Rare & Genetic Facts

Rare Facts

Rare diseases are long-standing, life threatening, progressively disabling conditions that affect a small percentage of population and require multi-disciplinary care. One rare disease may affect only a handful of patients in one demographic (eg. In the EU) and another might affect as many as 50,000 in other region (eg. Asia). In the EU and United States, as many as 30 million people alone may be affected by one of the 6000 to 8000 rare diseases existing. 

Relatively common symptoms can hide underlying rare diseases leading to misdiagnosis and delaying treatment. Quintessentially disabling, the patient’s quality of life is affected by the lack or loss of autonomy due to the chronic, progressive, degenerative, and frequently life-threatening aspects of the disease.

Although rare and genetic diseases, and many times the symptoms, are uncommon to most doctors, rare diseases as a whole represent a large medical challenge. Combine this with the lack of financial or market incentives to treat  or cure rare diseases, and you have a serious public health problem.

Here are a few statistics and facts to illustrate the breadth of the rare disease problem worldwide.

  1. There are approximately 7,000 different types of rare diseases and disorders, with more being discovered each day
  2. The 7000 to 8000 rare diseases are characterised by a broad diversity of disorders and symptoms that vary not only from disease to disease but also from patient to patient suffering from the same disease
  3. 80% of rare diseases have identified genetic origins whilst others are the result of infections (bacterial or viral), allergies and environmental causes, or are degenerative and proliferative
  4. 30% of children will die before reaching their fifth birthday unless early intervention is given
  5. Rare diseases are responsible for 35% of deaths in the first year of life
  6. If all of the people with rare diseases lived in one country,  we will have 350 millions people and it would be the world’s 3rd most populous country
  7. The fact that there are often no existing effective cures adds to the high level of pain and suffering endured by patients and their families
  8. Approximately 50% of rare diseases do not have a disease specific foundation supporting or researching their rare disease

To help you understand more on rare diseases, here are some Q&A about RARE DISEASES

What is a rare disease?

Briefly speaking, rare diseases suggest diseases with low prevalence. Well known rare diseases include Phenylketonuria, Thalassemia, Osteogenesis Imperfecta, Mucopolysaccharidoses, Spinal Muscular Atrophy and so on. The number of patients may vary from one disease to another, which means some diseases may have bigger population over the others. Moreover, there have been only several cases of certain rare diseases in the world and those are hardly understood.

How do rare diseases occur?

Most rare diseases are result of genetic defects, and are often described as congenital diseases, meaning they are present at birth. However, some rare diseases have infantile and late onset and therefore, we do not think they should be classified as congenital condition. Genetic defects are sometimes caused by sporadic mutation or by inheritance. However, causes of certain rare diseases still remain unknown.

Who may get a rare disease?

There are about 35,000 genes in every human body and each one of us carries around 5 to 10 defective genes. If both parents carry the same defected gene, they may possibly give birth to a baby with a rare disease. Positive family disease history or random gene mutation in the germ cells may both increase the risk of giving birth to a newborn with rare disease.

Are rare disease preventable?

Through certain checkups, it is possible to reduce the newborn’s risks in getting rare diseases. Recommendation procedures are as follows:

1. Attend premarital and prenatal checkups.

2. Apply genetic diagnostic testing before 6 months of pregnancy if the antenatal examination result is abnormal or one of the parent have family history of genetic diseases.

3. Newborn screening after the birth.

What’s newborn screening?

Newborn screening is a comprehensive screening to identify inborn error metabolic diseases that are treatable and with higher probability. Individually these disorders are very rare but as a whole they affect about 1 in 3000 births in Singapore. However, by testing your newborn early such disorders, if identified can be treated early, often before any symptoms occur.

Newborn screening is recognised internationally as an essential preventative health scheme for the early detection of these disorders that can affect the long term health of the baby. Newborns typically appear well at birth, but if left unrecognized these disorders may lead to poor growth, severe illness, brain damage and in some cases death. Talk to your doctor to find our more about newborn screening.

Are rare diseases treatable?

Rare diseases are not always incurable. In most cases, if diagnosed correctly and treated at early stage, patients may prevent serious consequences such as mental and growth retardation. Due to the high cost of developing medical treatment and nutritional products and the small market with so few patients, pharmaceutical industry are not willing to develop, produce or import those products. Therefore, those medical treatment and special formula are called “Orphan Drugs”.

Genetic Facts

As 80% of rare diseases are genetic in origin, and thus are present throughout a person’s life, even if symptoms do not immediately appear. So what exactly is genetic?gene

Genetic is the branch of biology that studies the passing on of traits and features from parents to children. These traits are called “genetic” because they’re determined by tiny structures within human cells called genes. People’s genetic makeup is inherited from their parents and encoded   into the genes in all their cells. It controls many different things, from gender, height, and eye colour to blood type and development of certain diseases.

While many common diseases (such as heart disease, high blood pressure, types of cancer) have some genetic (that is, inherited) components, genetic diseases are those caused by specific, identifiable elements of a person’s genetic makeup.

Genetic diseases can present at any age, infancy, childhood or adulthood. It can cause common problems, for example, developmental delay and poor growth. It can also have rarer presentations such as heart or liver failure.

Many advances have been made in looking for a cure for genetic disease including gene therapy and bone marrow transplantation. However, for most cases, there is no cure. Even so, many patients with genetic diseases can lead fulfilling lives with proper management of their symptoms.

How are GENES passed on through the family?

You get half of your genes from your mother and half from your father. Since your genes determine a lot of what you look like, you look like both of your parents, but you are a completely unique mix. You also pass on half of your genes to your children. But there is no way to choose which genes you can pass on. Genes can be passed down through a family in different inheritance patterns. Examples are autosomal dominant, autosomal recessive, or X-linked. Many genetic syndromes that are caused by gene mutations follow one of these inheritance patterns.

Autosomal recessive genetic diseases Autosomal-recessive-diseases

When both parents carry the same recessive gene, there is a 25% chance that the child will inherit the trait from both parents and have the disease, a 50% chance that the pregnancy will inherit the trait from only one parent, or a 25% chance that the pregnancy will not inherit the trait from either parent. An example of autosomal recessive disease is Pompe disease that occurs 1 in 40,000 live births.

Dominant genetic diseases

They are caused by a mutation in one copy of a gene. If a parent has a dominant genetic disease, then each child has a 50% chance of inheriting the disease. An example of a dominant genetic disease is Achondroplasia that occurs in 1 in 25,000 live births.

Sex-linked genetic diseasesXLinked_D_F

They affect males and females differently. This is a smaller set of diseases related to gene mutations on the X or Y chromosomes. One rare disease linked to X chromosome is Fabry disease.

Chromosome abnormalities

They can occur in any pregnancy. Sometimes these risks are related to the parent’s age and involve extra or missing chromosomes. A second type of chromosome abnormality is a change in the structure or organisation of the chromosomes.

Multi-factorial traits

These occur due to many complex interactions and combinations of maternal, environmental and genetic influences. In most cases predictive genetic testing is not available for multi-factoral traits, however a family history assessment may provide more accurate recurrence risks.

Useful Links

Disclaimer: While we encourage you to surf the Internet for information to broaden your perspective on your child’s illness, please note that not all the medical information provided may be accurate or relevant in the local context. Such general information does not replace the close medical supervision and specific medical advice that your child’s attending doctor will have to offer.

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