Genetics Flashcards
What is the genotype of Turner’s syndrome?
45 X
What percentage of genotype 45 X will result in miscarriage?
95%
How is Turner syndrome detected antenatally?
USS shows foetal oedema of neck, hands or feet
Or a cystic hygroma - lympathic malformation
What is the incidence of Turner syndrome?
1 in 2500 females
Describe the features of Turner syndrome
Short stature Neck webbing/thick neck Valgus forearms Delayed puberty Ovarian dysgenesis Hypothyroidism Recurrent otitis media Normal intellectual function usually
What is the treatment of Turner syndrome?
Growth hormone
Oestrogen replacement
What is the genotype of Klinefelter syndrome?
47 XXY
What is the incidence of Klinefelter syndrome?
1-2 per 1000 males
What are the features of Klinefelter syndrome?
Infertility Hypogonadism with small testes Pubertal development may appear normal Gynaecomastia Tall stature Usually normal intelligence
What is the change that causes Down syndrome?
Trisomy 21
What is the most common genetic cause of severe learning difficulties?
Down syndrome
What is the incidence of Down syndrome?
1 in 650
How can Down syndrome be diagnosed antenatally?
Maternal blood sample
Amniocentesis
Chorionic villus sampling
What are the typical facial features in Down syndrome?
Round face and flat nasal bridge
Epicanthic folds
Small mouths and protruding tongue
Small ears
What are the non-facial features of Down syndrome?
Short neck Single palmar crease Duodenal atresia Hypotonia Congenital heart defects - AVSD Hirschsprung’s disease
What process do we use to detect the genetic abnormality in Down syndrome?
FISH
What should children with Down syndrome be screened regularly for?
Visual and hearing impairments
Coeliac Disease
Hypothyroidism
Atlanto-axial instability
How is cystic fibrosis inherited?
Autosomal recessive
What is the commonest genetic mutation of cystic fibrosis?
Delta F508
DMD is inherited through which pattern?
X linked recessive
Which inheritance pattern is most common in haemophilias?
X linked recessive
What is the inheritance pattern of PKU?
Autosomal recessive
The most common type of polycystic kidney disease has which inheritance pattern?
Autosomal dominant
Sickle cell anaemia has which inheritance pattern?
Autosomal recessive
