Disorders

Question 1

Huntington’s Disease

Answer 1

Prevalence: 1 in 20,000
Inheritance Pattern: Autosomal Dominant
Symptoms: Loss or motor control, dementia, psychiatric disorder
Gene/Cause: Trinucleotide repeat CTG or CAG
Prognosis - death within 15-20 years of diagnosis
Other Notes - suicide rate is 5-10 times the normal rate

Question 2

Myotonic Dystrophy

Answer 2

Prevalence: 1 in 8000
Inheritance Pattern: Autosomal Dominant
Symptoms: cardiac arrhythmias, testicular atrophy, insulin resistance, cataracts
Gene/Cause: mutations in DMPK - a kinase on chromosome 19 - expanded tri repeat
Prognosis:
Other Notes: expansion of the repeat creates an mRNA that stays in the nucleus and causes a gain of function effect resulting in abnormaly formed proteins

Question 3

Fragile X

Answer 3

Prevalence:
Inheritance Pattern:
Symptoms:
Gene/Cause: high concentration of CG in area (repeat mutation) at FMR1
Prognosis:
Other Notes:Repeats of 5-40 = normal, 55-200 normal but maybe a learning disability
200+ = Fragile X

Question 4

Hypophospatemic Rickets

Answer 4

Prevalence:
Inheritance Pattern:
Symptoms: bone deformities, short stature, dental anomalies
Gene/Cause: low renal phosphate reabsorption, low vitamin D, increased serum alkaline phosphatases and calcification
Prognosis:
Other Notes:

Question 5

Lesch Nyhans

Answer 5

Prevalence: 1 in 380,000
Inheritance Pattern:
Symptoms: involuntary muscle movement, flailing of limb, self mutilation, caffeine high
Gene/Cause: over production of uric acid due to defective hypoxanthing phosphoribosyl transferase (HPRT) causes accumulation of Uric acid
Prognosis:
Other Notes:

Question 6

G6PDH deficiency

Answer 6

Prevalence: undefined
Inheritance Pattern: X linked recessive
Symptoms: spontaneous hemolysis resulting in jaundice
Gene/Cause: low levels of Glucose 6 phosphate dehydrogenase (prevents Ribose 5 Phosphate production and NADPH generation)
Prognosis: - avoid known triggers and be ok
Other Notes: provides some protection against malaria

Question 7

Hemophilia B

Answer 7

Prevalence: 1 in 20,000
Inheritance Pattern: X linked recessive 
Symptoms: difficulty clotting
Gene/Cause: defective Factor IX
Prognosis:
Other Notes:

Question 8

Hemophilia A

Answer 8

Prevalence: 1 in 4500
Inheritance Pattern: X linked recessive
Symptoms: easy bruising, difficulty clotting
Gene/Cause: defective Factor VIII
Prognosis:
Other Notes:

Question 9

Duchenne’s Muscular Dystrophy

Answer 9

Prevalence: 1 in 4000 males
Inheritance Pattern: X linked recessive
Symptoms: muscle weakness, delayed walking, sitting and standing, cardiomyopathy
Gene/Cause: mutation in gene that codes for DYSTROPHIN, muscle fibers weaken and are poorly anchored, muscle fibers die and are replaced with adipose or connective tissue
Prognosis: DMD - death at 20, Becker MD - death by 40’s
Other Notes: Becker’s Muscular Dystrophy occurs later with less severe symptoms

Question 10

Down Syndrome

Answer 10

Prevalence:
Inheritance Pattern:
Symptoms:
Gene/Cause:
Prognosis:
Other Notes:

Question 11

Marfan

Answer 11

Prevalence:
Inheritance Pattern:
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Gene/Cause:
Prognosis:
Other Notes:

Question 12

Lynch Syndrome

Answer 12

Prevalence:
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Gene/Cause:
Prognosis:
Other Notes:

Question 13

Beta Thalassemia

Answer 13

Prevalence:
Inheritance Pattern:
Symptoms:
Gene/Cause:
Prognosis:
Other Notes:

Question 14

PKU

Answer 14

Prevalence:
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Gene/Cause:
Prognosis:
Other Notes:

Question 15

Spinal Muscular Atrophy

Answer 15

Prevalence:
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Gene/Cause:
Prognosis:
Other Notes:

Question 16

Sickle Cell Anemia

Answer 16

Prevalence:
Inheritance Pattern:
Symptoms:
Gene/Cause:
Prognosis:
Other Notes:

Question 17

Red Green Color Blindness

Answer 17

Prevalence: not noted
Inheritance Pattern: X linked recessive
Symptoms: unable to distinguish red and green
Gene/Cause:
Prognosis: 
Other Notes: