Genetics Flashcards
What chromosomal abnormality causes Patau’s syndrome?
Trisomy 13
What are the features of Patau’s syndrome?
- Cardiac defects = VSD, PDA, dextrocardia
- Microcephaly and brain defects
- Microphthalmia (small eyes)
- Other eye defects
- Cleft lip/palate
- Polydactyl
- Omphalocele / Gastroschisis (abdominal wall defects)
What chromosomal abnormality causes Edward’s syndrome?
Trisomy 18
What are the features of Edward’s syndrome?
- LBW
- Small mouth/chin
- Low-set ears
- ‘Rocker-bottom’ feet
- Overlapping fingers
- Intellectual disability
- Cardiac, renal and GI abnormalities
- Omphalocele / Gastroschisis (abdominal wall defects)
What chromosomal abnormality causes Down’s syndrome?
Trisomy 21
What are the features of Down’s syndrome?
- Characteristic facies
- Hypotonia and short neck
- Single palmar crease
- ‘Sandal gap’ on feet
- Short stature
- Upslanting palpebral fissures
- Flat occiput
- Congenital heart defects in 40%
- Omphalocele / Gastroschisis (abdominal wall defects)
What genetic abnormality causes Noonan’s syndrome?
Mutated RAS/Mitogen Activated Protein Kinase
What are the features of Down’s syndrome?
- Webbed neck
- Trident hairline
- Pectus excavatum
- Short stature
- Pulmonary stenosis
- Low IQ - most common cause
What genetic abnormality causes Prader-Willi syndrome?
Lacks paternal 15q
What genetic abnormality causes Angelman’s syndrome?
Lacks maternal 15q
What are the features of Prader-Willi syndrome?
- Hypotonia
- Hyperphagia
- Almond-shaped eyes
- Fat, floppy, flaccid
- Hypogonadism
- Obesity (in later childhood)
- Epicanthal folds
- Flat nasal bridge + upturned nose
- Learning disability
What are the features of Angelman syndrome?
- Cognitive impairment
- Ataxia
- Epilepsy
- Abnormal facial appearance
- Myoclonic seizures
What chromosomal abnormality causes Turner’s syndrome?
45 X
What are the features of Turner’s syndrome?
- Lymphoedema of hands/feet in neonate
- Short stature, spoon-shaped nails
- Wide carrying angle
- Thick or webbed neck
- Infertility
- Bicuspid aortic valve > Aortic coarctation
- ESM over aortic valve
- Delayed puberty / Infertility
- Hypothyroidism
- Omphalocele / Gastroschisis (abdominal wall defects)
What chromosomal abnormality causes Klinefelter’s syndrome?
47 XXY
What are the features of Klinefelter’s syndrome?
- Infertility
- Hypogonadism (small testicles)
- Gynaecomastia
What genetic abnormality causes Fragile X syndrome?
CGG trinucleotide repeat expansion mutation (fragile) to the FMR1 gene