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Clinical cases

Clinical cases

Question 1 of 14

1

All of the following about hereditary breast and ovarian cancer are true except?

Select one of the following:

  • Autosomal recessive inheritance

  • BRCA 1 and BRCA 2 normally maintain genomic integrity by acting as a tumor suppressor gene and regulating DNA repair, transcription transactivation and the cell cycle

  • 2 hit hypothesis- Somatic LOF by the second allele occurs by loss of heteozygosity, intragenic mutation or promoter hypermethylation

  • Founder effect seen in Ashkenazi Jews

  • Germ line mutation of BRCA2 is associated with male breast cancers (6-14%)

Explanation

Question 2 of 14

1

Familial hypercholesterolemia is characterized by all of the following except?

Select one of the following:

  • Autosomal Dominant inheritance

  • Mutation of LDL receptor found in 59% of French Canadian with familial hypercholesterolemia

  • LDL-R binds apoB100 and apoE

  • decreased LDL cholesterol

  • Management is mainly low fat high carbohydrate diet with 3 classes of drugs: bile sequestrants (Cholestyramine resin), HMG CoA reductase inhibitors and nicotinic acid

Explanation

Question 3 of 14

1

All of the following about G6PD deficiency are true except

Select one of the following:

  • X-linked recessive inheritance

  • G6PD is the first enzyme in HMP shunt critical for generating NADPH which is required to regenerate glutathione

  • Rare symptomatic females - due to skewing of X chromosome inactivation

  • G6PD B- is less severe than G6PD A-

Explanation

Question 4 of 14

1

A 25 year old African-American man is given anti-malarial prophylaxis for a trip to West Africa. Over the next week he develops increasing fatigue. On Physical exam there are no abnormal findings. Lab studies show a hematocrit of 30% and peripheral blood smear shows red blood cells with numerous Heinz bodies. There is a family history of this disorder, with males but not females, affected. What is the most likely diagnosis

Select one of the following:

  • OTC deficiency

  • Sickle cell disease

  • Pyruvate dehydrogenase deficiency type 1

  • None of the above

Explanation

Question 5 of 14

1

A 30 year old woman has felt a mass in her right breast for 6 months. On physical exam there is a 5 cm mass in the right breast and it is firm, non tender with lymphadenopathy. A fine needle aspiration is performed and cytologic exam shows carcinoma cells. Right mastectomy with axillary lymph node dissection is performed and microscopic exam shows a poorly differentiated carcinoma that is negative for estrogen and progesterone receptors and negative for HER2/neu. One axillary node shows micrometastases. Her 32 year old sister is found to have a similar lesion. Which is the following is the most likely risk factor for this woman's breast cancer?

Select one of the following:

  • BRCA 1 mutation

  • loss of p53

  • Both of the above

  • none of the above

Explanation

Question 6 of 14

1

All of the following about Hereditary hemochromatosis are correct except

Select one of the following:

  • Autosomal recessive with reduced penetrance

  • HFE mutation

  • 90-95% of patients are homozygous for a Cys282Tyr mutaion

  • Mutant HFE interferes with hepcidin signaling resulting in stimulation of enterocytes and macrophages to release iron

  • Hepcidin is synthesized in liver and released to block further iron absorption when iron supplies are adequate

  • Males are protected against this condition

Explanation

Question 7 of 14

1

46 year old man who has had worsening arthritis and swelling of his feet for the past year. On exam he has rales audible in all lung fields. A CXR showed cardiomegaly and pulmonary edema. Lab studies showed Hgb of 13, Hct of 39.1% MCV 86fl, platelet count of 255,000/ul and WBC count 5920/ul. His serum iron is 406 microgram/ml, with iron binding capacity of 440 micrograms/ml and ferritin 830 ng/ml. What is the most likely diagnosis

Select one of the following:

  • Cystic fibrosis

  • Hereditary hemochromatosis

  • None of the above

Explanation

Question 8 of 14

1

All of the following about Hemophilia are true except?

Select one of the following:

  • Both Hemophilia A and B are X-linked recessive

  • Factor 9 - Most common mutation is an inversion deleting the carboxyl terminus of factor 9

  • Factor 9 - severe hemophilia during childhood that spontaneously resolves at puberty as factor 9 levels nearly normalize

  • Therapy is replacement of the factor that is deficient

Explanation

Question 9 of 14

1

All of the following regarding HPNCC are true except

Select one of the following:

  • Autosomal Dominant inheritance

  • Mutation in MLH1, MSH2) DNA mismatch repair gene mutation

  • Microsatellite instability occurs in 15-20% of HNPCC tumors

  • Microsatellite instability induced frame shift mutations in the transforming growth factor receptor II gene (TGFBetaR2)

Explanation

Question 10 of 14

1

All of the following are true regarding NIDDM except?

Select one of the following:

  • Multifactorial inheritance

  • TCF7L2 significantly associated with NIDDM in Icelandic population and Pro12Ala mutation in PPARG in Finnish and Mexican Americans

  • More prone to develop ketoacidosis

  • HbA1c > 6.5% is more important that the actual glucose levels

Explanation

Question 11 of 14

1

A 57 year old man is found comatose. On exam he has decreased skin turgor. Lab studies show a blood glucose of 780 mg/dl. Urinalysis reveals no ketosis or proteinuria, but there is 4+ glucosuria. What is the most likely diagnosis?

Select one of the following:

  • IDDM

  • NIDDM

  • Combination of both because of hyperglycemia

Explanation

Question 12 of 14

1

24 hour old male baby is comatose and on lab studies shows Hyper ammonia, hypo citrullemia and urine showed orotic aciduria. Most likely diagnosis

Select one of the following:

  • CPS I deficiency

  • CPS II deficiency

  • OTC deficiency

  • None of the above

Explanation

Question 13 of 14

1

All of the following are true about Retinoblastoma except?

Select one of the following:

  • Autosomal Dominant - LOF mutation on chromosome 13

  • Isodisomy is the most common type of mutation

  • Nearly half the mutations occurs at CpG dinucleotides (C --> T transition)

  • Unilateral disease in hereditary

Explanation

Question 14 of 14

1

All of the following for Tay-Sachs disease are true except?

Select one of the following:

  • Autosomal recessive inheritance

  • Hexosaminidase A is a lysosomal enzyme made of HEXA + HEXB genes, Hexosaminidase A in the presence of activator protein, removes the N-terminal GalNAc from the ganglioside

  • Curable disorder

  • Infantile - onset is characterized by neurological deterioration at 3-6 months of age and Juvenile onset usually manifests between 2-4 yrs of age and also characterized by neurological deterioration

  • Have normal levels of hexosaminidase B

Explanation

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