgery (usually via an inguinal or scrotal incision)
- If congenital heart anomalies → cardiovascular assessment and evaluation for surgery
- If poor growth → may need recombinant GH
What is the aetiology of Pataus?
o Most commonly due to nondisjunction
o Robertsonian translocation accounts for small proportion
▪ Usually chromosome 13 translocates with 14
o Mosaicism also accounts for small proportion
▪ Usually have less severe symptoms
• Risk factor: increasing maternal age
What are the clinical features of Pataus?
Microcephaly/ Holoprosencephaly
Meningomyelocele
Developmental delay
Cutis aplasia/ scalp defect
Micropthalmia + eye defects
Cleft lip/ palate
polydactyly
Septal defects
PCKD
Rocker bottom feet
Omphalocele
What is the management of Patau’s?
Supportive treatment, focusing on treating life-threatening complications
