EXAM 3: Pathology of genetic diseases & developmental malformations

Question 1

Which TORCH disorders has calcification and which one has saber shin?

Answer 1

• Saber shin is caused by Congenital Syphilis (Syphilitic osteochondritis and periostitis affects all bones causing saddle-nose deformities along with saber shin)

• Calcifications seen in Toxoplasmosis
(Intracranial calcifications)
-Microcalcifications can also be seen with Congenital Varicella-Zoster.

Question 2

What does Toxoplasma present with?

Answer 2

1) Intracranial calcification
2) Chorioretinitis (inflamed choroid and retina)
3) Hepatosplenomegaly (enlarged spleen/liver)
4) Fever
5) Jaundice
6) Skin rash
7) encephalitis

• Only occurs when mother is infected during pregnancy
• 1/3 of infected mothers give birth to infected infants
• Can cause abortion or stillbirth
• Treatment= combined sulfadiazine and pyrimethamine

Question 3

What does Congenital Syphilis present with?

Answer 3

1) osteochondritis and periostitis = Saber shin (bowed legs) & Saddle nose
2) liver/heart/lung fibrosis b/c of gummas
3) Hutchinson’s teeth

Question 4

Which TORCH disease is currently most common in United States?

Answer 4

• MOST common cause of congenital infection in the US is Cytomegalovirus (CMV) due to multiple modes of transmission
• Leading cause of mental retardation in US
• Can also cause pneumonia and hepatitis in immunosuppressed patients (AID)
• Can also cause retinitis and blindness & colitis w/ diarrhea in AIDS patients

Question 5

3. Which TORCH disorder has the cat as the definitive host?

Answer 5

TOXOPLASMOSIS

• Human infection begins when ingestion of cysts in undercooked meat/ contact w/ cat feces (contains cysts)
• Can also be transmitted transplacentally from mother to fetus (Congenital Toxoplasmosis)
• Caused by protozoan tissue parasite Toxoplasma gondii that normally causes a subclinical infection w/ mild lymphadenophathy in immunocompetent, but devastating in infants in-utero & immunosuppressed.
• The cysts differentiate in gut & invade gut wall & infect macrophages where numerous tachyzoites are produced.

Question 6

Which of the TORCH disorders belong to the herpes family and which do not?

Answer 6

• Herpes family: CMV, Herpes Simplex Virus 1 & 2, Varicella & Zoster
• Not HBV (species of the Orthohepadnavirus), Toxoplasma, or Rubella.

Question 7

Which TORCH disorders have a basophilic vs Eeosinophilic (acidophilic) inclusions?

Answer 7

• (CMV) Cytomegalic Inclusion Disease= characterized by multicuncleated giant cells w/ prominent BASOPHILIC intranuclear inclusion affecting many organs (brain liver and kidneys)
• Intranuclear inclusions Neonatal HERPES Infection = characterized by vesicular rash with pink/red (eosinophilic) ACIDOPHILIC (cowry bodies) inclusions

Question 8

6. Know the causes of congenital syphilis and what is syphilis?

Answer 8

• An infected woman can transmit the spirochete to fetus after 3rd month of pregnancy. Unless treated promptly, late abortion, stillbirth, or multiple fetal abnormalities results

• In perinatal & infantile syphilis, a diffuse rash w/ bullae develops w/ sloughing of epithelium of palms & soles. These lesions contain multiple spirochetes
• Syphilitic osteochondritis & periostitis affects all bones causing saddle-nose deformities & saber shin
• Infantile syphilis causes liver, heart & lung fibrosis due to GUMMA (Syphilitic Gumma of the heart) formation
• Late - occurring congenital syphilis is char by triad of:
• interstitial keratitis
• Hutchinson’s teeth
• 8th nerve deafness
• Diagnosis is by identifying spirochetes in early lesions by darkfield examination.
• Serologic test include VDRL & RPR (rapid plasma regain: Best non-specific) detect presence of antibodies to cardiolipin from beef hearts.
• Specific serologic test includes the FTA-ABS (fluorescent treponemal antibody absorbed test: expensive & takes longer) Involves use of treponemal antigens & test for antibodies in patient’s serum.

Question 9

Which disease overall can be involved in TORCH?

Answer 9

• The congenital infectious agents:
T: Toxoplasma-A protozoan parasite.
O: “Other”-Syphilis, Varicella, HIV, HBV.
R: Rubella- A Togavirus (German Measles)
C: Cytomegalovirus- A Herpesvirus
H: Herpes- Also a Herpesvirus

Question 10

Know the different routes for CMV virus?

Answer 10

1) across the placenta
2) within the birth canal
3) within mother’s milk
4) during blood transfusions & organ transplants
5) urine (baby to baby transmission)

Question 11

Most common congenital heart defects in congenital rubella syndrome?

Answer 11

• Patent Ductus Arteriosus

Question 12

What are the major components of surfactant?

Answer 12

• Surfactant is a surface active substance, rich in LECITHIN/SPHINGOMYELIN that keeps the pulmonary alveoli open and prevents collapse.
• In preparation for babies respiratory function after birth, the Alveolar type II pneumocytes begin secreting Surfactant
• Released into amniotic fluid and fills fetal lungs
• No need for prenatal respiration b/c of oxygen being delivered via placenta from mother
• Surfactant produced by fetal lungs is not required in‐utero
• L/S ratio > 2:1 = mature fetal lungs
• L/S ratio < 2:1 = risk of Hyaline Membrane Disease

Question 13

Which hormones are considered pro vs anti surfactant?

Answer 13

-ANTI‐surfactant= insulin
Insulin is suppressed in infants of diabetic mothers
High sugars stimulate insulin production from fetal pancreas

-PRO‐surfactant= cortisol, thyroxine, prolactin
Corticosteroids are used to induce formation of surfactant in the fetal lungs

Question 14

What is DES? What is another name for it and what can it cause?

Answer 14

• Diethylstilbestrol(DES)
• It is a synthetic estrogen
• Used in the past to prevent abortions in women
• Causes: a cervical hood, a T‐shaped uterus, infertility, and premature labor Associated w/ Clear Cell Adenocarcinoma of the vagina

Question 15

What drugs can cause auditory nerve toxicity leading to deafness?

Answer 15

Aminoglycoside antibiotics such as:

1) Streptomycin
2) Amikacin
3) Tobramycin

-Can cause CN VIII (Auditory Nerve) toxicity with permanent bilateral deafness and loss of vestibular function.

Question 16

What are the complications using tetracycline in pregnancy?

Answer 16

• Tetracycline & doxycycline (Vibramycin) are both antibiotics that may cause permanently stained (yellow) teeth and hypoplasia of enamel.

Question 17

Differentiate between the characteristics and physical features in Trisomy 13 ?

Answer 17

Trisomy 13 - Patau Syndrome (rare)

• Associated w/ an increased maternal age
• Associated w/ severe malformations -> rarely survive a few months

CLINICAL FEATURES:

1) Microcephaly
2) Deformed, low set ears
3) Microphthalmia
4) MR
5) CLEFT lips/palate
6) Polydactyly (extra digits) / rocker bottom feet (prominent heel bone)
7) Cardiac anomalies
8) Renal defects
9) Umbilical hernias

Question 18

Differentiate between the characteristics and physical features in Trisomy 18 ?

Answer 18

• 2nd most common autosomal disorder
• 85-90% due to nondisjunction
• Associated w/ increased maternal age
• Severe malformations - most do not live months

CLINICAL FEATURES:

1) Prominent occiput w/ low set ears
2) Severe MR
3) Micrognathia (small mouth)
4) Overlapping fingers
5) CHD
6) Renal anomalies
7) rocker bottom feet

Question 19

Differentiate between the characteristics and physical features in Trisomy 21 ?

Answer 19

• MOST common chromosomal disorders & major cause of mental retardation
• Associated w/ increased maternal age (95%)
• Due to meiotic non-disjunction, 4-5% are due to Robertsonian translocation
• At risk for systemic disorders
• 40% have CHD’s - atrial & ventricular septal defects - most common cause of death in infancy/childhood
• Atresias of the esophagus & small bowel along w/ umbilical hernias
• 10-20 fold increased risk of developing acute leukemias (ALL and AML)
• Over 40 -> develop neuropathologic changes characteristic of Alzheimer’s Dementia
• Abnormal immune responses -> predisposes them to serious infections, particularly Pneumonias

CLINICAL FEATURES:

1) FLAT facial PROFILE w/ oblique palpebral fissures, slanted eyes, & EPICENTRAL FOLDS
2) Thick protruding tongue w/ mouth usually open
3) Dysplastic ears
4) Moderate to severe mental retardation
5) Simian Crease - short broad hands
6) Hypotonia and GAP between 1st and 2nd toe

Question 20

What is another name for Trisomy 18,21, and 13 (named after the guys who coined it)

Answer 20

• Trisomy 13 - Patau Syndrome
• Trisomy 18 - Edward Syndrome
• Trisomy 21 - Down Syndrome

Question 21

What is the genetics of Cri Du chat syndrome

Answer 21

• Caused by DELETION of SHORT ARM of chromosome # 5 & affected infants up to 1 yr of age have characteristic meow-like cry.
• Usually thrive better than trisomies 13 and 18 and some survive into adulthood.
• Manifests w/ growth and mental retardation, microcephaly, short fingersm depressed nasal bridge, round face, cleft palates and gut defects

Question 22

Deficiency of what vitamin is associated with neural tube defects?

Answer 22

• Maternal folic acid (vitamin B9) deficiency has been associated with an increased incidence of Spina Bifida as well as all of the other neural tube defects

Question 23

What are the general feature of Anencephaly?

Answer 23

• The congenital absence of all or part of the brain, malformation of the ANTERIOR END of the neural tube (Anterior Neuropore)
• 2nd most common (Spina Bifida #1)
• More common in FEMALES
• Are either stillborn or die within the first few days of life
• Forebrain development is disrupted due to failure of closure of the anterior end of the neural tube (Anterior neuropore)
• The cranial vault is absent and the cerebral hemispheres are represented by a discoid mass of highly vascularized, poorly differentiated neural tissue called the Area Cerebrovasculosa, which lies on the flattened base of the skull behind two well formed and normally positioned eyes

Question 24

What is the Area Cerebrovasculosa?

Answer 24

• Poorly differentiated NEURAL tissue area, which lies on the flattened base of the skull behind two well-formed & normally positioned eyes
• Seen in Anencephaly

Question 25

What are the 4 types of Spina Bifida? (Which is the best/worst?)

Answer 25

• Spina bifida is a LOWER neuropore does not close.
• MOST common NT defect
• “POSTERIOR” vertebral arches fail to fuse

1) Occulta (BEST for patients to have) - SINGLE vertebra fails to fuse - usually has a tuft of hair and dimpling on back

2) Meningocele - occipital or lumbo-sacral sac, NO NERVE roots EXPOSED
- Diverticulum w/ fluid‐filled sac of meninges & CSF

3) Meningomyelocele - limbo-sacral mass of nerve roots meninges within it, DIMPLE in the center
- Dura, arachnoid, and neural tissue protrude from vertebral canal forming a bulge

4) Rachischisis (WORST for patients to have) - NERVE ROOTS extend out of skin (caudal equine), NO SAC, flat against skin (w/ visible spinal cord)
- Occurs when POSTERIOR neuropore of neural tube fails to close during week 4

• Moms take Folic acid to avoid NTD’s (neural tube defects)

Question 26

What is the difference between meningoencephalocele and other meningomyelocele?

Answer 26

1) Meningoencephalocele:
• A similar diverticulum of malformed CNS tissue & flattened arachnoid extending thru a defect in POSTERIOR cranium (occiput).

• The constituents of the sac are the same as for meningocele (except w/ brain tissue)

• If the ventricular cistern as well as the brain & meninges protrude from the unossified gap in the skull, the condition is termed meningohydroencephalocele.
• Not a spina bifida

2) Meningomyelocele:
• A more severe case of Spina Bifida where dura & arachnoid, as well as neural tissue protrudes from vertebral canal, forming a bulge through opening.

• A sac covered w/ skin is visible on surface, complete with trapped nerve roots, particularly those of caudal equine to be trapped in subcutaneous scar tissue.
• The spinal cord appears as a flattened, ribbon-like structure.
• Neurologic dysfunction is seen, related to structural abnormality of the cord itself & to superimposed infection that extends from thin, overlying skin.
• The patient manifests clinical defects referable to motor & sensory function in lower extremities as well as disturbances of bowel & bladder control.
• A Lumbosacral Meningocele is when meninges only protrude through opening, covered by a skin-lined sac.

Question 27

General features of **Klinefelter vs Turner syndrome? (Know that 50/50 chance material vs pateral side

Answer 27

Klinefelter’s syndrome: 47 XXY Male

• 2 or more X chromosomes, 1 or more Y chromosomes from non-disjunction
• Rarely diagnosed before puberty b/c testicular abnormality does not develop until early teens

FEATURES: lack of beard and body hair, gynecomastia, hips are FEMALE like, lack of pubic hair, testicular atrophy, INFERTILITY, long legs/arms

• Eunuchoid body habitus
• Elongated body
• Small atrophic testes and small penis
• Lack of secondary sex characteristics: deep voice, beard
• Mean IQ is lower but retardation is uncommon

Question 28

General features of Klinefelter vs *****Turner syndrome?

Answer 28

Turner’s syndrome:

• Complete or partial monosomy of X-chromosome, most common = 45 XO Karyotype (Majority cases missing an entire X)
• MOST common sex chromosome abnormality in females
• FEATURES: short stature, amenorrhea, edema b/c of lymph stasis in hands and feet, heart shaped face, coarctation of aorta, cubits valgus, streak ovaries, infertility, broad chest & widely spaced nipples, webbing of neck b/c distended lymph channels (Cystic Hygroma), low posterior hair line, pigmented nevi of skin,
• Turner’s syndrome is the single most important cause of primary AMENORRHEA
• After puberty there is failure to develop secondary sex characteristics: genitalia is INFERTILE, inadequate breast development, little pubic hair, atrophic ovaries, Ribrous Strands (STREAK OVARIES)
• Normal mental status, few exhibit mental retardation
• 50% pts develop autoantibodies against thyroid gland
• Fetal ovaries develop normally early in embryogenesis but absence of second X chromosome leads to accelerated loss of oocytes which is complete by age 2 (menopause occurs before menarche!)

Question 29

What are the General features EXTERNALLY for Turner syndrome?

Answer 29

• Short stature (rarely exceeding 150cm in height)
• Pt’s present during infancy with edema (due to lymph stasis) of dorsum of hands & feet.
• Webbing of neck due to distended lymphatic channels, producing the so-called CYSTIC HYGROMA. As they grow older, webbing can become a persistent looseness of skin on back of neck.
• Broad-shaped chest w/ widely-spaced nipples
• Pigmented nevi (sharply circumscribed & chronic lesions of skin/ mucosa) on skin of extremities & trunk
• Abnormal carrying angle of the arm, called CUBITS VALGUS.
• At puberty, there is a failure to develop normal secondary sex characteristics-the genetalia remains infantile, breast development is inadequate, there is little pubic hair.

Question 30

What are the General features INTERNALLY for Turner syndrome?

Answer 30

• Amenorrhea: MOST important cause of primary amenorrhea, accounting for ⅓ of the cases.
• CONGENITAL HEART DEFECTS are COMMON, particularly COARCTATION of AORTA & BICUSPID VALVES. Cardiovascular abnormalities are the single most important cause of increased mortality w/ Turners.
• OVARIES are reduced to atrophic, fibrous strands (streak ovaries), resulting in INFERTILITY.
• MENTAL status = NORMAL, but a few may exhibit some mental retardation.
• Approx. 50% develop autoantibodies directed against thyroid gland, & up to half develop clinically manifest hypothyroidism.
• During normal fetal development, ovaries contain 7 million oocytes. The oocytes gradually disappear, by menarche = 400,000.
• By the time menopause occurs, fewer than 10,000 oocytes remain.
• Fetal ovaries develop normally early in embryogenesis, but absence of second X chromosome leads to an accelerated loss of oocytes, which is complete by age of 2 yrs.
• Menopause occurs BEFORE menarche in other words.

Question 31

What are the lab values in Klinefelter syndrome that relate to testosterone?

Answer 31

• HYPOGONADISM is the most consistent finding, the plasma FSH levels are consistently HIGH & the testosterone levels are REDUCED.
• The pathology relates to reduced spermatogenesis & male infertility. The testicular tubules are totally atrophied, & replaced by pink, hyaline, collagenous shells. LARGE Leydig cells may contribute to atrophy.

Question 32

What the classic congenital heart defect seen in Turner syndrome?

Answer 32

• Congenital heart defects are common, particularly Coarctation of the Aorta and Bicuspid Aortic Valves.
• Cardiovascular abnormalities are the single most important cause of increased mortality in children with Turners.

Question 33

What is a cystic hygroma?

Answer 33

1) Distended lymphatic channels causing a webbing of the neck.
2) Seen in Turner syndrome
3) As infants grow older, the webbing can become a persistent looseness of skin on the back of the neck.

Question 34

What is the genetic in Huntington’s disease and what are some characteristics?

Answer 34

1. An autosomal dominant disorder that is characterized by involuntary movements of all parts of the body, with deterioration of cognitive functions, and emotional disturbances.
2. The HD gene is located in chromosome 4, that codes for the production of an altered protein “Huntingtin”, that is widely expressed throughout the body & all regions of the nervous system, by both neurons & glial tissue
   • It’s function & mechanism is unknown,
   • HD is one of the purest examples of a true autosomal completely dominant disorder (heterozygotes do not differ clinically)

Question 35

What is the genetics of Marfan’s syndrome and what organ systems are involved? What is the protein deficiency? What chromosome is the deficiency location on?

Answer 35

GENETICS: Autosomal Dominant Disorder
- Dysfunction of gene on chromosome 15 that codes for Fibrillin

• CT PROTEIN essential for maintenance of tissue structure of organs
• Tendons & vessel walls devoid of normal FIBRILLIN become loose, weak, & cannot support normal body functions
• Disorder of CT manifested by changes in skeleton, eyes, and CV system
  1) SKELETAL: slender & tall, elongated head (dolichocephalic), prominent frontal bossellation, arachnodactyly (long spider fingers), frequent luxations & spinal deformities (kyphoscoliosis)
  2) CV: dilatation of aorta (aortic aneurysm w/ exsanguination), fraying of tissues, floppy valves, valves malfunction, mitral valve prolapse & regurgitation leading to heart failure & death
• Blood separates the layers of the weakened aorta, ultimately producing dissecting aneurysms, which are also prone to rupture.
• Microscopically, there is fragmentation & loss of elastic fibers w/ abundant mutinous mucopolysaccharide deposition (CYSTIC MEDIAL NECROSIS)
• Death is most often caused by heart failure secondary to valvular dysfunction or rupture of AORTIC ANEURYSM w/ exsanguination.
  3) EYES: (Ocular) displaced lens (subluxations), cataracts, retinal detachments, blindness

Question 36

What is the genetics involved in CF?

Answer 36

• Most common autosomal recessive disease
• Almost only seen in Caucasians
• GENETICS: defect in gene that normally codes for protein forming CHLORIDE TRANSPORT CHANNEL in the cell membrane causing Cl transport defect across cell membrane leading to lack of NaCl in glandular secretions of all exocrine glands
• Secretions have less water and are viscid leading to obstruction of lumens of organs

Question 37

What organ system involved in CF?

Answer 37

• Most important glands affected: pancreas, intestines, bronchi
  1) PANCREAS: malabsorption, malnutrition, chronic pancreatitis, prevent flow of pancreatic juices

2) INTESTINE (fetal): steatorrhea, intestinal rupture and dissipation of intestinal contents throughout the abdominal cavity (meconium ileum with peritonitis)
- Stool contains undigested food, bulky, greasy, foul smelling

3) BRONCHI: bronchitis, bronchiectasis, pneumonia, honeycomb lung, lung abscesses, recurrent pulmonary infection
- MOST important complication is hyper viscosity of bronchial mucous making viscous plugs to prevent respiration
- Other: abnormal sweat, cor pulmonale, secondary biliary cirrhosis, obstructed vas deferens (sterility), clubbing of nails

Question 38

What gram (-) do CF people have to worry about

Answer 38

• Pseudomonas aeruginosa

Question 39

What is a sweat test and what disease would you use it in?

Answer 39

• Used to screen for Cystic Fibrosis
• Measures the chloride concentration that is excreted in sweat
• Due to defect Chloride channels, elevated levels of chloride will be seen in a person with CF

Question 40

What is Osteogenesis Imperfecta? what is genetics? The lamens term and what teeth malformations are seen?

Answer 40

“Brittle Bone Disease”
• A group of heritable disorders of connective tissue, caused by mutations in the gene for type 1 Collagen. (Autosomal Dominant)

• Affects skeleton, joints, teeth, sclera, skin, ligaments, & ears
• Involves MUTATIONS of COL1A1 (CHROMOSOME 17) & COL1A2 (CHROMOSOME 7) genes, which encode for chains of Type 1 pro collagen, major STRUCTURAL PROTEIN of bone.
• Mutations of COL1A1 are seen in all types of OI, & affects 3/4 of the type 1 collagen molecule
• Mutations of COL1A2 affects 1/2 of synthesized collagen molecule

• Because of the hypoplasia of the dentine and pulp, teeth are misshapen and bluish - yellow in color
*NO TREATMENT

Question 41

Which 2 disorders having to do with Hyaline Membrane Disease of newborn is directly related to charged radicals?

Answer 41

1. Retrolental Fibroplasias:

Long‐term, high [O2] can produce O2 radical—>toxicity in the eyes of newborn—>blindness

2. Bronchopulmonary Dysplasia (BPD):

-Due to HIGH [O2} & toxicity of O2 radicals
- Fibrosing condition of peribronchial & interstitial
tissue—->wall thickening

Question 42

In Hyaline Membrane Disease of the newborn which Congenital Heart Defect is related to this because of the PREMATURITY?

Answer 42

• Patent Ductus Arteriosus (PDA) due to PREMATURITY
• Mortality rate is about 50 % in infants weighing around 1000 grams.
• 24-28 weeks gestation, 20-30% in infants over 30 weeks

Question 43

What is Fragile X syndrome and what are the characteristics of fragile X?

Answer 43

• MOST common form of inherited mental retardation due to a defect on LONG ARM of X Chromosome
• 2nd only to Trisomy 21 as an identifiable cause of mental retardation
• A fragile site is a specific site is a specific locus on a chromosome that breaks easily. (Up to 50 fragile sites on autosomes sex chromosomes).
• Locus at Xq27 is associated w/ mental retardation due to a repeat of an amino acid sequence (CGG REPEAT @ FRAGILE SITE)
• Male NEWBORNS afflicted appear NORMAL, but during childhood, CHARACTERISTICS appear:
• INCREASED HEAD circumference
• Facial coarsening
• Joint hyper extensibility
• ENLARGED TESTES
• ABNORMALITIES of cardiac valves
• Mental retardation = (IQ 20-60)
• A significant proportion of AUTISTIC MALE children carry fragile X chromosome
• 80% of males who exhibit the fragile site are mentally retarded. Other 20% are clinically normal, but can transmit trait.
• Females who are known to bear the fragile X chromosome (carriers), 2/3 are intellectually normal, & other 1/3 are mentally retarded
• The fragile X is usually detected in cytogenetic preparations as a non-staining gap or constriction

Question 44

What is Duchenne Muscular Dystrophy?

What is the genetic transmission?

Answer 44

a. A SEVERE X-LIKED (only MALES AFFECTED - inherited or spontaneous) RECESSIVE Disorder of muscle caused by MUTATION of the gene DMD

b. The DMD gene codes for the protein Dystrophin, an important structural component w/in muscle tissue.
• Provides structural stability on inner surface of muscle sarcolemma
• Links subsarcolemmal cytoskeleton to exterior of cell

c. The PATHOGENESIS relates to Dystrophin-deficient muscle fibers that LACK NORMAL interaction btwn sarcolemma & extracellular matrix.

• A continuous effort at repair & regeneration early on in disease, where degenerative process eventually outweighs regenerative capacity of muscle

• Relentless NECROSIS of muscle fibers, invasion by scavenging macrophages
• Progressive fibrofatty CT

d. This ABSENCE of dystrophin permits EXCESS Ca++ to penetrate sarcolemma causing oxidative stress to muscles causing NECROSIS & CELL DEATH
e. The dead muscle fibers are REPLACED by ADIPOSE tissue & CT, & release Creatine Kinase (CK) into serum
f. END-STAGE = characterized by an almost complete LOSS of SKELETAL MUSCLE.
g. Disease characterized by progressive degeneration of muscles, particularly those of PELVIC & SHOULDER girdles
h. The MOST common non-inflammatory myopathy in children
i. Clinical weakness not detectable until about 4-5 yrs old - usually bed ridden by age 15
j. MOST common cause of death -> complications of respiratory insufficiency, cardiomyopathy/ cardiac arrhythmia

MAIN SYMPTOMS:

1) Progressive muscle weakness
2) Muscle wasting - voluntary muscles being first affected ->hips, thigh, calf then -> arms, shoulder, neck
3) Pseudohypertrophy of calf (enlargement of a muscle due to replacement of muscle fibers by fibroadipose tissue)
4) Frequent falls, difficulty walking/running
5) Fatigue
6) express variable degrees of mental retardation
7) GI dysfunction (due to degeneration of smooth muscle)
8) Positive Gower Sign

Question 45

What is GOWERS sign(+) ?

Answer 45

• Child helps himself to get up w/ upper extremities

- Rises on arms and knees, then “walks” hands to legs to stand upright

Question 46

What is the protein that is deficient in Duchenne Muscular Dystrophy?

Answer 46

• The Duchenne Muscular Dystrophy (DMD) gene codes for the protein Dystrophin, an important structural component within muscle tissue. Dystrophin provides structural stability on the inner surface of muscle sarcolemma.
• Dystrophin links subsarcolemmal cytoskeleton to exterior of cell.