Genetic Conditions Flashcards
Turners syndrome
45 X
- girl with only one X chromosome
physical features of turners syndrome
short stature
webbed neck
widely spaced nipples
renal abnormality in turners
horseshoe kidney
cardiac abnormality in turners
bicuspid aortic valve – aortic stenosis
coarctation of aorta
what is achondroplasia
dwarfism
what gene is defective in achondroplasia
FGFR3
what is Downs Syndrome
Trisomy 21
dysmorphic features in Downs Syndrome
prominent epicanthic folds single palmar crease short stature hypotonia brachycephaly (small head with flat back)
complications of Downs syndrome
learning disability recurrent otitis media / deafness hypothyroidism cardiac abnormalities - ASD, VSD, PDA, tetralogy of fallot atlantoaxial instability
screening test for down Syndrome
offered to all women - identifies women at higher risk who could go on to have more invasive testing to give a definitive diagnosis
screening takes place between 11 - 14 weeks gestation:
- USS for nuchal translucency ( > 6mm abnormal and could suggest downs)
- Material Beta HcG (higher levels = higher risk)
- A-PAPPA (Lower levels = higher risk)
women with risk greater than 1 in 150 are offered invasive testing
diagnostic test for Down syndrome
chorionic villous sampling (done before 15 weeks)
amniocentesis (done after 15 weeks)
average life expectancy for child with Downs syndrome
60 years
Klinefelter syndrome
47 XXY
- male with an extra X chromosome
physical features of Klinefelter syndrome
usually normal until puberty. Then can develop
- gynaecomastia
- wide hips
- tall
- lack of secondary sexual characteristics
- small testicles
gonadotrophin levels are elevated but testosterone is low
inheritance of cystic fibrosis
autosomal recessive
gene defect in cystic fibrosis
defect in CFTR gene due to mutation in delta F508 on chromosome 7
features of cystic fibrosis
meconium ileus in neonatal period recurrent chest infections malabsorption - steatorrhoea / failure to thrive Type 1 diabetes short stature delayed puberty / male infertility
how is Cystic fibrosis diagnosed
chloride sweat test
- sweat chloride will be abnormally high
what is Patau syndrome
trisomy 13
- small eyes
- clef palate
- polydactyly (extra fingers / toes)
- rocker bottom feet
what is Edwards syndrome
trisomy 18
- rocker bottom feet
- low set ears
- clenched hands
majority die shortly after birth
what is Prader Willi syndrome
deletion of proximal arm chromosome 15 from father (imprinting)
- insatiable hunger – leads to obesity
- hypogonadism
- hypotonia
- learning difficulties
what is Angelman Syndrome
deletion of proximal arm of chromosome 15 from mother (imprinting)
- fascination with water
- happy demeanor
- widely spaced teeth
- delayed development + learning difficulties
what is Kartagners syndrome
primary ciliary dyskinesia
- dextrocardia
- bronchiectasis
inheritance of Duchenne Muscular dystrophy
X linked recessive
- +Ve Gowers sign - uses hands to get up off floor
Features of Fragile X
most common inherited cause of neuro-developmental delay
low set ears
long face, large head
features of Williams Syndrome
elfin face very friendly + social child short stature elongated philtrum neonatal hypercalcaemia supravalvular aortic stenosis
features of Noonan syndrome
‘male turners syndrome’
- webbed neck
- pulmonary stenosis
- short stature
- pectus excavatum
risk of mother having child with Downs syndrome if
- 40 years old
- 45 years old
40 years = 1 in 100 risk
45 years = 1 in 50 risk
what is androgen insensitivity
X linked recessive condition
male genotype (46 XY) but phenotypically female
- primary amenorrhoea
- groin swelling – undescended testes
