Genetic Diagnosis in Adults

Carrier screening

Some adults, either prior to marriage or starting a family, will decide to undergo carrier screening, a specific type of genetic testing. Even though an adult may not show any symptoms of a rare disease, it is possible that they are carriers for a gene or chromosomal change, that can be passed onto their children who may then in turn develop a rare disease. 

Genetic carrier screening tests for rare diseases and gene changes that are inherited in an autosomal recessive inheritance pattern, and in an X-linked recessive pattern.

When syndromes are inherited in an autosomal recessive pattern, it means that both parents of the affected child carry copies of the gene mutation or change. With each pregnancy, affected couples have a 25% chance of passing the both copies of the mutation to their child, thus triggering a rare disease.  Examples of syndromes inherited in this way include Tay-Sachs, Cystic Fibrosis, Fragile X, and Sickle Cell Anemia. With each pregnancy there is a 50% chance of one copy of the gene mutation being passed onto the child, which would make them a carrier as well. 

Carrier screening may also test for gene changes that may cause an autosomal dominant syndrome. However a patient with a gene change that can be inherited in an autosomal dominant pattern, will be themselves affected by the rare disease, and should display symptoms. Usually in this instance, carrier screening is not necessary. 

Rare disease diagnosis in adults

Genetic diagnosis in adults can also involve diagnosis of a rare disease or genetic syndrome. This diagnosis may be triggered due to symptoms of a rare disease, or revealed through carrier screening, depending on the type of genetic syndrome, and the severity of symptoms.

Some syndromes have symptoms that develop later in life, and may not be diagnosed until adulthood. Werner syndrome, for example, presents with premature ageing, but this does not usually present until an individual reaches their thirties. 

Sometimes symptoms of a syndrome are not severe, or not identified as related to a specific rare disease until much later in life. Many syndromes present with symptoms that vary in their presentation and severity, even amongst members of the same family with the same condition. Often this difference in symptoms is related to the extent, or location of the gene and/or chromosomal change responsible for causing the syndrome. 

Adults may experience symptoms of a genetic syndrome for many years, and receive several misdiagnosis along the way, before reaching an accurate diagnosis. 56% of Ehlers Danlos patients, for example, receive at least one Ehlers Danlos misdiagnosis en-route to fully understanding their condition. 

The Process

The genetic diagnosis process should start with genetic counseling. This is an essential first step, before undergoing any type of genetic testing or screening.

Genetic counseling is vital to the diagnosis process for so many reasons: a genetic counselor can provide information on the different types of genetic testing available to adults, they will also take a full medical, family history. Genetic counselors offer emotional and mental support during the diagnostic process, and they are instrumental in coordinating care and testing options among different medical professionals. 

While genetic counseling should be the initial step in the process, it should also accompany an adult rare disease patient through every part of their diagnostic journey. Through the testing and diagnosis stages, and even afterwards in terms of supporting their long term care and treatment needs, if relevant. 

Genetic counselors will also make recommendations for genetic tests an adult should consider undergoing. Depending on the reasons for their starting the genetic diagnosis process, if they have any identifiable symptoms of a rare disease, or a family history- a genetic counselor will help a potential rare disease patient choose the most targeted testing to ensure the most accurate diagnosis. 

The genetic diagnosis process does not end with a confirmed diagnosis. Genetic counselors are able to support rare disease patients through a diagnosis and beyond, in order to ensure they relieve the best possible care and long term management of their condition. 

The Future

There is still much that can be done to improve the genetic diagnosis process for adults, in terms of ensuring it is more accurate and more accessible. 

Online genetic counseling is one advancement that works well for adults- allowing them to access genetic counselors and their crucial services virtually. This removes location obstacles, and obstacles related to travelling for appointments. It brings genetic counseling into the homes of those who need it, along with all of the other benefits telehealth brings patients.

Accurate genetic diagnosis for adults is crucial in ensuring adult rare disease patients receive the necessary support needed to manage their symptoms and condition.

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