Medical Genetics

Genetics involves the examination of genes and their impacts. Medical genetics refers to the application of genetic concepts within the realm of medical practice. This encompasses the exploration of inheritance, identification of disease-related genes, diagnosis and therapy, and genetic counselling. Globally, it is estimated that 10 out of 1000 people are affected by single-gene mutations called monogenic diseases. Though genetic disorders are rare, the affected individuals often face significant health challenges, impacting their quality of life. Medical genetics focuses on early diagnosis and targeted treatments for these individuals, helping to manage and even prevent disease progression.

What is medical genetics?

Medical genetics is the medicine speciality that deals with diagnosing genetic disorders and providing appropriate treatment plans. This field focuses on diagnosing traits in adults, especially those that manifest later in life or were missed or overlooked during childhood, enabling more accurate diagnosis and personalised care.  

The various subfields that fall under medical genetics include clinical genetics, biochemical genetics, cytogenetics, molecular genetics, the genetics of common diseases, and genetic counselling.

Genetic disorders

Genetic disorders are the result of gene mutations or changes in the chromosomal sequence. DNA is the genetic material in the body that holds the information to regulate protein synthesis, which is important to perform various cellular functions. This DNA is inherited from our parents; consequently, it is possible to inherit mutated genes from them. Certain genetic disorders may present symptoms at birth, whereas others may exhibit symptoms at a later stage in life.

Gene mutations can be caused by factors such as exposure to chemicals, radiation, and tobacco smoke.

Types of genetic disorders

There are four types of genetic disorders:

• Single gene inheritance: These are also known as monogenetic disorders and refer to alternations in the DNA sequence of a single gene. Cystic fibrosis, alpha- and beta-thalassemia, and sickle cell anaemia (sickle cell disease) are some of the common examples of inherited gene disorders caused by one copy of a single defective gene.
• Multifactorial inheritance: It is also referred to as complex or polygenic inheritance. They are caused by gene mutations and environmental factors. For example, various genes associated with breast cancer susceptibility have been identified on chromosomes 6,11, 13, 14, 15, 17, and 22.
• Chromosomal abnormalities: Chromosomes are unique sets of DNA and protein found in the nucleus of every cell. As the conveyors of genetic material, any anomalies that may occur in chromosomes are likely to cause diseases. Chromosomal abnormalities typically are a result of the defects arising from cell division. For example, Fragile X syndrome and Down syndrome.
• Mitochondrial inheritance diseases: These are the group of inherited disorders caused by impairment of mitochondria, an energy component of the cell. Organs such as the heart and muscles, which require more energy to perform body functions, often get affected by this impairment and present with different symptoms. Common examples include lactic acidosis and stroke-like episodes.

Which diseases are treated under medical genetics?

Most genetic disease treatments focus on symptom relief and enhance the quality of life of the individuals suffering from it. With the expansion of understanding the structure and functioning of the human genome, symptoms of most genetic conditions are treatable. The treatment options for genetic disorders have been expanding due to the increasing availability of genetic engineering technologies. Here are some of the common diseases treated under medical genetics.

• Cystic fibrosis: It is a monogenic disorder arising from CFTR gene mutations. This gene encodes a protein that plays a vital role in regulating the salt movement in and outside the cells. Mutations in this gene cause the development of thick, sticky mucus that blocks the airways, leading to respiratory and digestive problems.
• Down syndrome: It is a chromosomal disorder characterised by the presence of an extra copy of chromosome 21. This results in developmental delays, intellectual disabilities, and characteristic facial features.  
• Sickle cell disease: A monogenic disorder caused by a mutation in the HBB gene, which is the beta-globin subunit of haemoglobin. This mutation results in the creation of an abnormal haemoglobin protein that causes the red blood cells to become sickle-shaped. These small-sized cells coagulate the blood, which, in turn, causes pain and organ damage.  
• Huntington’s disease: A monogenetic disorder caused by a mutation in the HTT gene that leads to the formation of an abnormal Huntington protein, which gradually damages the brain’s neurons. Symptoms include movement disorder, cognitive decline, and even mental issues.
• Haemophilia: These are the group of inherited conditions that decrease the blood clotting capability, which is a process required to stop the bleeding. The most common reason for such a condition is a mutation of the F8 or F9 genes, which activate the clotting factors VIII and IX, respectively. Thus, it results in extended bleeding and bruising.
• Alpha and beta thalassemia: Thalassemia constitutes a category of hereditary hematologic disorders arising from deficiencies in the production of one or more haemoglobin chains. Alpha and beta thalassemia result from a diminished or no production of alpha and beta globin chains, respectively. Imbalances in the globin chain levels precipitate haemolytic events and hinder erythropoiesis.
• Marfan syndrome: This is a disorder of the connective tissue caused by FBN1 gene mutations. This mutation leads to loss of strength and flexibility of the connective tissue, which can cause impairment of the skeleton, eyes, heart, and blood vessels.

In addition to the above conditions, certain disorders, such as cancers, congenital heart defects, diabetes, autism, and coronary artery disease, fall under the purview of multifactorial disorders caused by a combination of genetic, environmental, and lifestyle factors.  

Symptoms of genetic disorders  

Some of the clinical symptoms of genetic disorders include:

• Developmental delay
• Mental retardation
• Congenital abnormalities
• Unusual physical features, such as movement defects, missing fingers, facial anomalies, and cleft lip or palate
• Growth problems
• Learning difficulties
• Hearing defects
• Visual or retinal issues
• Neural tube defects

When to see a medical genetics expert?

A clinical geneticist is a doctor who treats the conditions caused by genetic problems. Individuals are referred to a genetic specialist if the primary healthcare provider suspects they may be at risk for or affected by a genetic disorder. Patients who meet one of the following criteria will be referred to a genetic specialist.

Family history

• Parents, siblings or relatives having a developmental delay, an inherited disorder, or a defect witnessed at birth
• Early deaths in the family due to known reasons
• Members with adult-onset health issues, such as cardiovascular disease, dementia, or cancer, especially if diagnosed early in adulthood
• Couples interested in testing or learning more about genetic diseases that are more common in their ethnic group

Delayed growth and development

• The fear of thinking that kids with developmental delays are associated with genetic problems  
• Infants diagnosed with genetic disease during newborn screening

Reproductive problems

• Women interested in genetic testing or screening
• Multiple pregnancy losses or infant deaths
• Concerns about risks to pregnancy due to lifestyle, medical history, or environmental exposures
• Couples who are close blood relatives
• Pregnant women with abnormal ultrasound or blood test results

A genetic specialist, such as a clinical geneticist or a genetic counsellor, can confirm a diagnosis through testing and require family history to verify the diagnosis and provide treatment options. They can also collaborate with other specialist surgeons, cardiologists, or ophthalmologists, when needed, to decide upon an appropriate treatment plan.  

Treatment  

All diseases contain a hereditary component. However, the amount to which genes contribute to diseases varies, and there is still much to discover. Advances in understanding the genetic pathways underlying these diseases allow for the development of early diagnostic tests, new therapies, or actions to prevent illness onset or reduce disease severity. The diagnosis of genetic disease requires a comprehensive analysis comprising a physical examination, a detailed medical family history, and clinical and laboratory testing.  

The treatment of genetic disorders aims to enable appropriate medical or surgical management of the disease based on the severity of the condition. Here are some of the treatment modalities:

• Symptom-managing medications: The purpose of the treatment of a genetic condition is to manage and prevent the exaggeration of symptoms and improve the quality of life. For instance, during management of cystic fibrosis, medications like bronchodilators and mucolytics help clear mucus from the lungs, and antibiotics are prescribed to treat infections.
• Nutritional guidance and supplementation: Individuals diagnosed with a genetic disorder should have a proper nutrition supplement in their diet. For example, individuals with phenylketonuria must follow a strict diet that is low in phenylalanine as they lack the enzyme responsible for breaking down phenylalanine into amino acids. In addition, the patients should also receive amino acids supplementation along with a low-protein diet.  

Rehabilitative therapies: These include:

• Physical therapy: Helps improve mobility and strength, especially in conditions like muscular dystrophy
• Occupational therapy: Assists in developing daily living skills and adapting to physical limitations
• Speech therapy: Beneficial for those with speech and swallowing difficulties, such as those with Down syndrome

Blood transfusions: Blood transfusions are required on a regular basis, especially for patients suffering from genetic problems like thalassemia or sickle-cell anaemia. Consistent transfusions are essential for such conditions to help control anaemia, replenish healthy red blood cells, and prevent complications such as organ damage or severe fatigue.  

Corrective surgeries: These are surgical procedures or interventions required to correct physical abnormalities or complications. For instance, children who have holes in their hearts since birth because of genetic problems such as Down syndrome may need to have heart surgery.

Chemotherapy: It is used primarily in genetic disorders that predispose individuals to cancers, such as certain types of leukaemia in patients with Down syndrome.

Radiation therapy: Similar to chemotherapy, radiation therapy is used to treat cancers associated with genetic disorders. It targets and destroys cancer cells.

Organ transplantation: In severe cases, organ transplantation may be necessary. For instance, liver transplants can be lifesaving for individuals with certain metabolic disorders, like Wilson’s disease.

Benefits of early intervention by a medical genetics expert

Early intervention by medical genetics experts is crucial in addressing various health concerns and ensuring optimal outcomes for individuals and their families. The primary benefit of an early intervention is preventing disease onset or reducing its severity. By conducting precise diagnoses, a medical geneticist can inform the prognosis of the condition and decide upon treatment options for improved patient care.

Additionally, early genetic testing, particularly newborn screening, can provide valuable information about potential genetic conditions, especially in families with a history of such disorders. This knowledge can also facilitate the early implementation of surveillance measures and proactive management strategies, enhancing the chances of timely interventions and ensuring better health outcomes.

How team Fortis helps you during your treatment journey?

Team Fortis accompanies you at each step of the journey through managing a genetic disorder by providing comprehensive care from diagnosis to ongoing management. Their genetic expert team offers precise diagnosis through advanced genetic testing and a detailed family history analysis to develop personalised treatment plans. Genetic counsellors help an individual understand their condition and provide guidance on the available treatments.  

Fortis Healthcare is also equipped with allied health professionals, such as nutritionists, psychologists, and therapists, who provide additional support tailored to individual needs.

Conclusion

With the advancement in research in the field of medical genetics, several innovative therapies, such as gene therapy and personalised medicine, have emerged as promising entities that can offer more effective management of genetic disorders.