Obstetric genetics Flashcards
Why would someone be referred to genetics?
FH
Diagnosis of genetic conditions
Genetic counselling (aiding decision making, increasing understanding)
What do people need to know before undergoing a genetic test
What it's being done for What happens if its positive What is it's negative False positive/false negative Implications for other family members
What are the various reproductive tests you can have?
Chronci villus sampling
Amniocentesus
Pre implantation genetic diagnosis
Non-invasive parental diagnosis/testing
What is Duchenne muscular dystrophy?
X linekddisease that is fatal in adult life.
Muscle weakness that begins in the hips, pelvis, and legs.
Difficulty standing.
Trouble learning to sit independently and walk
Describe autosomal dominant inheritance?
Each child has a 50% chance of inheriting the mutation
No skipped generations
Equally transmitted by men and woman
What recessive disorders are specific to a population?
North european cystic fibrosis
African sickle cell disease
Mediterrean/Asian- thalassaeamias
Ashkenazi jews- Tay-sachs disease
What is cystic fibrosis?
How do you diagnose CF?
A defect of the cellular chloride transport mechanism, causes lung infections, pancreatic insufficiency
Diagnosed with immunoreactive trypsin, sweat test, genotyping
More than 1000 gene mutations cause disease
What is sickle cell disease?
What are the complications of sickle cell disease?
An abnormal HB gene which means red blood cells are sickled as opposed to concave
Symptoms of sickling include pain, cold, dehydration, infections, jaundice, stroke, leg ulcers, eye and kidney problems
What is Tay-sachs disease?
A progressive genetic lysosomal storage disease. Hexoaminidase A (hex-A_ deficiency results in the build up of lipid ganglioside in the brain
Babies develop normally until 6 months where there is progressive neurological failure. It is usually fatal by 3-5 years
What screening is completed on newborn babies?
Phenyketonuria (PKU) Congenital hypothyroidism (CHT) Sickle cell disorders (SCD) Cystic fibrosis (CF) MCADD- medium chain acyl CoA Homocyteinuria Isovaleric acidaemia Maple syrup urine disease Glutaric aciduria type 1
What is Phenylketonuria?
Babies are unable to break down phenyalanine (amino acid in protein)
Untreated babies develop serious, irreversible mental disability
Early treatment with controlled diet prevents disability
Treatment should be started by 21 days of age
What is medium chain Acyl-CoA dehydrogenase deficiency?
Babies with MCADD cannot easily breakdown fat to make energy for the body
Serious life threatening symptoms can occur quickly in babies not feedin gor unwell
Treatment is made to prevent metabolic crisis (avoid fasting and monitor frequency of meals)
Glucose polymer and IV dexstrose can also be given
What is congenital hypothyroidism?
Thyroid gland does not produce enough thyroxine. Untreated babies are left with permanent physical and mental disability unless treatment is started by day 21
