What is a Rare Genetic Disorder?

A rare genetic disorder is caused by a mutation, or change, in a gene or chromosome. Genetic disorders can therefore be monogenic (single-gene), chromosomal (affecting the chromosome), or complex (multi-factored).

Everyone is born with gene mutations. Your eye color, for example, is determined by the mutation of the gene OCA2. Mutations in this gene affect the amount and type of pigment in the iris, determining your eye color. An OCA2 mutation is expected, common and inherited.

Sometimes genetic mutations are not expected, not common, and oftentimes are not inherited. These make up rare genetic disorders. Individual disorders can have as few as 1 person affected, and as many as 200,000 people affected. Disorders can affect various functions of the body and brain, disabling mobility and intellectual ability.

What are the signs and symptoms?

Signs and symptoms vary widely given mutations can occur in any gene and can affect any part of the body. A single gene mutation can affect the brain, eyes, heart, lungs, liver, skin and/or other organs. Common symptoms include developmental delays, intellectual disability, neurological issues, growth problems, feeding problems, sleep problems, epilepsy, and abnormalities in the structure and/or function of organs.

More specifically, signs and symptoms can include:

  • Developmental delays: inability to sit up, crawl, and/or walk
  • Neurological/intellectual issues: inability to talk, focus or communicate
  • Growth problems: small head size (microcephaly), small limbs or lack of growth
  • Sleep problems: difficulty falling asleep and staying asleep
  • Epilepsy: disorders can include various forms of epilepsy

Many disorders show signs and symptoms at birth, whereas other disorders are neurodegenerative, showing signs in the first years or later in life.

How are rare disorders diagnosed?

Unfortunately, most disorders are misdiagnosed or ignored until the child is old enough to show clear signs. If you suspect your child may have a rare genetic disorder, please speak to your doctor about genetic testing. Insurance generally covers genetic testing for those experiencing symptoms. Ambitcare and ProbablyGenetic are two companies offering free genetic testing in the event insurance is not an option.

How many rare disorders are there?

There are 7,000 individual rare disorders representing over 11,000 disorders as characterized by gene mutations. Rare disorders affect over 200 million children and another 200 million adults.

What are some examples?

Examples of monogenic, or single-gene, disorders include FOXG1 Syndrome, Angelman Syndrome, Rett Syndrome, and Tay-Sachs. More well-known monogenic disorders include Huntington's, Cystic Fibrosis and Muscular Dystrophy.

Examples of chromosomal disorders include Prader-Willi, Patau's, Edward's, Klinefelter, Triple-X, Cri du Chat, and the more well known Down Syndrome.

Complex, or multi-factorial disorders, occur from a combination of mutations plus environmental factors such as diet, chemical exposure, medications, alcohol or tobacco. Examples  include much more well known disorders such as Autism, Alzheimers, Cancer, Diabetes, Spina Bifita, and even Migraines and Arthritis.

Are there treatments or cures?

95% of rare disorders do not have a treatment or cure. Charities like The Children’s Rare Disorders Fund are actively working to change these numbers by sponsoring research to find and develop cures. Institutions, such as universities, around the world conduct this research for many different disorders.

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The Children's Rare Disorders Fund is dedicated to finding a cure for FOXG1 Syndrome, and replicating successes across as many rare genetic disorders as possible through funding gene, stem cell and/or drug therapy research. Children with rare disorders are often neurologically and physically disabled. They are often unable to walk, talk, feed themselves, nor do much of what we take for granted every day. Founded by parents of a toddler affected by FOXG1 Syndrome, The CRD Fund is one of the few charities in the world in which 100% of every donation is directed to the cause - in this case, to the development of cures and treatments.