Genetic Disorders II
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- The mutation in TSC1 is on which chromosome? What does it encode?
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1. 9q
2. Hamartin - The mutation in TSC2 is on which chromosome? What does it encode?
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1. 16p
2. Tuberin - GTPase - Are most TSC new mutations of inherited mutations?
- New
- TSC problems are involved in a mutation involving the function of what kind of genes?
- Tumor suppressor genes
- What is the clinical triad of TSC?
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1. Mental retardation
2. Epilepsy
3. Adenoma sebaceum - What would be a better term to describe a adenoma sebaceum?
- Angiofibroma - mixed up population of cells which are vascular smooth muscle cells and skin cells that become confused and causing little bumps.
- How many TSC patients exhibit the classical triad?
- 1/3
- What are seven other features of TSC that are the most important ones?
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1. Subependymal calcifications
2. Sz
3. Olfactory hamartomas
4. Ashleaf spots/confetti nodule - need a Wood's lamp - hypopigmented
5. Adenoma sebaceum
6. Shawgreen patches
7. Ungral fibromas - Adenoma sebaceum is often confused with what?
- acne
- Subependymal lesions are often described as...
- Candle gutterings
- What are TSC symptoms usually seen in kids?
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1. Cardiac rhabdomyomas
2. Renal angiomyolipoma
3. Renal cysts
4. Pulmonay cysts
5. Liver hamartomas
6. Fibromas on their gumline
7. Renal hamartomas - Under histological examination of a rhabdomyoma, how is it described?
- Spiderlike appearance
- A retinal exam of someone with TSC is described as....
- Mullberry-like flat lesion
- What are the three common characteristics of OI?
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1. Osteopenia
2. Osteoporosis
3. Skeletal deformities - What is the MOI for OI?
- Autosomal dominant mutation affecting Type I collagen.
- What is the most common type of OI? When is its onset?
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1. Type 1
2. Childhood or adulthood - What are the clinical features of OI?
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1. Excessive bone fragility
2. Easy bruising, bone deformity
3. Hearing loss - What is characteristic of OI (I and II)?
- Blue to grey sclera
- Which OI type leads to infant death?
- OI II
- Is the MOI of OI II usually AD or AR?
- AD
- What is the hallmark of OI II?
- Extreme bone fragility - in utero fractures
- Which disorder can you see ballotable brains?
- OI II - almost non-existant skulls
- What features are most common to most variants of Ehlers-Danlos Syndrome?
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1. Marked skin hyperextensibility
2. Poor wound healing
3. Very stretchy skin
4. Excessive vulnerbility to trauma and bruising
5. Joint hyperlaxity - What is the MOI of Vascular EDS?
- AD
- What is the usual cause of death in Vascular EDS?
- Ruptured abdominal aneurysm
- How do you tell an aneurysm from vascular EDS from arteriosclerosis??
- The vessels with arteriosclerosis usually are hard unlike vessels in vascular EDS.
- The mutation in vascular EDS is in what gene?
- Type III collagen: COL3A1
- Where can you find type III collagen?
- Blood vessels and intestine
- What are the common mutations involving Type III collagen in vascular EDS?
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1. Decreased rate of synthesis of pro alpha-1 chains for Type III
2. Decreased rate of secretion of Type III procollagen
3. Synthesis of abnormal type III collagen - What is the MOI for kyphoscoliosis EDS?
- AR
- What is mutated in kyphoscoliosis EDS?
- Lysyl hydroxylase
- What is the MOI for arthrochalasia EDS?
- AD
- What is the MOI for dermatosparaxis EDS?
- AR
- What type of collagen is affected in arthrochalasia and dermatosparaxis EDS?
- Type I collagen
- What is defective in arthrochalasia EDS?
- COL1A1 and COL1A2 which makes them resistant to peptidase cleavages.
- What is defective in dermatosparaxis EDS?
- The enzyme procollagen-N-peptidase - necessary for COL1A1 and COL1A2 cleavage.
- What is the MOI for classic EDS?
- AD
- What is defective in classic EDS?
- Type V collagen: COL5A1 and COL5A2 (30% to 50%)
- Which two EDS are AR?
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1. Kyphoscoliosis
2. Dermatosparaxis - What is the defect in Marfan Syndrome?
- Fibrillin (FBN 1)
- Most of the gene mutations in Marfan's are of what type?
- Missense mutations
- What is Marfan's until proven otherwise.
- Bilateral ectopic lentis
- Dolichocephaly
- Marfan's Syndrome
- Supraorbital prominence
- Marfan's Syndrome
- Ectasia of the dural sac
- Marfan's Syndrome
- Arachnodactyly
- Marfan's Syndrome
- High arched palates
- Marfan's Syndrome
- Aortic root disection and aortic disection
- Marfan's Syndrome
- Tay Sachs predominantly affects...
- CNS neurons
- Neimann-Pick predominantly affects....
- CNS neurons and macrophages (50/50)
- Gaucher predominantly affects...
- Macrophages
- What is the defective enzyme in Tay-Sachs?
- Hexosaminidase A alpha
- What is the defective enzyme in Sandoff?
- Hexosaminidase A beta
- What accumulates in Tay-Sachs?
- GM2 gangliosides
- What accumulates in Sandoff
- GM2 gangliosides
- What is defective in Niemann-Pick disease?
- Sphingomyelinase
- What type of Niemann-Pick disease is most prominent?
- A
- What accumulates in Niemann-Pick disease?
- Sphingomeylin
- What is the defect in Gaucher disease?
- Glucocerebrosidase
- What accumulates in Gaucher disease?
- Glucocerebroside
- What is the age of death in Tay-Sachs?
- 2-5 years
- What is the age of death in Niemann Pick disease?
- Less than 3 years
- Hypotonia is an important symptom in which lysosomal storage disorder?
- Niemann Pick disease