Genetics Flashcards
What is Patau’s Syndrome?
Trisomy 13 (third extra non-sex chromosome 13)
What are the S/S of Patau’s Syndrome?
- Microcephaly
- Microphthalmia (small eyes) / other eye defects
- Cleft lip/palate
- Polydactyly
- Scalp lesions
- Omphalocele / gastroschisis
What are the investigations of Patau’s Syndrome?
- USS analysis in 2nd trimester
- Chromosomal analysis from amniocentesis/cffDNA (NIPT)
- Karyotyping
> No other specific tests for dx
What is the management of Patau’s Syndrome?
Palliative care: (most babies will die within first few days)
- 80% die in the first month of life
- 90% by 1y
+ Counselling and support
What are the complications of Patau’s Syndrome?
- Kidney defects
- Spinal defects
- Infections
- Intellectual disability
- Motor disorder
What is Edward’s Syndrome?
Trisomy 18
(third extra non-sex chromosome 18)
What are the S/S of Edward’s Syndrome?
- Micrognathia / small mouth/chin
- Low-set ears
- Rocker bottom feet
- Overlapping fingers
- Intellectual disability
- Omphalocele / gastroschisis
What are the investigations for Edward’s Syndrome?
- USS analysis in 2nd trimester
- Chromosomal analysis from amniocentesis/cffDNA (NIPT)
- Karyotyping
> No other specific tests for dx
What is the management of Edward’s Syndrome?
Many will die in infancy but prolonged survival is possible
- MDT approach (OT and PT, nursing care)
- NG tube
- Counselling and parental support
What are the complications of Edward’s Syndrome?
- Cardiac abnormalities
- Feeding difficulties
- Aspiration pneumonia
What is Noonan’s Syndrome?
- Autosomal dominant
- Chromosome 12
- Normal karyotype (affects M and F)
- Penetrance varies greatly (from lethal prenatally to minimal morbidity)
What are the S/S of Noonan’s Syndrome?
- Webbed neck
- Pectus excavatum
- Short stature
- Pulmonary stenosis
- Trident hairline
What are the investigations for Noonan’s Syndrome?
1st line:
- ECG (wide QRS, giant Q waves, left axis deviation)
- Echo (CHDs)
Consider:
- Bloods: FBC, coagulation profile
- Molecular genetic testing
- Abdominal USS (splenomegaly)
- Renal USS (malformations)
What is the management of Noonan’s Syndrome?
- Correction of CHDs
- Recombinant growth hormone
- Refer to urology for cryptorchidism
What are the complications of Noonan’s Syndrome?
Cardiac abnormalities
What is Prader-Willi syndrome?
Imprinting disorder affecting paternal copy of chromosome 15 (lack of PWS region on chr15)
- Lack of paternal PWS region on chr15 = PWS
- Lack of maternal PWS region of chr15 = Angelman syndrome (cognitive impairment, ataxia, epilepsy, abnormal facial appearance)
What are the S/S of Prader-Willi syndrome?
- Hypotonia
- Hypogonadism
- Obesity
- Almond-shaped eyes
- Hyperphagia
- Flat nasal bridge and upturned nose
- Learning disability
What are the investigations for Prader-Willi syndrome?
- USS analysis in 2nd trimester
- Chromosomal analysis from amniocentesis/cffDNA (NIPT)
- Karyotyping
What is the management of Prader-Willi syndrome?
- Management of feeding and obesity (e.g. lock cupboard)
- Cryptorchidism surgery
- Hormone treatment (GH supplements if evidence of growth failure)
- Psychological – CBT, SSRIs
What are the complications of Prader-Willi syndrome?
- Obesity
- T2DM
- Metabolic syndrome
- Psychosis
What is Turner’s Syndrome?
Genetic defect in females resulting from the complete or partial absence of an X chromosome (45X)
What cardiac defects are associated with Turner’s Syndrome?
- Bicuspid aortic valve (ESM)
- Coarctation of the aorta
What are the S/S of Turner’s Syndrome?
- Neonatal lymphoedema of hands/feet/cutis laxa
- Neck webbing
- Wide carrying angle
- Broad chest with widely spaced nipples (shield chest)
- High pigmented naevi
- Hypoplastic nails
- Short fourth metacarpal
- Signs of ovarian failure - amenorrhoea, infertility
- Failure of breast development (normal pubic hair development)
- Short stature
- Congenital malformations: horseshoe kidneys, ovarian dysgenesis
What are the investigations for Turner’s Syndrome?
Antenatal:
- Amniocentesis or CVS and karyotype analysis if dx suspected (nuchal cystic hygroma / horseshoe kidney / left-sided cardiac abnormalities / non-immune foetal hydrops)
Chromosomal studies:
- Karyotype confirmation, confirmation of presence of possible Y chromosomal material (Y-centromeric probe), differentiation from Noonan syndrome (phenotypically very similar)
Bloods:
- Increased LH and FSH confirm ovarian failure
