Post Bacc Exam V

Question 1

Marfan Syndrome

Answer 1

• Autosomal dominant
• Mutation in fibrillin-1 (FBN1) gene
• Important in skeleton, eye, blood vessels
• Long limbs, arachnodactyly, lens displacement
• Dilation of ascending aorta

Question 2

Ehlers-Danlos Syndrome

Answer 2

• Affect collagen
• Some autosomal dominant – collagens
• Some autosomal recessive – processing enzymes (lysyl hydroxylase, peptidase)
• Afects skin, ligaments and joints
• Skin hyperextensible, joints hypermobile
• Internal problems – colon or large artery rupture, diaphragmatic hernia

Question 3

Tay-Sachs Disease

Answer 3

• Defect in α subunit of GM2 ganglioside
• Sphingolipid (found in nervous system) accumulates in various tissues
• Lysosomes balloon to large size
• Mainly in neurons of CNS
• Whirl appearance within lysosomes

Question 4

Silent Point Mutation

Answer 4

No change in protein sequence

Question 5

Missense Point Mutation

Answer 5

Change one amino acid to another

Question 6

Nonsense Point Mutation

Answer 6

Makes STOP codon

Question 7

Autosomal Dominant Inheritance

Answer 7

• Affected individual in each generation – no “skipped” generation
• One parent should be affected
• Both sexes equally affected
• Father-son transmission possible
• 1/2 children affected

Question 8

Autosomal Recessive Inheritance

Answer 8

• May not be found in previous generations – “skips a generation”
• Males + females equally affected
• 1/4 normal, 1/2 carriers like parents, and 1/4 affected

Question 9

Sex-linked Inheritance

Answer 9

• Due to X-linked genes
• Females require affected father for inheritance
• Males receive only the recessive X-linked gene

Question 10

Familial Hypercholesterolemia

Answer 10

• Mutation in LDLR gene
• Autosomal dominant – most common
• Xanthomas form
• Double the normal serum cholesterol = increased risk of heart disease

Question 11

Lysosomal Storage Disorders

Answer 11

• Specific enzymes targeted to lysosomes
• Mannose-6-phosphate added as tag
• Go to lysosome instead of being secreted
• Lysosome just keep accumulating “trash” within them

Question 12

Niemann-Pick Disease

Answer 12

• NP A & B are sphingomyelinase deficiencies
• Accumulates in nervous tissue and many organs
• Many small vesicles cause foamy appearance (due to deposition of lipids)

Question 13

Gaucher Disease

Answer 13

• Defect in glucocerebrosidase
• Gaucher cells are plump macrophages that characteristically have the appearance in the cytoplasm of crumpled tissue paper due to accumulation of glucocerebroside
• Most common lysosomal storage disorder

Question 14

Mucopolysaccharidoses

Answer 14

• Defects in ezymes that degrade glycoaminoglycans (GAGs)
• MPS I - Hurler syndrome (autosomal recessive)
• MPS II - Hunter syndrome (X-linked recessive)
• Coarse facial features, skeletal dysplasia, growth retardation, multiple organ involvement

Question 15

von Gierke Disease

Answer 15

• Hepatic glycogen metabolism disorder
• Lack of glucose-6-phosphate
• Cannot export glucose from glycogenolysis
• Hepatomegaly and renomegaly (large glycogen deposits, some fat deposition)
• Hypoglycemia
• Hyperlipidemia
• Hyperuricemia
• Xanthomas
• Failure to thrive, stunted growth (in children)

Question 16

McArdle Disease

Answer 16

• Muscle glycogen metabolism disorder
• Defect in muscle glycogen phosphorylase
• Glycogen accumulates in striated muscle (lactate levels do not increase b/c lactate isn’t formed)
• Myoglobin and creatine kinase released

Question 17

Pompe Disease

Answer 17

• Mixed liver and muscle glycogen metabolism disorder
• Defect in acid maltase
• Liver, skeletal muscle, and heart have glycogen deposits (ballooning effect; pushes muscle apart)
• Serious effect can cause massive cardiomegaly, muscle hypotonia, cardiorespiratory failure

Question 18

Alkaptonuria

Answer 18

• Inability to metabolize tyrosine properly
• Defect in homogentisate oxidase
• Homogentistic acid accumulates, excreted in urine
• Urine turns black upon oxidation
• Deposition in joint cartilage –> become brittle