Genetic Conditions Flashcards
(22 cards)
Cystic fibrosis prevalence
1 in 25 Caucasian are carriers
Most common autosomal recessive disorder in the uk
Incidence of babies born with CF in uk is 1 in 2500
Genetics of CF
Mutation in the CFTR gene on chromosome 7
There are >2000 mutations of this gene
Classified into 6 classes
Pathophysiology of CF
CFTR produced produced by this gee regulates the movement of chloride and sodium ions across epithelial cell membranes
When the protein is not working correctly, chloride becomes trapped in cells
Without proper movement of chloride, water cannot hydrate the cellular surface
This leads the much covering the cells become dehydrated, thick and sticky
Thick mucus flatted the cilia so they cannot remove pathogens from the airway
CF Resp system
Build up of mucus throughout the body
A combination of decreased mucocillary clearance and an altered ion transport allow for bacterial colonisation of the respiratory tract
These pathogens cause an overwhelming inflammatory response
Chronic infection and this respective inflammatory response can lead to airway destruction
Pathophysiology CF pancreas
Pancreatic ductal cells from the epithelial lining of the tubes that deliver enzymes to the duodenum they rely on the CFTR protein to function properly
In CF, these tubes become blocked it’s mucus. Digestive enzymes build up in the pancreas causing inflammation. Supplementatal digestive enzymes are taken with meals to compensate for
The pancreas is unable to make enough bicarbonate to neutralise stomach acid which can contribute to GI symptoms
What does pancreatic insufficiency often lead to
CF related diabetes
Pathophysiology of liver
Normal secretion and function of bile is affects
Bile becomes more sticky and causes irrational and inflammation in the ducts
The ducts can be obstructed by the presence of gallstones.
The irrational and inflammation can lead to fibrosis (scarring) and cirrhosis (irreversible damage )
Pathophysiology of intestines
Undirected food from lack of enzymes in the intestines can cause pain, cramping, gas and wither loose greasy floating stools or constipation and blockages
Lack of bile prohibits the breakdown of fat.
Pre conception care of CF
Info about sexual and reproductive health issues in early adolescence
Offer specialist psychological advic in relation to fertility including family planning, pregnancy and infertility
Health review and optimisation for people planning a pregnancy under named consultant alongside specialist team
Avoid conception whitest having a acute infection
Nutritional advice reduces malnutrition and improves neonatal weight
Review of meds
Offer referral to clinical genetics for genetic counselling
Offer screening for carrier status to the biological father
Pre implantation genetic testing
Relevant for couples where both carry a genetic mutation
In IVF or ICSI is used, but the e,Bryson are tested for genetic mutations before being implanted into the uterus. A single cell is. Taken when the embryo is 6 cells or 8 cels of size
Aims to avoid need to terminate pregnancies affected by genetic conditions
Success rate per cycle is - 20%
Antenatal care
Offer consultant led care pathway
MDT. Approach to health optimisation
If did not have pre conception care, offer referral to clinical genetics at booking appointments for - genetic counselling, offer of partner carrier status testing, discussion of diagnostic fetal testing options if partner is a carrier
Refer to consultant anaesthetist for early reve
Chroniojic villus testing
Fine need,e insterted inter abdominal LH to obtain a piece of placenta tissue to test fetal dna
Ultrasound scan used to guide needle
11-14weeks
Risk of miscarriage is 0.5% following procedure
Amniocentesis
Amniotic fluid sample obtained
Fetal dna tested for genetic condition
15-20 weeks
Pcr
Heat and enzymes are used to multiple deconstruct and reconstruct the dna so can detect genetics variations
Microarray
DNA microarrays are opeslides that are printed with thousands of tiny spots in defined position with each spot contains a known dna sequence of gene
Sample compared with a refernce sample to detect genetic differences
Karyotyping
Pairing and ordering all the chromosomes providing genome wide snapshot if an individuals chromosome
Staining used to reveal structural features on glass life under microscaope
Ongoing AN cat differentiating symptoms
Nasal stuffiness - may be due to nasal obstruction could be sleep apnoea
Dyspnoea may be due to excaberations of CF
Urinary incontinence may be due to constant airway clearancepelvic floor exercises
Health promotion
Medical adherence to optimise health
Optimise lung function
Pelvic floor exercise
High energy diet
Regular assessment of bmi
Fetal growth USs in 3rd trimester
Labour and birth
Choose of vaginal or c/s dependent on lung function
Avoid GA if possible
Regional suitable and may reduce cardiac work
Entonox less effective
Consider hdu
Avoid prolonged pushing and valasav manoeuvre in second stage of labour
25% of pregnancies in CF population end in preterm birth either spontaneous or thereuptic usually due to deteriorating maternal pulmonary function
Persisting hypoxia the delevopmeng of ankle swelling or headaches un the context of poor lung function are grave signs
Postnatal
Care in hdu if impaired lung function are
Early mobilisation and physiology to increase air entry
Support balancing baby care and self care and priotise rest
Support and enable breastfeeding in keeping with maternal wishes ensure adequate additional caloric intake
Contraception - dept injection impanon mire a coil combined pill
Neonatal care
Genetic testing if stays is unknow or routing NBBS
Preterm car if indicate - promote breast milk feeding thermoregulation avoidance of hypoglycaemia etc
Note - mec ileum warrants testing for cr even if antenatl screening was NAD
Mec lieu’s affects 1 in 7 babies with CF
