When DNA testing is performed as part of NBS or diagnostic testing, for example, CF or MCAD disease, infants can be identified as carriers of one abnormal allele, called a mutation. These infants are not expected to develop symptoms of the conditions. However, reproductive implications are present for their parents, siblings and other relatives, as well as the infant later in life. For some infants, genetic variants or biochemical abnormalities of unknown significance can also be identified. These infants may undergo additional testing to secure a diagnosis and are usually monitored over the long-term for the development of symptoms.