Exam 1 Disorders

Question 1

Achondroplasia

Answer 1

-Autosomal dominantly inherited disorder
-The most common skeletal dysplasia
-Short arms and legs, large head, and characteristic facial features
-Intelligence and life span are usually normal
~99% of cases due to one of two common mutations
Prevalence: 1:26,000-1:28,000 live births

Question 2

Marfan Syndrom

Answer 2

• has a high degree of variation in expressivity

- Systemic disorder of connective tissue

Question 3

BRCA gene

Answer 3

• gene that has been shown to have a high correlation with breast and ovarian cancer when mutated
• this is an example of incomplete penetrance as not all people with BRCA

Question 4

Cystic Fibrosis

Answer 4

• autosomal recessive disorder which created a dysfunctional CFTR receptor (Cl- channel part of the ABC ATPase family)
• one of the most commonly inherited diseases
• effects primarily the pulmonary and digestive system
• may also be cause by uniparental disomy

Question 5

Sickle cell anemia

Answer 5

• autosomal recessive inheritance

- most common in the african american population

Question 6

hemophilia

Answer 6

-x linked recessive inheritance
-bleeding disorder caused by deficiency in factor 8 or 9
-

Question 7

duchenne muscular dystrophy

Answer 7

• x linked recessive

- progressive disease in skeletal muscle

Question 8

incontinentia pigmenti

Answer 8

-x linked dominant inheritance

Question 9

MELAS

Answer 9

-mitochondrial inheritance

-

Question 10

myotonic dystorphy

Answer 10

-this was given as an example of anticipation (a process where a disease gets more severe with each subsequent generation)

Question 11

fragile X syndrome

Answer 11

• most frequent inherited cause of intellectual disability
• Caused by CGG repeat expansion in FMR1 gene on X chromosome
• this is another example of anticipation
• due to the expansion of a trinucleotide repeat

Question 12

mosaic downs syndrome

Answer 12

• this is a situation where not all of a persons cells have 3 chromosome 21’s
• features and severity of the disease depend on the proportions of cells in each tissue type that carry the mutation

Question 13

pallister killian

Answer 13

-this is a caused by tetrasomy 12 and is only found in mosaic form as a full tetrasomy 12 is not compatible with life

Question 14

prader willi syndrome

-must know features

Answer 14

• Features: hypotonia, intellectual disability, hyperphagia (pathological overeating)
• Caused by lack of expression from genes in the critical region that are normally only expressed from the paternal allele

Question 15

Angelmans syndrome

-must know features

Answer 15

• Features: severe intellectual disability, movement disorder, and seizures
• Caused by lack of expression from genes in the critical region that are normally only expressed from the maternal allele.

Question 16

cleft lip

Answer 16

• this is used as an example of recurrence risk

- someone with bilateral cleft lip has a greater chance of passing on cleft lip than someone with unilateral cleft lip

Question 17

Breast Cancer

Answer 17

• used as an example of association studies
• if you have a family member that has had breast cancer, your risk of developing it will double
• there are also may environmental factors that will effect that chance

Question 18

Alzheimers

Answer 18

• another example of association studies
• if you have a first degree family member with it, your risk doubles
• apolipoprotein E has been studied extensively as a factor in alzheimers