Last updated date: 29-Jan-2023
Originally Written in English
Genes are the fundamental components of heredity. They are normally passed down from generation to generation. They contain DNA, which includes the instructions for proteins manufacture. These proteins perform the majority of the work within cells. For instance, they transport molecules, make structures, break down toxins, and perform a variety of other maintenance tasks.
A mutation refers to a change in the gene or genes that can occasionally occur. This mutation alters the instructions of the gene for producing a protein, causing the protein to malfunction or go missing completely. This could lead to medical conditions known as genetic diseases.
A child can inherit the gene mutation from either one or both parents. Such a mutation can occur during a person’s lifetime as well.
Types of Genetic Diseases
There are numerous types of genetic diseases. However, these genetic diseases list is divided into four categories which include;
Single gene diseases:
When a single gene is known to trigger disease, the condition is a single gene disease. Examples of single-gene disorders are sickle cell disease, cystic fibrosis, Fragile X syndrome, muscular dystrophy, or Huntington disease.
Single-gene diseases have a variety of genetic inheritance patterns, including:
- Autosomal dominant inheritance; only a single copy of the defective gene (from either partner) is required to cause this condition.
- Autosomal recessive inheritance: Two copies of the defective gene (one from every parent) are required to cause this condition.
- X-linked inheritance: This occur when the defective gene is found on the female or an X-chromosome. The X-linked gene can be dominant or recessive.
Work-related diseases, such as hypertension, diabetes, coronary heart disease, low back syndrome, chronic non-specific respiratory disease, cancer, upper limb disorders, and so on, are examples of multifactorial diseases. They are thought to occur due to complex reactions of the genetic factors (polygenic basis) with certain environmental aspects.
The term multifactorial refers to a number of varying influences that work together to trigger the disease to appear. These involve the impacts because of the combination of the genetic factors. However, none of these would likely lead to the disease on their own, and environmental aspects, which would also not cause the disease.
It is thought that a specific combination of environmental and genetic factors works to cause the occurrence of multifactorial diseases. Varying environmental factors can trigger the development of different multifactorial disorders.
Different environmental factors will have an impact on the development of various multifactorial diseases.
Chromosomes abnormalities can be either numerical or structural. The numerical anomaly indicates that a person is missing one of a pair of chromosomes or has more than two chromosomes rather than a pair. A structural abnormality suggests that the structure of the chromosome has been modified in one of several ways. Examples of chromosomal disorders include Down syndrome, Turner syndrome, etc.
Mitochondrial genetic diseases:
Mutations in mitochondrial non-nuclear DNA cause this type of genetic disease. Mitochondria are the minute round or rod-like organelles present in the cytoplasm of both plant and animal cells. They are associated with cellular respiration. 5 to 10 circular DNA pieces may be found in every mitochondrion. Because egg cells retain their mitochondria in fertilization while sperm cells do not, mitochondrial DNA is normally passed from the female parent.
Some examples of mitochondrial diseases include mitochondrial encephalopathy, Leber's hereditary optic atrophy, myoclonic epilepsy, etc.
Signs of Genetic Diseases
Several features may indicate genetic disorders in children and adults. On the other hand, some features are common in people who do not have a genetic disorder. But regardless, you should consult a doctor if you notice at least two of the following indicators;
- A lot of body hair
- Abnormal body odor
- Abnormalities in the ears
- Unusual birthmarks
- Crooked teeth
- Excess skin
- Eyes of different colors
- Eyes with an unusual shape
- Hair that is brittle or sparse
- Increased or decreased sweating
- A large or small tongue
- Stiff or loose joints
- Teeth that are missing or extra
- Unusual facial characteristics or distinct from those of other close family members
- Unusually tall or short height
- Webbed fingers or toes
- White hair patches
Diagnosis of Genetic Diseases
Genetic testing can be done on expectant mothers, newborns, and children of all ages to diagnose genetic diseases. A physical examination can be used to make a diagnosis in other cases.
Most genetic diseases are diagnosed using a certain test. This may involve chromosomes or DNA (the small proteins making up the genes) examination or blood testing for abnormal enzymes. The study of enzymes is referred to as biochemical, genetic testing.
A genetic counselor or a geneticist reviews the medical, family, as well as pregnancy history and conducts tests during the first appointment. Examples of these tests are MRI, x-rays, or genetic tests (including urine or blood tests). Children can be referred to a hospital-based specialty facility.
Some of the types of tests for genetic diseases include;
Predictive genetic testing: This can tell you whether a healthy person, either with or without a family history of a particular disease, is likely to get that disease. Examples are genetic diseases of the heart and cancer.
Presymptomatic genetic testing: This can determine whether a person has a family history of a certain genetic disorder but doesn’t show any symptoms. It also tells if they have genetic changes linked with the disease.
Carrier testing: This can reveal whether or not a person has a single copy of a DNA or gene associated with a particular disease. The term "autosomal recessive" refers to a disease that manifests itself only when two copies of the impaired gene are hereditary. Partners who have a similar autosomal recessive gene have 1 out of 4, or 25%, the possibility of having a child with that disorder in every pregnancy.
Prenatal diagnosis: This is the process of identifying a genetic disease or problem in a growing fetus. Ultrasound (sonograms), screening blood, amniocentesis, chorionic villus sampling (CVS), or percutaneous umbilical blood sampling are some prenatal tests.
Preimplantation studies: This is designed only for in vitro fertilization to diagnose a genetic disorder in the embryo prior to implantation into the uterus.
Newborn screening: This is used to detect genetic disorders that are easily diagnosed and treated at a young age.
Genetic Diseases Treatment
The treatment of genetic diseases varies according to the type of the disease. Doctors can recommend medication, behavioral adjustments, and educational interventions to address symptoms in certain circumstances, such as autism. Other conditions, including phenylketonuria, are manageable with diet. On the other hand, a surgical procedure can be used to correct certain physical symptoms of some genetic diseases.
Children will require ancillary services such as speech therapy, occupational therapy, and other helpful therapies in most situations.
Regardless of the diagnosis, a genetic team or staff will explain the treatment choices with you as well as your family. If necessary, they can make suitable referrals depending on the severity of the condition.
Genetic Diseases Counseling
Genetic counseling aims at telling you if you are at a higher risk of having a genetic disease or having a baby with one. Also, genetic counseling could assist you in making sense of the information and contextualizing it for your baby. It might be done by a geneticist, a physician with special skills, or a genetic counselor. He or she will explain the reason for a disorder, testing options, prognosis, treatment, and medical management.
The sessions of genetic counseling are typically an hour or longer in duration, based on the complexity of the case. There are numerous reasons you need to consider genetic counseling, some of which are as follows:
Being a parent who has an autosomal dominant disorder or a disorder that has been seen in multiple generations
Having pregnancy-related factors (mothers over the age of 35 years)
Having a family history or a child who has the following conditions;
- Abnormalities of the chromosomes (like Down syndrome)
- Cleft lip and palate
- Defects in the neural tube
- Disabilities in learning
- Heart defects
- Impairments in hearing or vision
- Multiple miscarriages (stillbirths or infant deaths)
- Psychiatric problems
- Retardation of the mind
- Short height
- Single-gene flaws (like cystic fibrosis)
Being a mother with one or more of the following conditions;
- Thyroid disease
- Exposure of the fetus or parents to some medications, radiation, chemicals, or infections
- At the period of conception, the father was of advanced age.
- Cases of infertility in which either parent is suspected of having a chromosomal abnormality
- Couples who require assisted reproductive techniques to become pregnant, or people who donate eggs or sperm for such purposes
- Certain ethnic groups or geographic regions have a higher prevalence of certain diseases, including sickle cell disease, Tay-Sachs disease, and thalassemia.
Genetic diseases can occur due to genetic abnormalities like gene mutation or the presence of extra chromosomes. Initially, the consequences of a person's DNA abnormalities were completely unpredictable. However, modern medication has developed techniques for determining the possible health results of genetic disorders.
The medical professionals identified some of the modern best possible practices. They aim at detecting, treating, and potentially preventing certain genetic disorders by using evidence-based statistical observations.