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A medical geneticist is a medical specialist who evaluates patients and then diagnoses, counsels and manages patients who are affected by genetic abnormalities/hereditary disorders.
Medical genetics shouldn't be confused with human genetics as the latter involves the field of scientific research that may or may not involve medical genetics.
In order to qualify as a medical geneticists, a doctor has to complete their undergraduate training that consists of a 5-6 year medical and surgical degree to become a medical doctor. A 1-2 year internship training phase then needs to be completed to be allowed to apply for a specialist position.
The residency programme in medical genetics takes 4 yrs to complete, after which the doctor becomes a qualified medical geneticist.
Sub-specialties in medical geneticists are available for a specialist to train in further, and this requires training in a fellowship programme that takes 1-2 years to complete. The fellowships that are available include:
Clinical genetics - this is the practice of clinical medicine that pays particular attention to hereditary disorders. Conditions that are referred to these specialists include birth defects, autism, developmental delay, epilepsy and a short stature. Genetic syndromes that are commonly seen by clinical geneticists include Down syndrome, Turner syndrome, Marfan syndrome, Fragile X syndrome and other chromosomal abnormalities.
Metabolic/biochemical genetics - this discipline involves diagnosing and managing inborn errors of metabolism in patients that have enzymatic deficiencies. These deficiencies then negatively affect biochemical pathways that are involved in the metabolism of dietary sources such as fats, amino acids and carbohydrates. Metabolic disorders managed by these geneticists include glycogen storage disease, galactosaemia, metabolic acidosis and phenylketonuria.
Cytogenetics - here, the focus is on the study of chromosomes and chromosomal abnormalities. Where cytogenetics relied on analyzing chromosomes microscopically, cytogenetics uses new molecular technologies such as array comparative genomic hybridization. Chromosome abnormalities managed by these geneticists include genomic deletion/duplication disorders and other chromosomal rearrangements.
Molecular genetics - this sub-specialty involves the discovery of and laboratory testing for DNA mutations that is the cause of many single gene disorders that include issues such as cystic fibrosis, achondroplasia, Duchenne muscular dystrophy, Huntington disease, hereditary breast cancer involving BRCA1/2, Rett syndrome and Noonan syndrome. Molecular tests are also used to diagnose syndromes involving epigenetic abnormalities such as Prader-willi syndrome, Angelman syndrome and uniparental disomy.
Mitochondrial genetics- this discipline focuses on the diagnosis and management of mitochondrial disorders. These conditions result in biochemical abnormalities due to a deficiency in energy production by the mitochondria in cells.
Diagnostic evaluation in medical genetics
Medical geneticists will take a comprehensive history from the patient and/or their family members (usually being their parents) and perform a physical examination in order to produce a differential diagnosis (list of possible diagnoses).
A medical geneticist will then be aided by the following in order to narrow the differential diagnosis and provide a final diagnosis of the patient:
Using programmes such as SimuConsult to consult with colleagues and peers. Here, the patients relevant clinical information together with a picture of the affected anatomy is made available for review.
Making use of National Library of Medicine Gene Review articles to gather more information on the list of possible diagnoses.
Chromosome studies are used determine a cause for issues such as birth defects and developmental delays. Chromosomal analysis is done by performing procedures such as using a karyotype to identify each chromosome under a microscope, fluorescent in-situ hybridization (FISH) that involves labeling of probes that attach to specific DNA sequences, chromosome painting and array comparative genomic hybridization.