Unit 2 (Step 1)

Front 1

Ehlers-Danlos Syndrome

Back 1

Faulty collagen synthesis causing:
1. Hyperextensible skin
2. Tendency to bleed (easy bruising)
3. Hypermobile joints
TYPE III collagen most freq affected.
6 types. Inheritance & severity vary. Can be AD or AR. May be associated w/ joint dislocation, berry aneurysms, organ rupture.

Front 2

Osteogenesis Imperfecta

Back 2

Genetic bone disorder (brittle bone ds) caused by a variety of gene defects.
Most common form is AD w/ abnorm type 1 collagen, causing:
1. Multiple Fractures w/ minimal trauma; may occur during birth process
2. Blue Sclerae due to the translucency of the CT over the choroid
3. Hearing loss (abnorm middle ear bones)
4. Dental imperfections due to lack of dentin

May be confused w/ child abuse.
Type II is fatal in utero or in neonatal period
Incidence is 1:10,000

Front 3

Leber's hereditary optic neuropathy

Back 3

Mitochondrial myopathy.
Degeneration of retinal ganglion cells and axons. Leads to acute loss of central vision

Front 4

Achondroplasia

Back 4

Cell signaling defect of fibroblast growth factor receptor 3 (FGF). Results in dwarfism; short limbs, but head and trunk are normal size. Associated w/ advanced paternal age.

Front 5

Huntington's Disease

Back 5

Depression, progressive dementia, choreiform mvmts, caudate atrophy, and decreased levels of GABA & ACh in brain.
Symptoms manifest in affected individuals bw ages 20-50.
Gene located on chromosome 4; trinucleotide repeat disorder (CAG).
"Hunting 4 food"

Front 6

Marfan's syndrome

Back 6

Fibrillin gene mutation -> CT disorder affecting skeleton, heart, & eyes.
Findings: tall w/ long extremities, pectus excavatum, hyperextensive joints, & long, tapering fingers & toes (arachnodactyly); cystic medial necrosis of aorta -> aortic incompetence and dissecting aortic aneurysms; floppy mitral valve. Subluxation of lenses

Front 7

Neurofibromatosis type 1 (von Recklinghausens's Disease

Back 7

Findings: cafe-a-lait spots, neural tumors, Lisch nodules (pigmented iris hamartomas). Also marked by skeletal disorders (eg scoliosis), optic pathway gliomas, pheochromocytoma, and increased tumor susceptibility.
on long arm of chromosome 17.
"17 letters in von Recklinghausen"

Front 8

Neurofibromatosis type 2

Back 8

Bilateral acoustic neuroma, juvenile cataracts. NF2 gene on chromosome 22
"type 2 = 22"

Front 9

Duchenne's Muscular Dystrophy

Back 9

X-linked frame-shifted mutation -> deletion of dystrophin gene -> accelerated muscle breakdown. Weakness begins in pelvic girdle muscle & progress superiorly. Pseudohypertorphy of calf muscles due to fibrofatty replacement of muscle; cardiac myopathy.
Use of Gowers' maneuver, requiring assistance of upper extremities to stand up. onset <5 yo

"Duchenne's = Deleted Dystrophin"
Dystrophin gene (DMD) is the longest known human gene - increased rate of spontaneous mutation. Dystrophin helps anchor muscle fibers, primarily in skeletal and cardiac muscle.
Diagnose muscular dystrophies by increased CPK and muscle biopsy

Front 10

Becker's Muscular Dystrophy

Back 10

X-linked mutated dystrophin gene. Less severe than Duchenne's. Onset in adolescence or early adulthood.
Diagnose muscular dystrophies by increased CPK and muscle biopsy

Front 11

Fragile X Syndrome

Back 11

X-linked defect affecting the methylation & expression of the FMR1 gene.
Associated w/ chromosomal breakage.
2nd most common cause of genetic mental retardation (after Down).
Findings: macro-orchidism (enlarged testes), long face w/ a large jaw, large everted ears, austism, mitral valve prolapse.

Trinucleotide repeat disorder - CGG

"Fragile X = eXtra-large testes, jaw, ears"

Front 12

Trinucleotide repeat expansion diseases

(4 answers)

Back 12

huntington's (cag)
myoTonic dystrophy (cTg)
fraGile x syndrome (cGg)
friederich's ataxia (gaa)

"HUNTINGton's disease, MYotonic dystrophy, FRIEDreich's ataxia, fragile X syndrome =
TRY (TRInucleotide) HUNTING for MY FRIED eggs (X)"