What is a genetic test and what can it find.
A genetic test looks at one or more genes in your DNA to see if there are any changes or spelling mistakes which may affect a person’s growth, development and health, depending on the condition in question. DNA is typically taken from a blood sample, although for young children clinicians may be able to do the test on a saliva sample.
For many MACS conditions, a new genetic test called whole genome sequencing (WGS) is routinely offered. WGS was introduced to the NHS in early 2022. WGS looks at a person’s whole DNA instructions or code, however, not all of the code is analysed. Only genes which are associated with the MACS condition or symptoms in question will be looked at. Therefore, the scientists will not be looking at unrelated genes such as known cancer genes and those not associated with you or your family’s condition. To help interpret the code or gene better, parents may be asked to provide a DNA sample for WGS to compare with their child’s.
If this test is offered to you or your family, then your genetics doctor or genetic counsellor can speak to you in more detail about WGS or other genetic testing you may be eligible for.
What could a genetic test find?
A genetic test may find a change in a person’s genetic code which explains their MAC condition and symptoms.
The change may be found to have happened only in the DNA of the individual with the condition and not inherited or passed on from any parent. This is called a “de-novo” change and means “new” change. There is a low chance the same parents will have future children with the same condition, but your genetics doctor will be able to give you the most accurate information. If a de-novo change has been found there is some chance the person with the genetic change will pass this on to their children in the future. Please see the “How genes can be passed on” information sheet.
The genetic change may be found to have been passed on from one or both parents. Therefore, depending on the inheritance pattern (Please see the “How genes can be passed on” information sheet) there will be a chance future children may also have the same condition. Unfortunately, we do not choose which genes we pass on or do not pass on to our children, it is based on chance.
A genetic test may not find a change which explains the MACS condition.
Genetics is complex and we do not yet know everything about the genetics of MACS conditions. However, in the future new genetic testing may be available which is not yet available with the current knowledge and technology. Further research continues to be conducted into the genetic and environmental causes of MACS conditions, and our knowledge is growing all the time.
It may also be that the MACS condition has arisen due to non-genetic factors.
Your clinician will be able to discuss options of research and future genetic testing with you, where appropriate.
More on genetics
Head over back to the information on your genetic journey.