Genetics III Flashcards

1
Q

What mutation is associated with Marfan’s syndrome?

A

An Autosomal dominant Fibrillin-1 gene mutation (p.85)

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2
Q

Describe some complications and symptoms associated with Marfan’s.

A

Pectus excavatum, hypermobile joints, arachnodactyly, cystic medial necrosis of aorta- aortic incompetence and dissecting aortic aneurysms, floppy mitral valve, subluxation of lenses (p.85)

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3
Q

Describe the condition of Multiple Endocrine Neoplasias (MEN).

A

Three distinct autosomal dominant syndromes (1,2A,2B) characterized by familial tumors of endocrine glands including those of the pancreas, parathyroid, pituitary, thyroid, adrenal medulla (p.85)

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4
Q

What genetic mutation is associated with MEN2A and MEN2B?

A

Ret gene mutation (p.85)

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5
Q

Describe the findings of Neurofibromatosis type 1 (von Recklinghausen’s disease)

A

Caf_ au lait spots, neural tumors, Lisch nodules (pigmented iris hamartomas), skeletal disorders (scoliosis), and optic pathway gliomas (p.85)

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6
Q

What is the genetic mutation associated with Neurofibromatosis type 1?

A

Autosomal dominant mutation on the long arm of chromosome 17 (p.85)

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7
Q

Describe the findings associated with Neurofibromatosis type 2.

A

Bilateral acoustic schwannomas, juvenile cataracts (p.85)

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8
Q

What is the genetic mutation associated with Neurofibromatosis type 2?

A

An autosomal dominant mutation of the NF2 gene on chromosome 22 (p.85)

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9
Q

What are the clinical findings associated with tuberous sclerosis?

A

Facial lesions (adenoma sebaceum), hypopigmented ash leaf spots on skin, cortical and retinal hamartomas, siezures, mental retardation, renal cysts and renal angiomyolipomas, cardiac rhabdomyomas, increased incidence of astrocytomas (p.85)

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10
Q

What is the genetic mutation and inheritance of tuberous sclerosis?

A

Autosomal dominant condition with incomplete penetrance and variable presentation (p.85)

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11
Q

What are the clinical findings in von Hippel-Lindau disease?

A

Hemangioblastomas of the retina/cerebellum/medulla; the majority of patients develop bilateral renal cell carcinomas and other tumors (p.85)

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12
Q

What is the genetic mutation and inheritance of von Hippel-Lindau disease?

A

Autosomal dominant condition associated with the deletion of the VHL gene (a tumor suppressor gene) on chromosome 3. Results in constitutitive expression of HIF (transcription factor) and activation of angiogenic growth factors (p.85)

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13
Q

Name 10 autosomal recessive diseases.

A

1.) albinism; 2.) ARPKD; 3.) cystic fibrosis; 4.) glycogen storage diseases; 5.) hemochromatosis; 6.) mucopolysaccharidoses (except hunter’s); 7.) PKU, 8.) sickle cell anemias; 9.) sphingolipidoses (except Fabry’s); 10) thalassemias (p.86)

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14
Q

Describe the genetic mutation an defect associated with cystic fibrosis.

A

An autosomal recessive defect in CFTR gene on chromosome 7 (commonly a deletion of Phe508). Mutation often causes abnormal protein folding, resulting in degredation of the channel before reaching the cell surface. CFTR channel actively secretes Cl- from sweat and a defective channel causes secretion of abnormally thick mucus that plugs the lungs, pancreas, and liver (p.86)

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15
Q

What are the clinical manifestations of cystic fibrosis?

A

Recurrent pulmonary infections (Pseudomonas, S. aureus), chronic bronchitis, bronchiectasis, pancreatic insufficiency (malabsorption and steatorrhea), nasal polyps, meconium ileus in newborns (may present as failure to thrive), infertility in males due to bilateral absence of vas deferens, fat soluble vitamin deficiencies (p.86)

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16
Q

How do you diagnose and treat cystic fibrosis?

A

Diagnose by chloride sweat test; treat with N-acetylcysteine to loosen mucous plugs (it cleaves disulfide bonds within mucous glycoproteins) (p.86).

17
Q

Name 10 X-linked recessive diseases.

A

1.) Bruton’s agammaglobulinemia, 2.) Wiskott-Aldrich syndrome; 3.) Fabry’s disease; 4.) G6PD deficiency; 5.) Ocular albinism; 6.) Lesch-Nyhan syndrome; 7.) Duchenne’s and Becker muscular dystrophy; 8.) Hunter’s syndrome; 9.) Hemophilia A and B; 10.) Ornithine transcarbamoylase deficiency (p.86)

18
Q

What is the genetic mutation associated with Duchenne’s muscular dystrophy?

A

X linked frameshift mutation - deletion of the dystrophin gene (p.86)

19
Q

What is the genetic mutation associated with Becker’s muscular dystrophy?

A

X linked mutated dystophin gene; less severe than duchenne’s (p.86)

20
Q

Describe the onset and symptoms of Duchenne’s.

A

Weakness begins in pelvic girdle muscles and progresses superiorly. Onset before 5 years of age (p.86)

21
Q

What does a muscle biopsy in a patient with Duchenne’s reveal?

A

Fibrofatty replacement of muscle (p.86)

22
Q

How do you diagnose muscle dystrophies?

A

By increased CPK and muscle biopsy (p.86)

23
Q

What are the functions and characteristics of the dystrophin gene?

A

Longest known human gene with an increased rate of spontaneous mutation. It helps anchor muscle fibers, primarily in skeletal and cardiac muscle (p.86)

24
Q

What is the genetic mutation and inheritance of Fragile X Syndrome?

A

X linked defect affecting the methylation and expression of the FMR1 gene; it is the second most common cause of genetic mental retardation (after Downs) and is caused by a trinucleotide repeat of CGG (p.87)

25
Q

What are the clinical findings in Fragile X syndrome?

A

Macroorchidism, long face with large jaw, large everted ears, autism, mitral valve prolapse (p.87)