QUESTION 35) 1) Loss-of-function mutations of which of the listed genes can contribute to several types of carcinomas? A. FGFR B. Myc C. Cdk4 D. Mdm2 E. p21 1 points QUESTION 36 1. Which of the following genotype frequencies of A,A,, A,A2, and A,A2, respectively, do not satisfy the Hardy-Weinberg principle? A. 0.25, 0.50, 0.25 B. 0.49, 0.42, 0.09 C. 0.01, 0.18, 0.81 D. 0.64, 0.35, 0.01 E. 0.36, 0.48, 0.16

 

 

Answer

1: P21

2: D option ( 0.64,0.35,0.01)

Q 1: example of cancers by loss of function of P 21. loss of P21 causes various cancers

Colorectal cancer : p21 downregulation associates with p53 detection and the development of metastasis and poor survival,

p21 downregulation inversely correlates with high microsatillite instability irrespectively of the p53 status

Decreased p21 expression in dysplastic ACFs and adenomas; decreased p21 associated with lymph node and liver metastasis, and poor survival

Tonsillar carcinoma : p21 overexpression strongly associates HPV-positive tonsillar SCC with favourable prognosis

Gastric cancer : Those with p21-positive and p53-negative cancers had significantly higher survival curves; all p21- and p53-positive cases were TGFβ1 positive

Breast cancer : C94T of CDKN1A (Arg → Trp) with inability of p21 to inhibit CDK activity but intact ability to bind PCNA and promote CDK-cyclin association

Breast, gastric and ovarian cancers: Loss of p21 expression along with increased p53 detection associated with poor prognosis and decreased overall survival

Cervical adenocarcinoma : p21 expression correlated with favourable prognosis

Bladder carcinoma : p21 is a positive marker for invasive cancers, but is a negative prognostic marker in superficial cancers

Q2:

hardy weinbergs calculation formulla

A² +2AB+ B² = 1

in the above question, only D option ( 0.64,0.35,0.01) does not follow the hardy weinbergs principle.

B² = 0.01

B = 0.1

A+B = 1

A+ 0.1 = 1

A = 1-0.1 = 0.9

now

0.9*0.9 + 2*0.9*0.1 +0.1*0.1 =1

0.81+ 0.18+ 0.01 = 1

which means

A1A1 = 0.81 but in question it is 0.64 hence does not follow hardy weinbergs principle