Lecture 7: Cystic Fibrosis/Familial Aortic Anneurysm/Hypercholestemia Flashcards
Cystic Fibrosis (3)
- most frequent, life-limiting, autosomal recessive* d/o in caucasian population
- incidence: 1 in 2,000 -3,500
- frequency of carriers in US is 1:25
Pulmonary Symptoms of CF (3)
- result from obstruction of tubular structures by viscous secretions
- sx begin in first year of life (classic type)
- respiratory symptoms most prominent features
- chronic cough due to airway resistance
- recurrent pneumonia
- nasal polyps
- nose bleeds
- chronic sinusitis (ex. resistance to first line abx)
- structural changes in airway: cysts, abscesses, fibrosis
- hemoptysis (coughing up blood) in acute infection -> iron deficiency anemia
* occur in first few months of life - commonly isolated pathogens
- s. aureus
- pseudomonas aeruginosa
Pancreatic and GI symptoms (6)
- complications from exocrine pancreatic insufficiency are other major clinical components of classic CF
- prod. abnormal secretions result in obstruction and dilation of pancreatic ducts -> fibrosis and formation of cysts
- affected children show bulky, fatty, and malodorous stools (steatorrhea)
- develop significant failure to thrive and hypoproteinemia - long term symptoms: deficiency of fat soluble vitamins, A, D, E, K
- diabetes melitis
- male infertility (azoospermia): congenital absence of vas deferens
Genetics CF (6)
- caused by mutation on CFTR gene on chromosome 7q31.2
- CF transmembrane conductance regulator is an adenosine triphosphate (ATP) dependent chloride channel
- located in apical membrane of epithelial cells - CFTR gene codes for membrane protein that regulates chloride channels in epithelial cells
- autosomal recessive
- delegations, non-sense mutations, frameshift mutations, and splice site mutations of the CFTR gene result in the complete absence of functional CFTR
- more than 1,000 mutations in CFTR gene have been reported
Most frequent mutation in CF (4)
- Delta-F508
- loss of 3 nucleotides CTT causes the final gene production to have a deletion of the amino acid phenylalanine (f) at position 508 of CFTR protein
- altered CFTR protein is processed intracellularly and disintegrates in the cell’s proteasome complex
- majority (60%) caucasian patients with classic CF are homozygous for the mutation p.f508del.
Pathophysiology CT: respiratory
- viscous mucous in the small respiratory pathway
- disrupts mucociliary clearance
- favors bacterial growth
- recurring infections of the respiratory tract
Pathophysiology CT: Pancreas
- secretion that is deficient in chloride, bicarbonate, and water
- blocks pancreatic ducts
- significantly decreased the solubility of secretory proteins (enzymes)
Pathophysiology CT: sweat
- disrupted reabsorption of sodium chloride leads to abnormal composition of sweat
- abnormally salty: diagnostics significance
Diagnosis CT (3)
- may be established in individuals with at lease one phenotypic feature and a mutation in CFTR as evidences by one of the following
a. presence of TWO mutations in the CFTR gene
b. TWO abnormal quantitative sweat chloride tests
- by the quantitative pilocarpine iontophoresis method
c. TWO trans epithelial nasal potential difference measurements
Management/Tx/Surveillance CF (10)
- replacement of pancreatic enzymes and deficient vitamins
- dietary supplement - bronchodilators
- ABX
- mucous thinning agents
- pain management
- anti-inflammatory agents
- respiratory therapy
- lung transplant
- chest physiotherapy
- immunizations
Aneurysm
abnormal, localized dilation of an artery
Aortic Dissection
life threatening condition in which blood from the vessel lumen passes through a tear in the intima into the medial later and spreads along after
Three Layers Aortia
- intima (inner)
- media
- Aventia (outer)
Acute Aneurysm Dissection
- caused by CT defects that result in a loss of smooth muscle fibers and elasticity, thereby weakening the aorta and other arteries
Familial thoracic aortic aneurysm (2)
- presents at an earlier age than sporadic thoracic aneurysm
- diagnosis based on the presence of dilation and/or dissection of the thoracic aorta and a positive family hx that is not attributable to marfan syndrome or other CT tissue abnormalities
Aortic Aneurysm (5)
- most asymptomatic
- pt. may be aware of pulsatile mass
- symptoms related to compression of neighboring structures by an expanding aneurysm
- first suspected when dilation of a vessel is observed on chest or abdominal radiographs
- wall is calcified - may also be discovered by careful palpation during physical exam
Complications of thoracic aneurysm
may compress the
- trachea
- mainstem bronchus
- resulting in a cough, dyspnea, pneumonia
Aortic Dissection Overview (2)
- thought to arise from a circumferential or transverse tear in the intima layer of the vessel wall that allows blood from the lumen
- 2 types
- Type A
- Type B