Neurogenetics

Neurogenetics - What it is

Genetic disorders are a group of different diseases that can be passed down from one generation to the next. Genes are the “building blocks” which make up the code that determines who we are as a person. Each gene is responsible for coding a protein, and each protein has a specific function in the body. When these genes have a mutation, it can result in a protein that is functional, less functional, or absent. If the protein is absent or less functional, you may have symptoms that result in your being diagnosed with a disease. Many neurological disorders have a genetic basis, and as such, if a genetic disorder is suspected as the cause of your disease, you may be referred for genetic testing.

Genetic tests determine if a patient’s condition was likely caused by a mutated gene, the likelihood of passing the gene on to their children and if healthy family members also carry the gene and are at risk of developing the disease.

There are a broad range of neurological conditions that are hereditary. These can range from nerve disorders (e.g. Charcot Marie Tooth), to muscle disorders (e.g. Muscular Dystrophies), to disorders that affect the brain and spinal cord (e.g. Spinocerebellar Ataxia). Many disorders involving mitochondria (our energy units), and our breakdown of food products (metabolic disorders) can also have neurological manifestations.

Clinicians usually recommend that the extended family gets tested for the gene if more than one family member has been diagnosed with the same condition, because this is a sign of a genetic cause. This would include siblings and children of siblings, whether they are already showing symptoms or not. However, each patient and family member must decide whether or not to proceed with testing, based on their own circumstances and priorities. In this day and age, knowing the results of genetic testing may affect their family planning decisions and help them understand the disease including how it will likely progress.

Genetic testing has implications on the individual, family members, and family planning. Your genetic counsellor can facilitate family discussions on the next steps to ensure family goals are met, and to protect the wishes of all parties. This includes recommendations on who else in the family should get tested, non-disclosure of results if requested, and family planning options - such as preimplantation genetic diagnosis (PGD) to prevent the disease-causing gene from being passed down to the next generation.

With the advancement in technology, new treatments and options for reproduction are available. Knowing if you have the condition and if it can be passed to your children allows you to take necessary actions and make plans that are best for you and your family. Even if no treatments are available, finding out the genetic cause helps advance science and develop new drugs to target diseases.

There can be considerable social and psychological effects of genetic testing – particularly if there are no treatments available for the condition. Different people react differently to their genetic results. It is possible that you may experience guilt about having the disorder, or passing the disorder down to your children. There also may be a sense of frustration or helplessness that comes with knowing that you have an incurable condition. However, you may also feel that you have a better sense of control by being in the know of your genetic status and a sense of relief if the results come back negative. There can also be implications to insurance coverage for yourself or for your extended family members.

Neurogenetics - How to prevent?

At present there are options of preimplantation genetic diagnosis (PGD) and prenatal genetic testing (PGT) that are offered at our partner institutions such as KK Women’s and Children’s Hospital for certain disorders that may be passed down to offspring. Speak to your neurologist or your genetic counsellor for more information.

Neurogenetics - Diagnosis

Genetic testing can involve testing one single gene, a panel of genes, or a more comprehensive whole exome/genome testing. Costs of these test vary significantly.

When you are suspected of having a genetic disorder, you will be referred to a Genetics Clinic for genetic counselling. This would involve a discussion of the disorder that you are suspected of having, the possible long term effects of the disease, possible causes, and recommended genetic test. You will be given time to think about whether you wish to proceed with testing or not. If you are certain about proceeding with testing, it can be arranged on the same visit, but if not, another clinic visit will be scheduled for you to decide about testing. Genetic testing commonly will involve a blood test that will be sent to a local or overseas lab for processing. A separate visit will be arranged to discuss the results of your genetic test.

Before undergoing any clinical or genetic tests, it is recommended to be sufficiently insured. The Ministry of Health (MOH) is working closely with healthcare professionals to come up with guidelines aimed at protecting the rights of individuals with genetic conditions. On 27 October 2021, MOH implemented new rules that prohibit insurers from asking for the results of predictive genetic tests except in very limited circumstances. This protects individuals from being excluded from insurance coverage for conditions detected during genetic testing.

Neurogenetics - Treatments

Genetic counsellors work in a multi-disciplinary team alongside doctors and nurses, to help diagnose and manage genetic conditions. They also work with patients and families to help them understand how genetic information can impact their lives. This includes educating them about their family health history, types of inheritance, disease management and genetic testing. Genetic counsellors also provide psychosocial support and counselling to guide patients and families into making informed decisions and adapting to their genetic risk or conditions.