Medical genetics
Medical genetics is the branch of medicine that involves the diagnosis and management of hereditary disorders. Medical genetics differs from human genetics in that human genetics is a field of scientific research that may or may not apply to medicine, while medical genetics refers to the application of genetics to medical care. For example, research on the causes and inheritance of genetic disorders would be considered within both human genetics and medical genetics, while the diagnosis, management, and counselling people with genetic disorders would be considered part of medical genetics.
In contrast, the study of typically non-medical phenotypes such as the genetics of eye color would be considered part of human genetics, but not necessarily relevant to medical genetics. Genetic medicine is a newer term for medical genetics and incorporates areas such as gene therapy, personalized medicine, and the rapidly emerging new medical specialty, predictive medicine.
File:Autosomal dominant and recessive.svg|thumb|Autosomal dominant and autosomal recessive inheritance, the two most common Mendelian inheritance patterns. An autosome is any chromosome other than a sex chromosome.|500px
Scope
Medical genetics encompasses many different areas, including clinical practice of physicians, genetic counselors, and nutritionists, clinical diagnostic laboratory activities, and research into the causes and inheritance of genetic disorders. Examples of conditions that fall within the scope of medical genetics include birth defects and dysmorphology, intellectual disabilities, autism, mitochondrial disorders, skeletal dysplasia, connective tissue disorders, cancer genetics, and prenatal diagnosis. Medical genetics is increasingly becoming relevant to many common diseases. Overlaps with other medical specialties are beginning to emerge, as recent advances in genetics are revealing etiologies for morphologic, endocrine, cardiovascular, pulmonary, ophthalmologist, renal, psychiatric, and dermatologic conditions. The medical genetics community is increasingly involved with individuals who have undertaken elective genetic and genomic testing.Subspecialties
In some ways, many of the individual fields within medical genetics are hybrids between clinical care and research. This is due in part to recent advances in science and technology that have enabled an unprecedented understanding of genetic disorders.Clinical genetics
Clinical genetics a medical specialty with particular attention to hereditary disorders. Branches of clinical genetics include:Examples of genetic syndromes that are commonly seen in the genetics clinic include chromosomal rearrangements, Fragile X syndrome, Marfan syndrome, neurofibromatosis, Huntington disease, familial adenomatous polyposis, and many more.
Training and qualification
In Europe, the training of physicians in Clinical/Medical Genetics is overseen by . This organization aims to harmonize and raise the standards of medical specialist training across Europe. The UEMS has established to guide the education and training of medical geneticists.Individuals seeking acceptance into clinical genetics training programs must hold an MD, or in some countries, an MB ChB or MB BS degree. These qualifications ensure that trainees have the foundational medical knowledge required to specialize in Medical Genetics. The optimal training program involves a total of five years: one year of general medical training followed by four years of specialized training in Medical Genetics. This specialized training should include at least two years of clinical patient care and at least six months in genetic laboratory diagnostics. Trainees' progress is evaluated through a structured program that begins with observation and progresses to independent practice under supervision, culminating in the ability to manage complex cases independently.
Final certification involves a comprehensive assessment, which may include national examinations or the . This certificate serves as a benchmark for high standards in the specialty across Europe and is increasingly recognized by various national regulatory authorities.
In the United States, physicians who practice clinical genetics are accredited by the American Board of Medical Genetics and Genomics. In order to become a board-certified practitioner of Clinical Genetics, a physician must complete a minimum of 24 months of training in a program accredited by the ABMGG. Individuals seeking acceptance into clinical genetics training programs must hold an M.D. or D.O. degree and have completed a minimum of 12 months of training in an ACGME-accredited residency program in internal medicine, pediatrics, obstetrics and gynecology, or other medical specialty.
In Australia and New Zealand, clinical genetics is a three-year advanced training program for those who already have their primary medical qualification and have successfully completed basic training in either paediatric medicine or adult medicine. Training is overseen by the Royal Australasian College of Physicians with the Australasian Association of Clinical Geneticists contributing to authorship of the curriculum via their parent organization, the Human Genetics Society of Australasia.
Metabolic/biochemical genetics
genetics involves the diagnosis and management of inborn errors of metabolism in which patients have enzymatic deficiencies that perturb biochemical pathways involved in metabolism of carbohydrates, amino acids, and lipids. Examples of metabolic disorders include galactosemia, glycogen storage disease, lysosomal storage disorders, metabolic acidosis, peroxisomal disorders, phenylketonuria, and urea cycle disorders.Cytogenetics
Cytogenetics is the study of chromosomes and chromosome abnormalities. While cytogenetics historically relied on microscopy to analyze chromosomes, new molecular technologies such as array comparative genomic hybridization are now becoming widely used. Examples of chromosome abnormalities include aneuploidy, chromosomal rearrangements, and genomic deletion/duplication disorders.Molecular genetics
Molecular genetics involves the discovery of and laboratory testing for DNA mutations that underlie many single gene disorders. Examples of single gene disorders include achondroplasia, cystic fibrosis, Duchenne muscular dystrophy, hereditary breast cancer, Huntington disease, Marfan syndrome, Noonan syndrome, and Rett syndrome. Molecular tests are also used in the diagnosis of syndromes involving epigenetic abnormalities, such as Angelman syndrome, Beckwith-Wiedemann syndrome, Prader-willi syndrome, and uniparental disomy.Mitochondrial genetics
genetics concerns the diagnosis and management of mitochondrial disorders, which have a molecular basis but often result in biochemical abnormalities due to deficient energy production.There exists some overlap between medical genetic diagnostic laboratories and molecular pathology.
Genetic counseling
Genetic counseling is the process of providing information about genetic conditions, diagnostic testing, and risks in other family members, within the framework of nondirective counseling. Genetic counselors are non-physician members of the medical genetics team who specialize in family risk assessment and counseling of patients regarding genetic disorders. The precise role of the genetic counselor varies somewhat depending on the disorder.When working alongside geneticists, genetic counselors normally specialize in pediatric genetics which focuses on developmental abnormalities present in newborns, infants or children. The major goal of pediatric counseling is attempting to explain the genetic basis behind the child's developmental concerns in a compassionate and articulated manner that allows the potentially distressed or frustrated parents to easily understand the information. As well, genetic counselors normally take a family pedigree, which summarizes the medical history of the patient's family. This then aids the clinical geneticist in the differential diagnosis process and help determine which further steps should be taken to help the patient.
History
Although genetics has its roots back in the 19th century with the work of the Bohemian monk Gregor Mendel and other pioneering scientists, human genetics emerged later. It started to develop, albeit slowly, during the first half of the 20th century. Mendelian inheritance was studied in a number of important disorders such as albinism, brachydactyly, and hemophilia. Mathematical approaches were also devised and applied to human genetics. Population genetics was created.Medical genetics was a late developer, emerging largely after the close of World War II when the eugenics movement had fallen into disrepute. The Nazi misuse of eugenics sounded its death knell. Shorn of eugenics, a scientific approach could be used and was applied to human and medical genetics. Medical genetics saw an increasingly rapid rise in the second half of the 20th century and continues in the 21st century.
Current practice
The clinical setting in which patients are evaluated determines the scope of practice, diagnostic, and therapeutic interventions. For the purposes of general discussion, the typical encounters between patients and genetic practitioners may involve:- Referral to an out-patient genetics clinic or an in-hospital consultation, most often for diagnostic evaluation.
- Specialty genetics clinics focusing on management of inborn errors of metabolism, skeletal dysplasia, or lysosomal storage diseases.
- Referral for counseling in a prenatal genetics clinic to discuss risks to the pregnancy, test results, and/or options for prenatal diagnosis.
- Multidisciplinary specialty clinics that include a clinical geneticist or genetic counselor.
Diagnostic evaluation