Role of clinical genetics in medicine

Who provides this service•Varies depending on structure and

funding of service but is in reality provided by many different individuals

▫Medical genetic staff▫Physicians and surgeons with a special

interest▫Nurses with a special interest▫Obstetricians▫General practitioners

Clinical Genetic Service

•Cytogenetic laboratory•Molecular genetic laboratory•Clinical genetics

Clinical Genetics

•Diagnosis of genetic disorders•Provide information to individuals and

families about the genetic disease affecting their family

•Clinical surveillance of individuals at risk of genetic disease

•Coordination of screening of at risk individuals

•Laboratory liaison•Education

Clinical genetics

•Mainly an outpatient speciality•Patients seen

▫In clinic▫At home▫On the ward

Diagnosis

•May be known prior to the appointment and inheritance of condition in the family known

•May be made in clinic from history and examination

•May be unknown but pedigree analysis may help in establishing risks

Diagnosis

•Clinical geneticists are specifically trained to recognise genetic disease through

▫Pedigree analysis▫Phenotypic and pattern recognition▫Individual patient research

Appropriate investigation

•Appropriate investigation of complex disorders as a result of phenotypic and pattern recognition of the individual and family

•Use of medical genetic databases•Knowledge on available genetic testing

Diagnosis of genetic disease

•Each genetic disease is rare and genetic practitioners are more likely to recognise a condition because they may have seen it or have read about the condition before

•Physicians and surgeons with a special interest may also have extensive knowledge of a particular group of genetic conditions

The process

•Taking the family tree•Collecting the medical history in detail•Examination of the affected or at risk

individual if appropriate

Surveillance

•Knowledge of disorder allows appropriate clinical surveillance of individuals at risk of genetic disease

•Development of guidelines for the management of individuals at risk

•Coordination of screening of at risk individuals

Providing the information

•Non directive

•Non judgmental

•Fully informative

Clinical counselling•Affective communication with family

about the natural history and prognosis of genetic disease

•Provide risk information for relatives including offspring

•Prenatal/antenatal counselling•Provide support for individuals and

families with genetic disease

Genetic Counselling An educational process that seeks to

assist affected and/or at risk individuals to understand the nature of the genetic disorder, its transmission and the options open to them in management and family planning

Kelly 1986

Genetic counselling

Genetic counselling is the process by which patients or relatives at risk of a disorder that may be hereditary are advised of the consequences of the disorder, the probability of developing or transmitting it and of the ways in which this may be prevented, avoided or ameliorated

Associate/nurse led clinics

•Tend to be disease specific•Provide information about the risks and

natural history, including complications•Work to frequently reviewed guidelines•Provide emotional support for individuals

and families with genetic disorders

Providing support•Support and counsel individuals

considering and during genetic testing▫Diagnostic▫Predictive▫prenatal

•Provide bereavement and post termination counselling

•Ensuring families receive available services and benefits

Clinical Genetics - laboratory

•Clinical support for cytogenetic and molecular genetic laboratories – including the interpretation of results in the clinical context

•Liase with other clinicians using genetic laboratory services

Pharmacogenetic

•Currently clinical genetic departments are rarely involved, however this may change as more sub typing of disease and individuals becomes possible

Pharmacogenetics

Disease susceptibility Focused screening Early Diagnosis

Targeted therapy

PharmacogeneticsClinical diagnosis

Biochemical diagnosis

Genotype diagnosisSomatic or germline

Genotype diagnosisPredicting drug response•Diabetes

▫HLA, HNF1 and 4, PPAR, glucokinase ▫e.g. sulphonylurea very affective in HNF1

•Asthma▫IGE receptor, airway remodelling, epithelial

barrier (protease)•Cancer

▫Imantinib active against tumours with activated KIT mutations (GIST’s), 82% response rate

▫Herceptin for Ca breast with ERBB2 over expression

Clinical Genetics

•Diagnosis of genetic disorders•Provide information to individuals and

families about the genetic disease affecting their family

•Clinical surveillance of individuals at risk of genetic disease

•Coordination of screening of at risk individuals

•Laboratory liaison•Education