The relationship between the 8680C>T BRCA2 mutation and
familial endometrial cancer risk
Name
ID:
Tutorial group
Faculty of Health, Medicine, and Life Sciences (FHML)
Maastricht University
Course BBS1005
Practical date:
Hand-in date:
, 1. Introduction
With the human body having more than one hundred trillion cells, that typically divide every 24
hours on average, mistakes in this process are bound to happen (1). Each day, a mutation occurs in
the DNA of billions of cells. This often has no distinct effect, but, most dangerously, it may lead to a
cell being able to divide at a high rate, creating a growing cluster of mutant clones: a tumor.
Mutations occurring in so-called tumor-suppressor genes can be the cause of this, as the loss in their
proliferation-suppressing function contributes to cancer (2). One of such tumor-suppressor genes is
the BRCA2 gene, which encodes for a nuclear protein which is key in repairing double-stranded DNA
breaks (3). A mutation in this gene elevates the likelihood of the development of breast cancer or
ovarian cancer in females, as well as prostate cancer in males (4). Also, colon, stomach, gallbladder,
and bile duct cancer risks may be increased with BRCA2 mutations (5). Such a mutation can happen
accidentally during DNA replication, but it can also be inherited from a parent through one of their
germ cells.
Mutations in BRCA2 have been shown to influence the occurrence of several cancers (3), but
research on the link to endometrial cancer has shown mixed results. Smith et al. suggested that
BRCA2 mutation carriers showed a link between the loss of function of this tumor-suppressor gene
and endometrial cancer development, but this could be a somatic or sporadic mutation rather than a
germline genetic characteristic (6). On the other hand, Kitson et al. have not found a significantly
increased risk for endometrial cancer in BRCA variant-carrying women (7).
DNA from buccal cells of Romanian women with a familial or sporadic endometrial cancer diagnosis
was screened for a rare BRCA2 germline mutation for this research, conducted by Maastricht
University. After obtaining a saliva sample from each participant, the DNA was isolated via the
process of extraction from the cells and purification. To evaluate the reliability of the use of buccal
cell DNA, obtained using saliva samples, first-year Biomedical Sciences students at Maastricht
University conducted an experiment to test the purity and concentration of DNA extracted from
saliva in the same way as done for the Romanian study population. The purity of the samples’ DNA
was calculated using the A260/A280 ratio, as the DNA absorbance at 260 nm is 1.6-2.0 times more
than the absorbance at 280 nm, so the ratio between these values should be between 1.6 and 2.0 for
optimal DNA purity (8). The concentration of the DNA can be calculated using the formula
(−36 x ( A 280−A 320))+(62.9 x ( A 260− A 320)) (9). Ax here means the absorption value for a
wavelength of x nm (nanometers).
The isolated buccal cell DNA of the Romanian women went through the process of PCR-RFLP:
polymerase chain reaction-restriction fragment length polymorphism (10). This analysis makes use of
2
familial endometrial cancer risk
Name
ID:
Tutorial group
Faculty of Health, Medicine, and Life Sciences (FHML)
Maastricht University
Course BBS1005
Practical date:
Hand-in date:
, 1. Introduction
With the human body having more than one hundred trillion cells, that typically divide every 24
hours on average, mistakes in this process are bound to happen (1). Each day, a mutation occurs in
the DNA of billions of cells. This often has no distinct effect, but, most dangerously, it may lead to a
cell being able to divide at a high rate, creating a growing cluster of mutant clones: a tumor.
Mutations occurring in so-called tumor-suppressor genes can be the cause of this, as the loss in their
proliferation-suppressing function contributes to cancer (2). One of such tumor-suppressor genes is
the BRCA2 gene, which encodes for a nuclear protein which is key in repairing double-stranded DNA
breaks (3). A mutation in this gene elevates the likelihood of the development of breast cancer or
ovarian cancer in females, as well as prostate cancer in males (4). Also, colon, stomach, gallbladder,
and bile duct cancer risks may be increased with BRCA2 mutations (5). Such a mutation can happen
accidentally during DNA replication, but it can also be inherited from a parent through one of their
germ cells.
Mutations in BRCA2 have been shown to influence the occurrence of several cancers (3), but
research on the link to endometrial cancer has shown mixed results. Smith et al. suggested that
BRCA2 mutation carriers showed a link between the loss of function of this tumor-suppressor gene
and endometrial cancer development, but this could be a somatic or sporadic mutation rather than a
germline genetic characteristic (6). On the other hand, Kitson et al. have not found a significantly
increased risk for endometrial cancer in BRCA variant-carrying women (7).
DNA from buccal cells of Romanian women with a familial or sporadic endometrial cancer diagnosis
was screened for a rare BRCA2 germline mutation for this research, conducted by Maastricht
University. After obtaining a saliva sample from each participant, the DNA was isolated via the
process of extraction from the cells and purification. To evaluate the reliability of the use of buccal
cell DNA, obtained using saliva samples, first-year Biomedical Sciences students at Maastricht
University conducted an experiment to test the purity and concentration of DNA extracted from
saliva in the same way as done for the Romanian study population. The purity of the samples’ DNA
was calculated using the A260/A280 ratio, as the DNA absorbance at 260 nm is 1.6-2.0 times more
than the absorbance at 280 nm, so the ratio between these values should be between 1.6 and 2.0 for
optimal DNA purity (8). The concentration of the DNA can be calculated using the formula
(−36 x ( A 280−A 320))+(62.9 x ( A 260− A 320)) (9). Ax here means the absorption value for a
wavelength of x nm (nanometers).
The isolated buccal cell DNA of the Romanian women went through the process of PCR-RFLP:
polymerase chain reaction-restriction fragment length polymorphism (10). This analysis makes use of
2
