Six Most Common Hereditary Diseases

10 September 2019 Medoozle Staff
Stylistic close up view of X and Y chromosomes

Our genes determine our physical traits and other internal functionalities of our bodies. While we inherit physical traits from our parents such as hair colour, texture or eye colour, some people inherit medical conditions through defective genes that are passed on in a family and with each generation of children.  

There are three categories of genetic disorders.

  1. Monogenetic disorders. These are caused by a mutation in a single gene. The mutation may occur on one or both chromosomes. Sickle cell disease is an example.
  2. Chromosomal disorders. Here, chromosomes or parts of chromosomes are missing, have changed or have chromosome abnormalities. Chromosomes are the structures that hold our genes. An example of a chromosomal disorder is Down syndrome.
  3. Multifactorial inheritance disorders. These are caused by a combination of small inherited variations in genes, often acting together with environmental factors. Heart disease, diabetes, and most cancers are examples.

Most hereditary diseases are monogenic. Monogenic disorders may be recessive, dominant or X-linked. All human beings have two copies of each gene called “allele”; one copy on each side of the chromosome pair. Recessive diseases occur due to damages in both copies or alleles. Dominant diseases involve damage to only one gene copy. X-linked diseases are linked to defective genes on the X chromosome which is the sex chromosome.  Generally, here are six most common hereditary diseases.

Sickle Cell Anaemia

Sickle-cell anaemia is a blood related disorder that affects the haemoglobin molecule and causes the entire blood cell to change shape under stressed conditions. Unlike healthy red blood cells, which are usually smooth and donut-shaped, sickled red blood cells cannot squeeze through small blood vessels. Instead, they stack up and cause blockages that deprive organs and tissues of oxygen-carrying blood.

Sickle cell anaemia generally has a low prevalence but affects more people whose ancestors come from Sub-Saharan Africa, South America, Central America, Saudi Arabia, India, and Mediterranean countries. It is generally characterized by paleness, painful body and joints and fever. The only known cure at present is a bone marrow transplant.

Sickle cell anaemia is one of the most common hereditary diseases in the UAE. 

Cystic Fibrosis

Cystic Fibrosis is a genetic disorder that affects the respiratory, digestive and reproductive systems involving the production of abnormally thick mucus linings in the lungs and can lead to fatal lung infections. Symptoms include very salty-tasting skin; persistent coughing, at times with phlegm; wheezing or shortness of breath; an excessive appetite but poor weight gain; and greasy, bulky stools. Cystic fibrosis is most common among Caucasians of Northern European descent. However, it’s known to occur in all ethnic groups.

Down syndrome

Down syndrome is a genetic condition that causes delays in physical and intellectual development. Individuals with Down syndrome have 47 chromosomes instead of the usual 46. It is the most frequently occurring chromosomal disorder. Down syndrome can have many effects, and it’s very different for each person. Some will grow up to live almost entirely on their own, while others will need more help taking care of themselves. People with Down syndrome tend to have certain physical features in common. For example, they often have flat noses and small ears. Many people with Down syndrome don’t have any other health issues, but some do. Common conditions include heart problems and trouble hearing and seeing.

Life span for people with Down syndrome has improved dramatically in recent decades as there are more support and better services available. You can join a support group in the UAE, as well as attend down syndrome related events.

Alzheimer’s Disease

Alzheimer's disease is a type of dementia that causes problems with memory, thinking and behaviour. Symptoms usually develop slowly and get worse over time, becoming severe enough to interfere with daily tasks. The most common early symptom of Alzheimer's is difficulty remembering newly learned information. As Alzheimer's advances through the brain it leads to increasingly severe symptoms, including disorientation, mood and behaviour changes; deepening confusion about events, time and place; unfounded suspicions about family, friends and professional caregivers; more serious memory loss and behaviour changes; and difficulty speaking, swallowing and walking. The greatest known risk factor is increasing age, and the majority of people with Alzheimer's are 65 and older. 

Alzheimer’s is still rare in the UAE, mainly because the country has a relatively young population. As this population ages however, the prevalence of the disease is expected to rise.

Huntington’s disease

Huntington’s disease is a degenerative brain disorder, in which afflicted individuals lose their ability to walk, talk, think, and reason. They easily become depressed and lose their short-term memory capacity. Individuals may also experience a lack of concentration and focus.  The disease typically begins between ages 30-45, and every individual with the gene for the disease will eventually develop the disease. It is a rare disease and affects 5-7 people per 100,000. There is no treatment or cure for Huntington’s disease, and the patient eventually becomes completely dependent on others for daily functioning.

Thalassemia

Thalassemia is a blood related genetic disorder which involves the absence of or errors in genes responsible for production of haemoglobin, a protein present in the red blood cells. The low haemoglobin and fewer red blood cells of thalassemia may cause anaemia, leaving you fatigued. Ongoing treatments include regular blood transfusions to boost haemoglobin levels in the blood thus people can live normal lives. 

 

Although genetic disorders cannot be prevented in affected individuals, symptom severity may be decreased by working with your doctor.  Many affected people are able to live near normal lives with the help of therapy and support groups. Discussion of your family's medical history with your doctor can also help you determine if there are diseases which you are at a higher risk of developing. If you or your partner have a known history of genetic disorders in either family, you should discuss this your doctor, who can advise you on the risks of passing on the disorder to your child and how to minimise such risks.

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