Cystic Fibrosis, other AR diseases, mascular dystrophies and other X link disorder Flashcards
Most common lethal disease in Caucasian population
Cystic fibrosis
Cystic fibrosis inheritance mode
AR
CFTR function
Encodes an ATP gated CL- channel that secretes CL- in lungs and GI tracts and reabsorbs CL- in sweat glands
Cystic fibrosis defect and mutation
CFTR gene on ch 7
Deletion of phe508 / AR
Cystic fibrosis pathophysiology
Misfolded protein accumulates in RER–>decreased CL- and (water) secretions–> increased sodium and water reabsorption via epithelial sodium channels–> THICK MUCUS SECRETIONS INTO LUNGS AND GI. Also more negative transepithelial potential negative
CL- concentration in sweat in cystic fibrosis
> 60meq/L
Diagnosis of cystic fibrosis
- CL> 60 meq/L in sweat
- Contraction alkalosis and hypokalemia (Na/water losses and concomitant renal K+/H+ wasting) –> just like LOOP DIURETICS
- increased immunoreactive trypsinogen (newborn screening)
Cystic fibrosis treatment
- N-acetylcysteine
- Dornase alfa (aerolized)
- pancreatic enzymes for insuficiency
- Azithromycn (as anti-inflammatory agent)
- chest physiotherapy
- albuterol
N-acetylcysteine mechanism of action
Loosens mucus plugs (cleaves disulfide bonds within mucus glycoprotein)
Cystic fibrosis complications
- Recurrent pulmonary infections (Pseudomonas in adolescence, S. aureus in early infancy )
- Chronic bronchitis and bronchiectasias (reticulonobular pattern on CXR)
- Pancreatic insufficiency, malabsorption and steatorrhea
- NASAL POLYPS
- Meconium ileus in newborn
- Infertility in males (absence of vas deferens, absent sperm spermatogenesis may be unaffected)
- Clubbing nails
- Subinfertility in females (amenorrhea, abnormally thick cervical mucus
- biliary cirrhosis
10 liver disease
Dormase alfa
DNAase to clear leukocyte debris
CFTR ch
7
Albinism mode of inheritance
AR
Infantile polycystic kidney disease (ARPKD) mode of inheritance
AR
Cystic fibrosis mode of inheritance
AR
Glycogen storage disease modes of inheritance
AR
Hemochromatosis mode of inheritance
AR
Kartagener mode of inheritance
AR
All mucolysaccharides are AR EXCEPT
Hunter syndrome
Phenylketonuria mode of inheritance
AR
Sickle cell anemia mode of inheritance
AR
Thalassemias mode of inheritance
AR
Wilson disease mode of inheritance
AR
All shingolipidoses are AR except
Fabry disease
Briton agammaglobulinemia mode of inheritance
XR
Wiskott-Aldrich syndrome mode of inheritance
XR
Fabry disease mode of inheritance
XR
Ocular albinism mode of inheritance
XR
Lesch-Nyhan mode of inheritance
XR
Duchenne and becker mascular dystrophy mode of inheritance
XR
Hunter syndrome mode of inheritance
HR
Hemophilia A and B mode of inheritance
XR
Ornithine transcarbamylase deficiency mode of inheritance
XR
Which gene has the largest coding region of any human gene
Clinical correlation
Dystrophin gene (DMD) Increased chance of spontaneous mutation
DMD
Dystrophin gene
Which gene has the largest coding region of any human gene
Clinical correlation / mode of inheritance
Dystrophin gene (DMD) Increased chance of spontaneous mutation XR
Dystrophin/primary tissue of action
It helps anchor muscle fibers, primary in skeletal and caridac muscle
Dystrophin function
Anchor muscle fibers
Connects intracellular cytoskeleton (actin) to the transmembrane proteins α and β dystroglycan , which are connected to extracellular matrix
Duchenne type of mutation
X-linked frameshift mutation
Duchenne pathophysiology
X-linked frameshift mutation–> truncated dystrophin protein –>accelerated muscle breakdown and inhibited muscle regeneration
Gower maneuver
Patients use upper extremity to help them stand up
Duchenne clinical manifestations
- Weakness begins in pelvic gridle muscles and progress superiorly
- Pseudohypertrophy of calf muscle (fibrofatty replacement of muscle
- Gower maneuver
- Dilated cardiomyopathy
- Waddling gait
Duchenne age of onset
Before 5
Most common cause of death in Duchene
Dilated cardiomyopathy
Becker dystrophy mutation
X-linked point mutation in dystrophyn gene (no frameshift)
Becker age of onset
Adolescence or early adulthood
Duchenne vs becker dystrophy
Becker is less severe
Becker has point mutation
Becker onset in adolescence or early adulthood (duchenne before 5)
Loss of dystrophin results in……
It can cause …
Myonecrosis
Both duchenne and Becker
Duchenne diagnosis
- high CK and aldolase
- Western blot
- biopsy to confirm
Myotonic type 1 muscular dystrophy gene
DMPK
Myotonic type 1 muscular dystrophies pathophysiology
AD –> CTG repeat expansion in the DMPK gene—> abnormal expression of myotonin protein kinase
Myotonic type 1 muscular dystrophy symtoms
- Myotonia 2. Muscle wasting 3. Frontal balding 4. Cataracts 5. Testicular atrophy 6. Arrythmia
G6PD mode of inheritance
XR
Fragile X syndrome major gene
FMR1 gene
Fragile X pathophysiology
X-linked defect affecting methylation and expression of FMR1 gene
Trinucleotide repeat disorder CGG
Most common cause of genetic intellectual disability
Down syndrome
Second most common cause of genetic intellectual disability
Fragile syndrome
Trinucleotide repeat disorder of fragile x syndrome
CGG
Fragile X syndrome findings
- Post pubertal macroorchidism (enlarged testes)
- Long face with large jaw
- Large everted ears
- Autism
- Mitral valve prolapse
Trinucleotide repeat expansion diseases feature
Anticipation: increased severity and decreased age of onset in successive generation
Trinucleotide repeat expansion diseases
- Fragile x syndrome - CGG
- Friedreich ataxia - GAA
- Huntington - CAG
- Myotonic Dystrophy - CTG
Trinucleotide repeat expansion diseases
- Fragile x syndrome - CGG
- Friedreich ataxia - GAA
- Huntington - CAG
- Myotonic Dystrophy - CTG
Friedreich ataxia trinucleotide
GAA
Huntington disease trinucleotide
CAG
Myotonic dystrophy trinucleotide
CTG
Recurrent pulmonary infections in CF - bugs(Pseudomonas in adolescence, S. aureus in early infancy )
Pseudomonas in adolescence
S. aureus in early infancy
Duchenne gait
Waddling gait
Trinucleotide repeat expansion diseases
- Fragile x syndrome - CGG
- Friedreich ataxia - GAA
- Huntington - CAG
- Myotonic Dystrophy - CTG