Download ppt - HEREDITARY BREAST CANCER IN DEVELOPING COUNTRIES Prof. Richard Pestell Prof. Jan Lubinski Prof. T.Rajkumar

HEREDITARY BREAST CANCER IN DEVELOPING

COUNTRIES

Prof. Richard Pestell

Prof. Jan Lubinski

Prof. T.Rajkumar

QUESTIONS TO BE DISCUSSED

• What is cancer genetic counseling?• Issues related to setting up a Hereditary

cancer programme in a developing country?

• Socio-economic issues in India and in the West.

• Financial implications in testing.• Guidelines in gene testing• What could be the take home message.

Assessing the Genetic Risks of Cancer

• If the family history reveals one or more of the following features, then a further assessment is warranted:

cancer in two or more close relatives multiple primary tumors in the same individual bilateral cancer in paired organs an earlier-than-usual onset of cancer a specific constellation of tumors that comprise a known

cancer syndrome

• If one of these features are found in the individual's own or family history, familial or hereditary factors should be considered and further evaluated.

Cancer Risk Counseling

• In contrast to "traditional" genetic counseling, which often focuses on reproductive risks, those seeking cancer risk counseling are usually at an increased risk of developing cancer themselves.

• Therefore, much of the discussion and focus of cancer risk counseling concerns the individual's personal risk of developing a disease.

Cancer Risk Counseling• Thus, those who provide cancer risk counseling

should: emphasize prevention of cancer, convey recommendations for surveillance, discuss life-style modifications that may

reduce the risk of developing cancer, and provide an assessment of risk to the

individual and other family members. Gene testing – implications of a positive,

negative or uninformative test result


• The two major decision points in the assessment of cancer risk are:

Is the risk of cancer higher or lower than in the general population?

Is the risk higher or lower than that perceived by the patient?


• The family history questionnaire provides the initial information to answer the first question—individuals with negative family histories and minimal family concerns should be counseled as such, putting their concerns in the context of the general population risk. Cancer screening and prevention information are probably all that is needed.

Assessing the Risks of Hereditary Cancer Syndromes

• Although the specific genes involved in several hereditary cancer syndromes have been discovered, the initial identification of families with these syndromes is based on clinical and family history criteria.

• Hereditary cancer syndromes follow Mendelian inheritance patterns...usually autosomal dominant with reduced penetrance and variable expressivity.

PENETRANCE AND EXPRESSIVITY

• The parent transmitting the gene did not show the trait, even though he or she carried the allele; this is known as incomplete penetrance, that is, the inconsistent phenotypic expression of a gene even though the gene is present.

• The parent of the affected individual expressed the gene but in ways that were not readily recognized; this is known as variable expressivity.

MATERIALS

Hereditary breast and ovarian cancer study

Total number of cases studied – 80

Hereditary Breast Cancer Families - 26

Hereditary Breast and Ovarian Cancer Families - 15

Hereditary Ovarian Cancer Families - 3

Breast and Ovarian Cancer cases - 3

Early onset Breast Cancer cases - 29

Early onset Ovarian Cancer cases - 3

Hereditary Prostate and Breast Cancer families -1

CRITERIA FOR GENETIC TESTING

HBOC STUDY

Early onset of breast cancer ( at or less than 35 years of age).

Two cases of breast cancer diagnosed under the age of 50 years.

Three cases of breast cancer diagnosed under 60 years of age.

Four or more cases of breast cancer diagnosed at any age.

Presence of breast and ovarian cancer in the family or in the same individual.

Male breast cancer with a relative (of either sex) with breast cancer.

CRITERIA FOR GENETIC TESTING

DHPLC

Reverse phase ion exchange chromatography

DHPLC analysis – All fragments analyzed at a basal temperature of 50°C plus two or more higher partial denaturing temperatures.

The DHPLC system’s performance was validated with pUC18 HaeIII digest once every 200 runs.

DHPLC

dHPLC Unit

pUC18 HaeIII digest

80

43

4

10

2 17

4

29

8

26

72

57

45

8

58

7

METHODS - SEQUENCING

Cycle sequencing was done with both forward and reverse primers in separate reaction and run in ABI 310 Genetic Analyzer.

The sequences were analyzed in Sequence Analysis v 3.4.1.

For the samples that showed mutation, DNA from fresh aliquot of lymphocytes was used to sequence again to confirm the results.

RESULTS

HEREDITARY BREAST AND OVARIAN CANCER STUDY

•No: of women with breast/ovarian cancer studied - 80

•No: of controls studied - 1

•No: of disease causing mutation detected - 12/80 (15%)

•No: of variants of unknown significance detected - 1/80 (1.2%)

•No: of samples wherein polymorphisms detected - 77/80 (96%)

•No: of samples with no polymorphisms in BRCA1 - 20/80 (25%)

•No: of samples with no polymorphisms in BRCA2 - 10/80 (12.5%)

CASE -1

50C

60C

B1 E12 - c.4158_4162delCTCTC; p.Ser1369Ser fsX2

50

2 3362

28

6

50

Breast44

3

Breast

Breast50

Breast

Frame shift mutation

Novel mutation

CASE-II

Throat

4541

Uterus

43 36

35

39 41

Breast

Breast

2

Throat

B2 E11O - c.6214_6218delCTTAA; p.Ser2072Ser fsX4

54C

50C


CASE-III

50C

59C

64

Breast

2

48

Breast40

43

Breast41

35

Breast

513

40

Breast40

B1E13 - c.4327C>T; p.R1443X

Nonsense mutation

CASE-IV

B1 E11C - c.1148_1149delAT; p.Asn383Arg fsX6

50C

57C

2

39Breast

38Breast

50

60 50Breast

49

2


Novel mutation

CASE-V

53°C

50°C

B2 E11D - c.5130_5133delTGTA; p.Tyr1693X

30

50

27Breast

2

3 2


CASE-VI

56°C

50°C

B1 E14 -c.4399C>T; p.Gln1467X

75Ovary74

53Liver

60Throat

45Breast

39Breast

Uterine45

53 38

Breast 47

Breast 39

2

2

2

2

2

44

Nonsense mutation

Novel mutation

CASE-VII

50°C

56°C

61

Ovary72

2

282

43Ovary39

B1 E17 - c.5024_5025insT; p. Thr1675Thr fsX4


Novel mutation

CASE-VIII

50°C

59°C

B1EX16- c.4705_4706insTGGAATC; p.Ilefsx5

57Ovary

56

Breast45

2

NOS48

3

3


Novel mutation

CASE-IX, X, XI, XII

33

Breast

2

60NOS

58

2

59Ovary

48Ovary

44

4

439

Breast 33

5058

Breast33

3

2

22

2

NOS

60Ovary

3 222

42Breast

39

CASE-IX, X, XI, XII

50°C

55°C B1 EX2- c.68_69delAG p. Glu23Val fsX16

CASE-IX, X, XI, XII


CASE-XIII- UNKNOWN SIGNIFICANCE

B1 E11G – c.1511G>A; p. R504HBreast30

76Breast

46

4

2

4

50C

57C

Missense mutation

Novel mutation

RESULTS ON MUTATION ANALYSIS

BRCA1 and BRCA2 analysis was done for 80 cases

Number of HBOC cases that showed pathogenic mutation

8/45 (17.8%)

Number of HOC cases that showed pathogenic mutation

1/3 (33.3%)

Number of early onset breast cancers that showed pathogenic mutation

3/29 (10.3%)

Number of early onset ovarian cancers that showed pathogenic mutation

0/3 (0%)

Common Polymorphisms Detected in BRCA1in the exonic region

Polymorphisms Percentage

11K - c.3311T>C; p.L771L 42/80 (52.5%)

11N - c.2612C>T; p.P871L 38/80 (47.5%)

11S - c.3113A>G; p.E1038G 20/80 (25%)

11TU - c.3548A>G; p.K1183R 12/80 (15%)

16 - c.4954A>G; p.M1652I 4/80 (5%)

16 - c.4839G>A; p.S1613G 4/80 (5%)

Common Polymorphisms Detected in BRCA2

in the exonic region


10B - c.1114C>A; p.H372N 35/80 (43.8%)

11B - c.4258G>T; p.D1420Y 2/80 (2.5%)

11C - c.4779A>C; p.E1593D 1/80 (1.25%)

11F - c.2538A>C; p.S846S 2/80 (2.5%)

11H - c.2892A>T; p.K964N 1/80 (1.25%)

11I - c.2971A>G; p.N991D 5/80 (6.25%)

11K - c.3807T>C; p.V1269V 4/80 (5%)

Common Polymorphisms Detected in BRCA1in the intronic region


c.301-41T>C 5/80 (6.25%)

c.441-34T>C 1/80 (1.25%)

c.548-58del T 22/80 (27.5%)

c.4184-10G>A 1/80 (1.25%)

c.4987-68A>G 22/80 (27.5%)

c.4987-92A>G 22/80 (27.5%)

c.5075+66G>A 5/80 (8.1%)

Common Polymorphisms Detected in BRCA2 in the intronic region


c.1-26G>A 4/80 (5%)

c.6841+79delTTAA 32/80 (40%)

c.7807-14T>C 40/80 (50%)

c.8755-66T>C 39/80 (48.8%)

QUESTIONS TO BE DISCUSSED

• What is cancer genetic counseling?• Issues related to setting up a Hereditary

cancer programme in a developing country?

• Socio-economic issues in India and in the West.

• Financial implications in testing.• Guidelines in gene testing• What could be the take home message.