The speciality of medical genetics is concerned with the study
of human biological variation and its relationship to health and
disease. It encompasses mechanisms of inheritance,
cytogenetics, molecular genetics and biochemical genetics as
well as formal, statistical and population genetics. Clinical
genetics is the branch of the specialty involved with the
diagnosis and management of genetic disorders affecting
individuals and their families.
Saturday, April 11, 2009
Genetic disease
Genetic disorders place considerable health and economic
burdens not only on affected individuals and their families but
also on the community. As more environmental diseases are
successfully controlled those that are wholly or partly
genetically determined are becoming more important. Despite
a general fall in the perinatal mortality rate, the incidence of
lethal malformations in newborn infants remains constant.
Between 2 and 5% of all liveborn infants have genetic disorders
or congenital malformations. These disorders have been
estimated to account for one third of admissions to paediatric
wards, and they contribute appreciably to perinatal and
childhood mortality. Many common diseases in adult life also
have a considerable genetic predisposition, including coronary
heart disease, diabetes and cancer.
burdens not only on affected individuals and their families but
also on the community. As more environmental diseases are
successfully controlled those that are wholly or partly
genetically determined are becoming more important. Despite
a general fall in the perinatal mortality rate, the incidence of
lethal malformations in newborn infants remains constant.
Between 2 and 5% of all liveborn infants have genetic disorders
or congenital malformations. These disorders have been
estimated to account for one third of admissions to paediatric
wards, and they contribute appreciably to perinatal and
childhood mortality. Many common diseases in adult life also
have a considerable genetic predisposition, including coronary
heart disease, diabetes and cancer.
genetic origin
Though diseases of wholly genetic origin are individually
rare, they are numerous (several thousand single gene
disorders are described) and are therefore important. Genetic
disorders are incurable and often severe. Some are amenable to
treatment but many are not, so that the emphasis is often
placed on prevention, either of recurrence within an affected
family, or of complications in a person who is already affected.
rare, they are numerous (several thousand single gene
disorders are described) and are therefore important. Genetic
disorders are incurable and often severe. Some are amenable to
treatment but many are not, so that the emphasis is often
placed on prevention, either of recurrence within an affected
family, or of complications in a person who is already affected.
Increasing awareness
Increasing awareness, both within the medical profession and
in the general population, of the genetic contribution to disease
and the potential implications of a positive family history, has led
to an increasing demand for specialist clinical genetic services.
Some aspects of genetics are well established and do not require
referral to a specialist genetics clinic – for example, the provision
of amniocentesis to exclude Down syndrome in pregnancies at
increased risk. Other aspects are less well understood – for
example the application of molecular genetic analysis in clinical
practice, which is an area of rapidly advancing technology
requiring the facilities of a specialised genetics centre.
in the general population, of the genetic contribution to disease
and the potential implications of a positive family history, has led
to an increasing demand for specialist clinical genetic services.
Some aspects of genetics are well established and do not require
referral to a specialist genetics clinic – for example, the provision
of amniocentesis to exclude Down syndrome in pregnancies at
increased risk. Other aspects are less well understood – for
example the application of molecular genetic analysis in clinical
practice, which is an area of rapidly advancing technology
requiring the facilities of a specialised genetics centre.
Organisation of genetic services
In the UK, NHS genetic services are provided in integrated
regional centres based in teaching hospitals, incorporating
clinical and laboratory departments usually in close liaison with
academic departments of human genetics.
regional centres based in teaching hospitals, incorporating
clinical and laboratory departments usually in close liaison with
academic departments of human genetics.
Clinical genetics
Clinical services are provided by consultant clinical geneticists,
specialist registrars and genetic associates (nurses or graduates
with specialist training in genetics and counselling). Most
clinical genetic departments provide a “hub and spoke” service,
undertaking clinics in district hospitals as well as at the regional
centre. Patients referred to the genetic clinic are contacted
initially by the genetic associate and many are visited at home
before attending the clinic. The purpose of the home visit is to
explain the nature of the genetic clinic appointment,
determine the issues of importance to the family and obtain
relevant family history information. The genetic associate is
usually present at the clinic appointment and participates in
the counselling process with the clinical geneticist. At the clinic
appointment genetic investigations may be instituted to
establish or confirm a diagnosis and information is given to the
individual or family about the condition regarding diagnosis,
prognosis, investigation, management and genetic
consequences. Written information is usually provided after the
clinic appointment so that the family have a record of the
various aspects discussed. After the appointment, follow-up
visits at home or in the clinic are arranged as necessary. The
genetic associate plays an important role in liaising with
primary care and other agencies involved with the family.
specialist registrars and genetic associates (nurses or graduates
with specialist training in genetics and counselling). Most
clinical genetic departments provide a “hub and spoke” service,
undertaking clinics in district hospitals as well as at the regional
centre. Patients referred to the genetic clinic are contacted
initially by the genetic associate and many are visited at home
before attending the clinic. The purpose of the home visit is to
explain the nature of the genetic clinic appointment,
determine the issues of importance to the family and obtain
relevant family history information. The genetic associate is
usually present at the clinic appointment and participates in
the counselling process with the clinical geneticist. At the clinic
appointment genetic investigations may be instituted to
establish or confirm a diagnosis and information is given to the
individual or family about the condition regarding diagnosis,
prognosis, investigation, management and genetic
consequences. Written information is usually provided after the
clinic appointment so that the family have a record of the
various aspects discussed. After the appointment, follow-up
visits at home or in the clinic are arranged as necessary. The
genetic associate plays an important role in liaising with
primary care and other agencies involved with the family.
genetic disorde
There are a wide variety of reasons leading to referral to the
genetic clinic. The referral may be for diagnosis in cases where
a genetic disorder is suspected; for counselling when a genetic
condition has been identified; for genetic investigation of
family members when there is a family history of an inherited
disorder; or for information regarding prenatal diagnosis. The
disorders seen include sporadic birth defects and chromosomal
syndromes as well as mendelian, mitochondrial and
multifactorial conditions. Specialist or multidisciplinary clinics
are provided by some genetic centres, such as for
dysmorphology, inherited cancers, neuromuscular disorders,
Huntington disease, Marfan syndrome, ophthalmic disorders or
hereditary deafness.
genetic clinic. The referral may be for diagnosis in cases where
a genetic disorder is suspected; for counselling when a genetic
condition has been identified; for genetic investigation of
family members when there is a family history of an inherited
disorder; or for information regarding prenatal diagnosis. The
disorders seen include sporadic birth defects and chromosomal
syndromes as well as mendelian, mitochondrial and
multifactorial conditions. Specialist or multidisciplinary clinics
are provided by some genetic centres, such as for
dysmorphology, inherited cancers, neuromuscular disorders,
Huntington disease, Marfan syndrome, ophthalmic disorders or
hereditary deafness.
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