STRUCTURAL CHROMOSOMAL SYNDROMES
STRUCTURAL CHROMOSOMAL SYNDROMES
- Down syndrome (Trisomy 21): 1 in 1000 births
- Facial: flat occiput, oval face, low set eyes, prominent epicanthic folds
- Single plantar creases, hypotonia
- Congenital heart diseases
- Developmental delay
- Life expectancy >60 years in >50%
- Edwards syndrome (Trisomy 18): 1 in 6000 births
- Facial: low set eyes, malformed ears, receding chin, protruding eyes, cleft lip/palate
- Short sternum with widely separated nipples
- Finger contractures: index finger overlaps the third digit
- Umbilical/inguinal hernias
- Rocker bottom feet
- Rigid body with limb flexion
- Developmental delay
- Life expectancy ~10 months
- Patau syndrome (Trisomy 13): 1 in 10000 births
- Facial: microcephaly, small eyes, cleft lip/palate
- Hand flexion contractures
- Polydactyly with narrow fingernails
- Brain malformations
- Heart malformations
- Polycystic kidneys
- Usually fatal within the first year
- Cri-du-chat syndrome: 1 in 50000 births
- Deletion of chromosome 5p
- Facial: microcephaly, epicanthic folds, moon-shaped face
- Cat-like cry
- Developmental delay
- Fatal in the first year
- Turner syndrome: 1 in 2000 female births
- Female phenotype
- Facial: ptosis, nystagmus
- Webbed neck, short stature
- Wide-spaced nipples, broad chest
- Coarctation of the aorta, left heart defects
- Lymphoedema of legs
- Klinefelter syndrome: 1 in 1000 male births
- XXY chromosomes
- Often undetected until adult infertility
- Decreased libido, reduced facial hair
- Gynaecomastia
- Increased breast cancer risk
- Small firm testes
- Associated: hypothyroidism, diabetes, asthma
- Fragile X syndrome: 1 in 4000 males, 1 in 6000 females
- X-linked
- Low IQ
- Large testes
- Facial: high forehead, large jaw, long ears, asymmetry
- Associated: autism, anxiety, ADHD, OCD
- Consider unexplained developmental delay