Legal and ethical issues

There are many highly publicised controversies in genetics,
including the use of modern genetic technologies in genetic
testing, embryo research, gene therapy and the potential
application of cloning techniques. In everyday clinical practice,
however, the legal and ethical issues faced by professionals
working in clinical genetics are generally similar to those in
other specialities. Certain dilemmas are more specific to
clinical genetics, for example, the issue of whether or not
genetic information belongs to the individual and/or to other
relatives remains controversial. Public perception of genetics is
made more sensitive by past abuses, often carried out in the
name of scientific progress. Whilst professionals have learnt
lessons from history, the public may still have anxieties about
the purpose of genetic services.

Informed consent

Competent adults can give informed consent for a procedure
when they have been given appropriate information by
professionals and have had the chance to think about it. With
regard to genetic tests, the information given needs to include
the reason for the test (diagnostic or predictive), its accuracy
and the implications of the result. It may be difficult to ensure
that consent is truly informed when the patient is a child, or
other vulnerable person, such as an individual with cognitive
impairment. This is of most concern if the proposed genetic
test is being carried out for the benefit of other members of the
family who wish to have a genetic disorder confirmed in order
to have their own risk assessed.

Genetic tests in childhood

In the UK the professional consensus is that a predictive
genetic test should be carried out in childhood only when it is
in the best interests of the child concerned. It is important to
note that both medical and non-medical issues need to be
considered when the child’s best interests are being assessed.
There may be a potential for conflict between the parents’
“need to know” and the child’s right to make his or her own
decisions on reaching adulthood. In most cases, genetic
counselling helps to resolve such situations without predictive
genetic testing being carried out during childhood, since
genetic tests for carrier state in autosomal recessive disorders
only become of consequence at reproductive age, and physical
examination to exclude the presence of clinical signs usually
avoids the need for predictive genetic testing for late-onset
dominant disorders.

Confidentiality

Confidentiality is not an absolute right. It may be breached, for
example, if there is a risk of serious harm to others. In practice,
however, it can be difficult to assess what constitutes serious
harm. There is the potential for conflict between an
individual’s right to privacy and his or her genetic relatives’
right to know information of relevance to themselves.
Occasionally patients are reluctant to disclose a genetic
diagnosis to other family members. In practice the individual’s
sense of responsibility to his or her relatives means that, in
time, important information is shared within most families.
There may also be conflict between an individual’s right to
privacy and the interests of other third parties, for example
employers and insurance companies.

Unsolicited information

Problems may arise where unsolicited information becomes
available. Non-paternity may be revealed either as a result of a
genetic test, or through discussion with another family member.
Where this would change the individual’s genetic risk, the
professional needs to consider whether to divulge this
information and to whom. In other situations a genetic test,
such as chromosomal analysis of an amniocentesis sample for
Down syndrome, may reveal an abnormality other than the one
being tested for. If this possibility is known before testing, it
should be explained to the person being tested.

Chromosomal analysis

The correct chromosome complement in humans was
established in 1956, and the first chromosomal disorders
(Down, Turner, and Klinefelter syndromes) were defined in
1959. Since then, refinements in techniques of preparing and
examining samples have led to the description of hundreds of
disorders that are due to chromosomal abnormalities.

Cell Division

Most human somatic cells are diploid (2n46), contain two
copies of the genome and divide by mitosis. Germline oocytes
and spermatocytes divide by meiosis to produce haploid
gametes (n23). Some human somatic cells, for example giant
megakaryocytes, are polyploid and others, for example muscle
cells, contain multiple diploid nuclei as a result of cell fusion.
During cell division the DNA of the chromosomes becomes
highly condensed and they become visible under the light
microscope as structures containing two chromatids joined
together by a single centromere. This structure is essential for
segregation of the chromosomes during cell division and
chromosomes without centromeres are lost from the cell.